grow plants without soil

PLANT NUTRITION PROBLEMS CAN BE SOLVED BY THE APPLICATION OF SCIENCE

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Since perlite is devoid of available nutrients, the liquid feed applied to hydroponically grown plants is their only source of nutrition. This solution must therefore provide all the essential elements required for healthy growth and development. Moreover, each individual nutrient must be added at a rate which exactly matches its removal by the crop if deficiencies or toxicities are to be avoided. Thus, potassium may be added at a concentration of 400 mg/l, molybdenum at a mere 0.04 mg/l. Yet despite the 10,000-fold difference in concentration, molybdenum is just as important as potassium; without it there would be complete crop failure.

THE PERLITE CULTURE SYSTEM

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When used for commercial crop production, perlite is contained in 20 to 30 liter perforated bags designed to hold three tomato plants. A constant supply of aerated nutrient solution is maintained in the perlite by sitting the bags in a shallow reservoir of solution formed in the bottom of an outer polyethene gully by a series of polystyrene dams. Perlite's strong capillary attraction for water automatically draws up water from the reservoirs at the same rate as it is lost by evapotranspiration, irrespective of weather conditions or stage of crop growth.

THE IDEAL ROOTING MEDIUM

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Expanded perlite is physically stable and chemically inert. The porous nature of the cellular granules ensures a product that is light to handle, holds large quantities of readily available moisture and has a strong capillary attraction for water. Since it is free draining, it is also well aerated.

Its neutral pH, negligible nutrient content and a complete freedom from pests, pathogens and weed seeds combine to make this an ideal rooting medium for hydroponic culture.

WHAT IS PERLITE?

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Perlite is a volcanic glass formed when larva cools very rapidly trapping small quantities (2-5%) w/w) of water. When the glass is crushed and heated to about 10000C, the trapped water vaporizes and puffs out the softened granules to form white mineral foam.

GROWING HYDROPONIC CROPS USING PERLITE

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HYDROPONICS--- Hydroponic growing systems are based on a new generation of superb rooting media - inert, sterile, uniform materials such as the mineral perlite and rockwool. These products act merely as supports for a complete nutrient solution on which the plants depend entirely for their water, mineral nutrients and oxygen. In the purest form of hydroponics, there is a complete absence of solid substrate, the nutrient solution itself acting as the rooting medium.

Commercial growers can choose between three main hydroponic systems: one which uses a recirculating solution, the nutrient-film technique (NPT), and two 'static' systems, perlite culture and rockwool culture. The perlite culture system was uniquely devised and developed by a team of Scottish horticulturists. It is now the most widely used glasshouse crop production method in Scotland and it has the fastest growth of any hydroponic technique in the U.K. It is currently the subject of worldwide interest, particularly for use in arid zone regions.

FEEDING AND WATERING

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Potting Soils as a Medium

Gardening with potting soils provides beginning growers with a simple, straightforward way to try out hydroponic gardening. Plants grow in nursery pots and can be watered by hand, eliminating the need for pumps, timers, and water systems.
Potting soils may look like garden dirt, but they are "soilless mixes", made with peat, vermiculite and perlite. Because these materials are acidic, potting soils also contain a very fine powdered dolomite lime to balance the PH of the mix. Since nursery pots restrict air and water movement, potting soils are a "chunky" texture to keep roots healthy.

These soilless mixes contain no fertilizer - you use hydroponic foods (dissolved in water) to supply plants with all the nutrients they need.

Here are some guidelines for gardening with potting soils:
1) Use a good-quality potting mix
Some "mixes" are pure peat moss! Your hydroponic supply store can recommend a good potting mix. Many growers use commercial growers' potting soils since they are top-quality mixes. For small (one to two gallon) nursery pots, use "Sunshine #1" Mix; for larger (three gallon or bigger) containers, try "Sunshine #4" mix - it's very chunky and won't pack down too much in the bigger pots.

2) Use hydroponic nutrients designed for soilless mixes.
Potting mixes "soak up" some of the fertilizer so manufacturers have developed precise foods for this method of gardening. They are inexpensive, easy to prepare, and your plants will love them! A good "green growth" fertilizer is "Peat-Lite" mix (20-19-18). The numbers refer to the amount of nitrogen, phosphorous and potassium in the fertilizer. These are minerals used in large quantities by plants, called the macro-nutrients. "Peat-Lite" also contains several other minerals, giving young plants everything they need for fast green growth.
Another potting soil fertilizer, for flowering and crop production, is called "Blossom Booster" (10-30-20). Note that flowering plants and plants in crop production use less nitrogen - the first number-but more phosphorous and potassium. The important thing to realize is that there are precise easy-to-use foods available for plants in potting soils for each stage of growth.

3) Use the right size nursery pot
Very small plants can start in a 4" or 6" pot. Soon they will need to be transplanted to a one gallon nursery container later. This is how to check if plants need a larger pot: Slide pot away from potting soil to check roots. (The pot will slide off easier if the soil is not soaking wet). If the roots are showing on the outside of the soil, and they are starting to wind around between the soil and the pot, it's time to move plants to a larger nursery pot. Plants that are kept in pots too long develop long, winding roots - they are called "root bound" or "pot-bound" plants, and they often dry out very quickly. Even when pot-bound plants are transplanted to larger containers, their winding roots are slow to spread into the new potting soil. Transplanting crops before they're pot-bound helps the roots to spread quickly into the new soil. If you see any of these signs in your garden:
- Plants dry out quickly between watering.
- Soil shrinks away from container, leaving an air space between soil and nursery pot.
- The soil surface collapses, forming a bowl shaped depression on the top of the soil.
- Surface soil forms a hard "crust". Water can't flow through this crust: it just runs off the top of the soil and over the side of the nursery pot.
Then it's repotting time! Here's a general guide for repotting for fast- growing plants: 4" to 6" round or square pots - repot after 2-3 weeks into 1 gallon pots. 1 gallon pots - repot after about 4 weeks into 2 or 3 gallon pots.
Remember, this is only a general estimate - your plants might grow faster or slower, so sliding off the nursery pot to check root growth is always the best way. Remember to moisten the new soil before re-potting, and water the plant well when you've finished to settle it into its new container.

4) Feeding and watering
- Never fertilize dry plants - water well first and feed 1/2 hour later to avoid "burning" roots.
- Always use room temperature water. (21*C=70*F)
- Feed your plants today, then use plain water the next time they are dry.
- Water well to moisten the entire root system, then allow pots to drain excess water.
- Let plants dry a bit between watering, so they're not waterlogged.
- If plants are wilting, you waited too long!

Why you should alternate watering and feeding:
When you feed your plants, some of the fertilizer is "sucked up" by the potting mix. If you fertilized every time, the nutrients would build up in the potting soil and damage your plant's roots. When you give your plants plain water between feedings, it re-dissolves the fertilizer in the potting soil, making it available to the roots and helping to avoid fertilizer build-up. Using the "feed-water-feed-water" method keeps roots healthy and satisfied while the top growth gets all the minerals it needs. Other hints":

- Keep nursery pots off cold concrete floors - cold roots mean very slow growth!
- If soil packs down, loosen it gently with an old kitchen fork.
- Plants in the same pot for more than 6 weeks may benefit from an addition of very fine dolomite lime - use one tablespoon dolomite for a one gallon pot, two tablespoons for a two gallon pot and so on.

FEEDING AND WATERING

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Always use room temperature water

Never fertilize a dry plant - water it well and feed an hour later

In hot weather conditions - feed only every third time you water (90 degrees F or higher) and reduce Nitrogen feed by a third in hydroponic systems

Let water stand overnight or stir it to drive off excess chlorine

For plants in soil or sunshine mix:
- feed every other time you water during normal growing conditions
- add dolomite lime (one Tablespoon per gallon of soil) as a top-dressing to soil and work it into soil after 2 months of growth

For plants in hydroponics:
- watch PH and food strength. It really helps!
- flush with straight water in hot weather

GROWING IN SUNSHINE MIX OR PRO-MIX:

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(a) These soil-less mixes hold a lot of food.

(b) Feed every second time you water.

General Tips

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When setting up and maintaining your cloning box you must take care to provide your clones with the best propagating environment and care possible. To ensure fast rooting and high success rates, high humidity, 16 - 18 hours fluorescent light, proper air circulation, strict attention to cleanliness and correct bottom heat are absolutely necessary.

Humidity should be 80-85%. If air in cloning room is dry mist more often. Black leaf edges, black spots on leaves and mushy stems (damping off disease) are all indications of too much moisture and poor airflow. It is also essential that you provide adequate bottom heat. Do not try to skimp here. The cuttings and their cubes should be warm 24hrs per day. Often people fail to clone successfully because they do not provide bottom heat and clones will root poorly when nightime temperatures dip under twenty degrees centigrade.

Remember: Stress is bad. The faster your cuttings develop roots, the less stress they will undergoe. Any stress the cuttings are exposed to can result in a decrease of final yield by up to 50%. So treat your cuttings with a lot of T. L. C.

In emergencies: If you have to take cuttings from blooming plants, cut all the flowers off the cuttings. This will reduce stress. If planting clones outdoors treat with care and slowly acclimatise to the sunlight. Clean trays thoroughly between cycles. Use a weak bleach solution and water. Lots of bacteria and fungii spores can grow in dirty wet trays. This will lead to damping off disease. Remember cleanliness is very important. Do not resue growool cubes after they have been used throw them out and buy fresh ones they are inexpensive easy to store if kept dry. Do not clone from mother plants infested by spider mite. Keep your mother plant free of spider mites. Your cuttings will have little or no resistance to spider mites and will stress badly if attacked by the mites during cloning.

FLOWERING & CROP PRODUCTION PLANTS:

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Plants that are producing flowers or fruit or that are large enough to begin crop production:
(1) Flush the root zone by gently running room temperature water through the roots. Large plants could require up to a gallon of water. This clears the soil of any leftover fertilizer from the "green growth" stage.

(2) Use "Flower Food" formula for flower and crop production. First time feed at half strength.

3/4 teaspoon Calcium Nitrate "B" (5 grams) (use only 1/2 teaspoon/gallon in hot growing conditions) 1-3/4 teaspoon Flower Food "C" (12 grams) and stir well. Feed as required. Remember to flush the roots with plan water regularly.

For soil-less gardening in gravel, lava rock, rockwool and clay pellets

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BABIES:

New rooted cuttings or very young plants from seed.

Feed: 1/2 strength Flower formula
1/3 teaspoon Calcium nitrate "B" (2 grams)
Dissolve in one gallon warm water, then add:
1/2 teaspoon flower food "C" (3.5 grams) and stir well. Feed every second time you water your garden

YOUNG PLANTS:

Plants in rapid growth with established root systems.

Use a food especially designed to promote vigorous green growth. (First time - feed at 1/2 strength)

1 teaspoon Calcium Nitrate "B" (6.5 grams)
Dissolve in one gallon warm water, then add 1 teaspoon Hydroponic Food "A" (8 grams) and stir well.

Feed as required and flush the root zone with lukewarm water regularly, especially when garden temperatures reach 90 degrees F. (32 degrees Celsius)

Cloning - The Cloning Kit

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To begin successful cloning you will need the following items in your kit:

> Fluorescent fixture with two full spectrum fluorescent tubes per fixture.

> 280mm x 340mm Drip Tray, Seedling Tray and Plastic Grow Top.

> Growool Propagation Blocks - up to 3 fit a standard nursery seedling tray.

> Hormone rooting compound such as "Clonex", "Eziroot", or "Rootex-L".

> Heating pad or propagation mat.

> Superthrive - anti stress agent.

> Plant Root Zone Accelerant - hormone to enhance the development of roots.

> Reputable nutrient solution and a thermometer.

> Timer.

> New razor blade single edge and pruning shears or sharp scissors.

> Spray bottle for misting clones.

How To Take Cuttings

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Before you begin to take cuttings, it is a good idea to have all the equipment ready and in good working order. All equipment should be thoroughly cleaned and the cloning area should be as sterile as possible.

Step 1. Rinse the propagation blocks with a half strength nutrient solution to which has been added 4 drops of pH lower per two litres. Let propagation blocks soak for up to 10 hours prior to cloning in this solution. Discard soaking solution and just prior to cloning rinse blocks again with 4 litres of half strength warmed nutrient solution to which has been added 4 drops of Rootzone Accelerant and 5 drops of Superthrive. Insert thermometer into cubes and allow temperature to reach the green zone before cloning commences. Temperature should be maintained day and night within the range of 20 to 30 Cent if cloning is to be successful.

Step 2. Select cuttings - cuttings can be taken from anywhere on the mother plant provided the stem is of the correct thickness. Stem thickness should be between 4mm to 6mm diameter. Take cuttings with about four sets of well developed leaves and approx 100mm to 150mm in length. The topmost growing shoots make excellent cuttings however make sure the wood is of the correct thickness and not too green or to woody. You may wish to take a number of cuttings at one time immerse them in an ice cream container, or similar, filled with tepid water to which you have added a few drops of superthrive anti-stress formula.

Step 3. Take the single edged razor blade and begin trimming your cuttings. Take cuttings one at a time from tepid water and now trim bottom two sets of leaves flush with stem. Trim approx 50% of leaves by cutting across the leaf surface. It is hard for the cutting to keep these large leaves alive and they usually wilt and fall off if not cut in half. Cut the stem at fourty five degrees across the bottom leaf nodes. Gently scrape the cut area around the bottom of the stem. This disrupts the cells on the stem surface and helps them change into root cells. Take whatever rooting hormone you have purchased and dip the bottom of stem into your rooting compound. Here is a tip: Do not dip directly into rooting hormone bottle instead pour some off into a small container such as a thimble and discard what is not used. This saves you introducing any bacteria or disease into main container. Store main bottle of rooting hormone if refrigerator after opening.

Step 4. Now you are ready to put the cuttings into the growool propagation blocks. Gently insert the stem into the cube making sure the stem does not protrude out of the bottom of the cube. After all the clones have been prepared and placed in the propagation blocks you may water the block again with half strength nutrient solution to which you have added Superthrive and Root Zone Accelerant. Water the blocks until nutrient freely runs from the blocks allow to drain for a few minutes then place blocks inside the cloning chamber and place the chamber over the heating pad. You should close the vents on the grow top for the first 3 days. Check moisture and temperature for the first couple of days and mist cuttings morning and night with water to which you have added a couple of drops of Superthrive. Be careful to ensure that you do not have water sitting in bottom of tray. Growool cubes should be able to freely drain at all times. Place cloning chamber under flourescent fixture for approx 16 - 18 hours per day.

Step 5. After three days open the vent on the Grow Top. Monitor progress of clones for another 4 to 5 days by this stage it should be time to take Grow Top off the unit and expose clones to normal air - still continue misting morning and evening. Again monitor nutrient and moisture levels in the propagation block. By the end of a further 5 to 8 days you should be able to see root hairs protruding from the propagation blocks. Healthy roots look thick, white and hairy. Sickly roots look thin, yellowish or brown and hairless. The clones with the healthiest roots will be the same ones you will be proud of at harvest time.

Step 6. When your cuttings are well rooted and have begun to shoot it is time to transplant them into you growing system. Slowly introduce them to full strength nutrient and place them under a H.I.D. light system. Remember the new clones are tender and exposing them rapidly to a full strength H.I.D. lamp after the fluros would be a shock. Care should be taken to acclimatise your new clones to the brighter light. Start by raising the H.I.D. lamp approx one metre above the clones for the first few days slowly lower the lamp over the next week till the lamp is at the correct height. This will ensure a smooth stress free transition to growing under H.I.D. lamps.

CLONING Step by Step

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Cloning involves preparing a small cutting taken from a mother plant, treating the cut stem with a rooting hormone and placing the prepared stem cutting in a cloning chamber. The clone should grow roots and become an independent plantlet exhibiting identical characteristics to its' mother plant. Most soft or semi-hardwood cuttings will have developed roots within a week to ten days.

The name cloning simply stated means taking a cutting from a mature female plant in the vegetative stage and inducing it to grow roots. Clones will replicate the mother plant in every way ie: size, sex, colour, smell, taste etc. It is therefore crucial to have a mother plant of outstanding quality. The newly rooted cutting can be induced to flower immediately, or it can be put under a vegetative light cycle to attain a larger size.

As soon as the clone is large enough you can begin to take cuttings from it. Contrary to rumour, this can be done infinitely without any loss of desired qualities.

The Mother Plant

It is important to choose a mother plant carefully. When selecting a suitable mother plant consider the following:

> Aesthetic qualities, shape, density of leaves, compactness and size.

> Heavy flowering/fruit production.

> Disease and insect resistance.

> Early Maturation

> Clones well and produces strong new plantlets.

It is important to remember that your mother plant should be healthy and stress free. Cuttings coming from a stressed mother plant may root poorly, be slow growing, produce poorly and become mutated. It is important to reinforce that the condition of your mother plant is paramount to the success of your clones. Vigorous genetic stock can be lost by cloning from poorly cared for mother plants. As a general guide do not take more than 20 - 30 % of the vegetative material from each mother plant and do not take cuttings from the mother plant more than three times.

Each time you take cuttings it is a good idea to start a new mother plant from the most vigorous clones. Remember if growing initially from seed to select only the best genetic plants to use as mothers for cloning. Seeds will never produce the same consistent results you can expect from clones.

Light

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For propagation purposes, fluorescent light is ideal operated for between 16 - 18 hour per day. The light should be operated on using an electronic timeswitch to ensure that the ON time and OFF time are the same each day. As fluorescent lights are of a low intensity they should be positioned as close to the plants as possible.

Temperature & Humidity

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Maintaining constant temperature of between 20º - 28ºC encourages rapid germination and healthy seedlings. It is important to note that the faster clones or seedlings establish, the higher the success rate and the healthier the young plants will be. Temperature and humidity play an important role in successful propagation. Clones or seeds should be placed in a cloning chamber to promote a warm, moist environment. While humidity is important, monitor the chamber daily to avoid excessive condensation build up. As a rule, if water droplets trickle down the sides of the chamber, it is too wet and the vents should be opened, as extremes of temperature and/or excessive humidity will inhibit germination and the establishment of healthy seedlings.

pH

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pH is important not just for established plants but also when propagating. Always maintain pH levels between 6.2 - 6.8 pH. pH levels should be tested and adjusted if necessary before sowing seeds and at least weekly throughout the growth of the plant. Incorrect pH levels can cause toxicities of some nutrient elements and cause other nutrient elements to be unavailable to the plants therefore adversely affecting plant growth.

Watering

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Seedlings and clones need only a light mist spray to keep media moist and raise humidity, and provide food for the young plant. When misting, it is best to use a warmed 1/2 strength nutrient & Superthrive to avoid burning the tender young shoots.

VENTILATION

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VENTILATION an average 10' x 10' foot vegetable garden will use from 10 to 30 gallons of water per week. Where does all this water go? It transpires and evaporates into the air. So basically, gallons of water will be held in the air. If this moisture is left in a small room, the leaves will get limp, transpiration will slow (remember the flow of water through the plant helps keep it erect) and the stomata will be stifled. This moisture mist be replaced with dry air that lets the stomata function properly. A vent fan that pulls air out of the grow room will do the job.

To be a Successful indoor gardener.

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Successful indoor gardeners know that a vent fan is as important as water, light, heat, and fertilizer. In some instances it is more important. All greenhouses have large ventilation fans. It is sometimes said that the person with the most fans wins.

Vent fans are rated by the number of cubic feet of air per minute (cfm) they can replace or move. Buy a fan that will replace the volume (cubic feet) of the grow room air in about 5 minutes or less. The air that is pulled out is immediately replaced by fresh air which is drawn from little cracks under the doors or window sills. If a grow room is sealed tightly then an intake fan will probably be necessary to bring in fresh air.

A vent fan is able to pull air out of a room many times more efficiently that a fan is able to push it out.

To calculate the room size multiply width by height this will give you the total cubic footage of your room for example 10 by 10 by 8 = 800 cubic feet. Remember that you want your fan to exchange the air within 5 minutes so for a room that is 800 cubic feet a fan that is capable of moving 160 cfm is needed.

CIRCULATION

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CIRCULATION if the air is completely still, plants will tend to use all of the C02 next to the leaf surface. When this air is used and no fresh air is forced into its place, dead air space forms stifling the stomata, slowing growth. Air also stratifies with the warm air rising and the cooler air settling towards the bottom of the room.. All of these potential problems are avoided by opening a door or window and installing oscillating fans. Air circulation is important for insect and fungus prevention. Mold spores are present in all growrooms.

What is STOMATA?

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STOMATA are microscopic pores which are located on the undersides of the leaves. These stomata regulate the flow of gasses into and from the plant. These can get clogged with dust, filmy residues, pollen etc... So it is very important to have air movement to keep these pores clean and free.

Air Circulation

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Fresh air is at the heart of all successful indoor gardens. In the great outdoors, air is abundant and almost always fresh. The level of C02 in the air over a field of rapidly growing vegetation could be only a third of normal on a very still day. Soon the wind blows in fresh air. Rain cleanses the air from dust and pollutants. The ecosystem is always moving. When plants are grown indoors the natural balance that is present out of doors must be achieved indoors by way of fresh air ventilation. You must take the task of bringing in fresh air seriously or else your green thumb is going to wilt and turn brown.
Fresh air is inexpensive and easy to find. An exhaust fan is the main tool used to satisfy this need.

In order to have a good flow of air through your growing environment, adequate air circulation and ventilation are necessary. Indoors, fresh air is one of the most commonly overlooked factors in contributing to a plentiful harvest. Experienced gardeners realize the importance of fresh air and take care in setting up proper air movement. Three factors affect air movement: stomata, ventilation, and circulation.

The Easiest Way of All

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The easiest way of all, is great for people who just want to get rid of the heat and are lucky enough to live on a lake, stream or the ocean. All that is required is to string several hundred feet of garden hose from the pump in the reservoir, out into the lake and then back to the house where it is connected to the inlet to the lights. You then just pump the light cooling water from the reservoir, through the hose in the lake where it gives off its heat before re-entering the lights. No expense for cooling water, no fancy plumbing, no heat exchangers - just the lights, a pump, a filter, a small reservoir and some hose.

Lights as a Pool Heater

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Another option is to waste the heat from the lights to a swimming pool. For people who don't have an in-ground pool installed in their back yard, a coated steel above-ground pool is a great alternative. They are cheap, easy to install, and enjoyable. You not only can get rid of the heat from your greenhouse or solarium, but you also get a heated pool.

Extra-low Water Consumption System

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An interesting variation on a re-circulating system is one which allows use of city water without increasing facilities water consumption by much. It does this by tying the heat exchanger into the domestic water supply in such a location that whenever any water is used for any domestic purposes the light cooling system is also cooled. Depending on where one puts the reservoir it can also provide heating for a solarium or greenhouse too. While it does require a fair sized reservoir, a considerable number of lights can be cooled with very little extra water, which is a great advantage for the areas where water is metered.

Re-circulating System

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For those with a bit more concern for the environment or who want to keep water costs down, there are a number of cooling options which can cut down on the consumption of water and/or electricity. One of these is simply to use a re-circulating system which will allow you to use other sources of water and is in fact the system recommended by the manufacturers of the water cooled lights. The heat exchanger keeps the water flowing through the lights completely separate from whatever the cooling supply is, so the cold water can be from any source. Common examples are sea water, streams, lakes, wells or even swimming pools.

Water Cooled Lights

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Since water cooled growing lights have been in use by the hydroponics industry for a number of years now, it seems like a good time to look at them more closely and the best place to start is by showing just how leading edge a development they are - probably much more so than most people imagine. Why do I say that? It is because I have in front of me, a scientific research paper from NASA, the people that send out the space missions. The author is a researcher at the NASA Ames Research Center, and the research was conducted in early 1996 at an Antarctic research station.
The project purpose was to develop a mini-farm sufficiently productive to supply food for a manned mission to Mars. It had to be energy efficient, small, light weight, and most importantly, highly productive - all desirable attributes for the home grower as well. The research was done using a high productivity growth chamber (CAAP chamber) fitted with lighting which featured " ....a recirculating water jacket that absorbs and removes non-photosynthetic energy". In plain English, they used water cooled lights - the same type of water cooled lights that have been available to home hydroponic growers for several years already.

To quote the report:

"The high-efficiency lighting system, providing unmatched photosynthetic radiation production and delivery efficiencies.........."

"The area required to produce the necessary human diet is much less in the CAAP"

"Yield expressed on an area, volume and integrated resource input basis are all greater for CAAP"

"Performance of the lighting system has been excellent........."

"The performance per unit area is so much greater in CAAP......."

Their conclusion at the end of the project was that even the results they got from this preliminary study met the minimum requirements for a mini-farm in space, something they had not been able to achieve with standard hydroponic practices and lighting,, and they saw many areas which they could still improve.

While growth chambers have been used for decades, the report stresses that it was through use of the water cooled lights that the performance has been optimized to the point that it may be feasible to grow the food in space. One has to think that if research scientists and engineers at NASA conclude that water cooled grow lighting has proven itself in their application, it is probably worth looking at for use in other applications.

Can home hydroponic growers benefit from these lights as well as NASA? Yes, because using a growth chamber doesn't require rocket scientists - there are several manufacturers of perfectly suitable growth chambers in Canada, the US, etc. How do the results obtained from these chambers compare to those of NASA? With billions of dollars to play with, NASA can spend a lot on fancy equipment and will probably do better than a home gardener, but still, the home gardeners have done very well and they got there long before NASA.

The growth chambers already available to the home grower have been shown by numerous growers to provide increases of about 30% - 50% beyond what was produced from standard hydroponic systems with everything else being the same - the same person doing the growing, the same strain of plants being grown, the same nutrients being used, etc. If the only thing they changed to obtain the increased production was to use a water cooled light equipped growth chamber, it suggests that using a similar growth chamber could provide anyone with a similar increase in productivity. What does a growth chamber consist of ? At its simplest, it's a box fitted out with everything needed for growing. It would have the light, fan, controls, ballast, watering and any other necessary equipment, already assembled.

One great advantage of these units is the ease of use. There is no trial and error period, or any of the trouble of installing a system assembled from parts. The growth chambers are already proven products with all the components provided, all sized properly and all assembled correctly. They can sometimes be purchased as kits for self assembly but generally they are sold in the completely assembled form so they are true plug and grow units - plug them into the power and water supplies and start growing.

And what are the advantages? Why should anyone bother with water cooled lights in a growth chamber if they've always grown OK without them before? There are many answers, but to quickly summarize:

1.Greater productivity at all times in a properly built growth chamber
2.Easier control of disease and insect pests
3.Increased efficiency of CO2 enhanced operations
4.Reduced size of the installation
5.Reduced ventilation needs and no noise, odor or light glare into the
surroundings
6.Better isolation of the growing environment from it's surroundings
7.Enables year round operation during any weather conditions.
8.Ability to use a modular, plug and grow approach for rapid, easy setup
and expansion.
9.Fast and easy teardown and removal when needed

Since use of the water cooled lights is what makes the growth chambers practical, some discussion of the lights themselves is called for. The hydroponic industry has had water cooled lights available to it for a number of years already and like any other new innovation they've had their teething pains. The initial offerings from several different manufacturers were either huge, heavy and difficult to handle, leaked constantly, were difficult to take apart for cleaning, prone to cracking and meltdown, or just too expensive but these problems all seem to have been overcome finally. The latest version on the market exhibits good design, ease of use, and finally a reasonable price for a complete package of parts - including a reflector.

The lights use standard HPS and Metal Halide lamps, which are fitted into a water jacket that removes the heat while still allowing all the visible light to reach the plants. This warm water can either be run to waste if there is no wish to use the heat in another application, or the heat can be recovered for use elsewhere. The number of cooling options is considerable.

Minor Elements

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Manganese (Mn) – plays an important role in photosynthesis and chloroplast membrane formation. Needed at only ½ the rate of iron, its importance cannot be understated. Manganese also enters into the chemical reactions of oxidation and reduction. Deficiency – dead (necrotic) spots on younger leaves. Hard and woody stems, slow maturity. It is not very mobile in plants, so younger growth usually exhibits symptoms first. Toxicity – wilting and death in all but small quantities. Note: manganese is toxic in large amounts.

Boron (B) – is needed in small amounts. Boron aids in cell division and in transporting sugars through cell walls. It also aids in forming the amino acids – thymine and cytosine, important to DNA synthesis. Deficiency – affects new growth first. Black, brittle areas on leaf tips. Small, burned leaves with dead spots. Stubby brown and dead root tips. "Heart rot" in beets and "stem crack" in celery. Toxicity – above 10 PPM, dead leaf margins, wilting and quick death of the plant.

Copper (Cu) – is needed in only small amounts. This metal aids in plant metabolism and general health. It helps ward off disease and pests, aids in the utilization of iron and the manufacture of enzymes. Deficiency – dark green, spindly young leaves. Plants are susceptible to disease and insects, wilt easily and exhibit stunted growth. Toxicity – dark roots, leads to an iron deficiency (interveinal chlorosis on young leaves).

Zinc (Zn) – is needed in small amounts for growth and chlorophyll synthesis. Deficiency – short stem internodes and a condition called "little leaf" or "rosetting" where the young leaves are spindly and twist around each other. Reduced or no bud formation. Mottled dead spots between veins. Toxicity – related to an acid pH, splotchy mottled leaves and wilting.

Chlorine (Cl) – this element controls water uptake and transpiration. Stimulates photosynthesis and is a major constituent of the anthocyanin molecule. Deficiency – plants wilt easily. Bronze colored leaves with dead or chlorotic spots, stunted roots with club-shaped tips. Toxicity – saline poisoning, small dark leaves, burned margins and wilting.

Molybdenum (Mo) – a catalyst needed in small quantities. It is involved in nitrogen fixation (assimilation) and in the manufacture of enzymes. Deficiency – causes nitrogen deficiency. Plants are light green, malformed and stunted. Causes the "whiptail" disease where young leaves are long, narrow and severely twisted, but not tightly bunched as in "rosetting" caused by zinc deficiency. Toxicity – very toxic to plants above 100 to 200 parts per billion (not much!). Causes iron and copper lockup and improper nitrogen utilization.

Cobalt (Co) – a constituent of vitamin B-12 and required for the fixation of nitrogen and DNA synthesis. Deficiency – causes pernicious anemia (lack of vitamin B-12) and improper nitrogen assimilation. Toxicity – all but the smallest amount causes quick wilt and death.

What is the NPK and how is relevant to a hydroponic nutrient? The NPK is the ratio of the levels of nitrogen, phosphorus and potassium. Note that the NPK is important in choosing the right nutrient for the proper stage of growth exhibited by your plants.

The nutrient solution in hydroponics, like the in-the-soil solution for traditional soil gardeners, provides the plant roots with water and essential elements. In hydroponics, the essential elements are added to the nutrient solution, using fertilizer (mineral) salts.

There are a number of hydroponic nutrients on the market these days but they mostly fall into one of four categories – they can be either liquids or powders, and these can be either a one or two part formulas. Most hydroponic retail centers offer a wide range of powder and liquid, one and two part, grow and bloom nutrients.

Powder nutrients are more concentrated than liquids and are usually less expensive. Powders should be dissolved in hot water to make a liquid concentrate, and not be used by adding the powder directly to the tank. This should be done to insure that the powder dissolves completely. If a liquid concentrate is to be made from a two-part powder formula, it is essential that the final volume of the two solutions be the same.

Liquid nutrients are more popular with most hydroponic gardeners because they are easier to use. Liquid nutrients can be added directly to the tank, while powders should be mixed separately then added to the tank. Also another thing to remember is that liquids should be shaken well before dilution, to get an even mix of nutrient chemicals by getting the sludge moving.

The strength of a nutrient solution is measured by its electrical conductivity (EC) and is of critical importance. Too high an EC results in vegetative growth at the expense of fruit or flower production and too low an EC produces weak, unproductive plants.

The EC can be expressed as TDS (total dissolved salts) or ppm (parts per million) depending upon the meter that is used. TDS is the concentration of s solution as the total weight of dissolved solids. These meters are widely used by hobbyists, and actually measure the electrical conductivity of a solution. They do this by measuring the amount of electric current a solution carries. The meters use a built-in conversion factor to express the electrical conductivity in TDS/ppm. The conversion factor for true TDS/ppm is expressed as:

True TDS/ppm = 640 x EC (mS/cm)

For example:

EC (mS/cm) x 640 = 640 True TDS/ppm

Toxicity – edges curl on leaves, small stems, signs of potassium deficiency.

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Sulfur (S) – is a building block of amino acids and proteins. Used in small amounts, it aids transpiration and transport of other elements. Deficiency – rare, but young leaves turn pale green with yellowing along the veins, stems turn hard and woody. Plants are stunted and spindly. Toxicity – saline condition, wilting.

Iron (Fe) – is an important constituent of enzymes and plays a role in photosynthesis. Iron is not very mobile in plants and can be "locked up" if the pH goes much above 7. Deficiency – yellow or white chlorosis between veins of younger leaves. Stunted new growth with spindly stems. Flowers drop off before opening. Toxicity – deficiencies of other elements, brown spots on leaves.

Major Elements

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Nitrogen (N) – a major element needed by all green plants. It is transported from older growth to new growth. Deficiency – lack of lush green color, especially in older leaves. Toxicity – soft, dark green leaves, long weak stems, poor root development and slow to maturation.

Phosphorus (P) – an important mineral that stores energy in plants and animals, also a flowering agent. Deficiency – stunted, dark green leaves. Lower leaves turn yellow and die. Leaves have brown or purple spots. Toxicity – small, curled new leaves. Early maturity, large root systems.

Potassium (K) – a nitrogen catalyst needed for enzyme manufacture. Needed in large quantities, although plants do not use a tremendous amount. Deficiency – brown, necrotic (dead) tips and edge margins on older (lower) leaves followed by yellowing of the entire leaf. Dead brown spots on older leaves. Slender, weak stems and small seeds. Toxicity – saline condition, marginal leaf burn, wilting and drying due to poor water uptake.

Calcium (Ca) – helps form the structural parts of the plants (it is a major element in cell walls). Counters acidity (low pH). Deficiency – new growth affected first. Root tips turn brown and die. Hard, stiff new leaves with dead edges and brown spots. Stems are stunted and woody, blossoms fall off. Little or no fruit. Toxicity – rare, but can cause an alkaline (high pH) condition, wilting, iron and potassium lockup and deficiencies. Calcium is not very mobile in plants.

Magnesium (Mg) – is important in photosynthesis and the chlorophyll molecule where light energy is converted to chemical energy. Chlorophyll gives plants their green color. Deficiency – chlorosis (yellowing) of older leaves between the veins. Later, leaf tips curl, entire plant turns yellow and dies. Magnesium is mobile and is transported from older to newer growth. Old growth is affected first.

Nutrients are an essential part of healthy plant growth.

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For a plant to grow, it requires the correct temperature and humidity, moisture, light, air, certain mineral salts (nutrients) and the absence of pathogens (disease causing organisms).

Plant nutrition is the science which studies what plants eat, or more to the point which nutrients the plant takes from its surroundings, in what amounts, under what conditions and how what the plant takes is used in growth and development. This is of great importance to anyone who is interested in maximizing the genetic potential of his/her plants.

A hydroponic nutrient solution is composed of water, dissolved air and a dozen or so essential elements in their proper proportions. The essential elements, or mineral elements that must be present for proper plant growth and development are nitrogen (N), phosphorus (P), potassium (K), magnesium (Mg), calcium (Ca), sulfur (S), iron (Fe), manganese (Mn), boron (B), copper Cu), zinc (Zn), molybdenum (Mo), and chlorine (Cl). The letters in parentheses are the chemical symbols for each element. In addition to these elements, hydrogen (H), oxygen (O2) and carbon (C) are also essential elements which can be found in the air and the water.

The elements that make up a nutrient solution are broken up into two different categories depending upon their relativity to the total make-up of the nutrient solution. Hydrogen, oxygen, carbon, nitrogen, phosphorus, potassium, magnesium, calcium and sulfur are required in relatively large amounts and are so called macroelements (major elements), while iron, manganese, boron, copper, zinc, molybdenum and chlorine are required in relatively small amounts and are so called microelements (minor elements).

Hydroponic nutrients should be complete, containing every essential element, both major and minor, required by all green plants for optimum plant growth. The nutrient should be well balanced containing enough of all essential elements so no deficiency occurs, while not containing too much of any element that might lead to a toxicity. Also the nutrient should be pH balanced and buffered preventing the pH from drifting too high (alkaline) or too low (acid). The last and maybe most important requirement is that the nutrient solution be water soluble with minimal or no residue. The mineral salts used should readily dissociate into elemental ions and not contain any toxic chemicals or elements like heavy metals (lead, mercury or tungsten). This is controlled by the selection and purity of the raw ingredients used.

Drip Irrigation Technique (DIT)

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Drip Irrigation Technique (DIT) Grown in inert or organic material and the nutrient solution are fed around the root system 6-7 times a day, in drops or trickles. This technique is called as Drip Fertigation Technique.

Root Mist Technique (RMT)

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Root Mist Technique (RMT) A nutrient mist solution is sprayed every 4-5 minutes onto the roots of the plants that hang from frame in a root chamber. This technique is known as Aeroponics. This technique is good for starting roots, cuttings and also for extracting (milking) in the pharmaceutical industry.

Nutrient Film Technique (NFT)

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Nutrient Film Technique (NFT) This technique helps the root system with a thin film of nutrient solution which is always in contact with the roots while the nutrient solutions circulates and the root surface is exposed to air.

Aerated Flow Technique (AFT)

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Aerated Flow Technique (AFT) A modified version of DFT, the nutrient solution is amply aerated by special mechanisms. The Japanese Kyowa Hyponica Technique is somewhat similar to AFT.

Fog Feed Technique (FFT)

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Fog Feed Technique (FFT) This technique is similar to RMT but the nutrient solution droplet size is very minute. This technique is good for plants having aerial roots. Example: orchids, anthuriums, etc.

Deep Flow Technique (DFT)

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Deep Flow Technique (DFT) The depth of nutrient solution (4-6 cm) is circulated around the roots either by gravity or by using a pump. This technique is also referred to as Dynamic Root Floatation Technique and as Raceways Hydroponics.

Ebb and Flow Technique (EFT)

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Ebb and Flow Technique (EFT) Flood & Drain Technique EFT is the same as Static Aerated Technique SAT, but the nutrient solution in drained off 3-4 times a day to permit the roots to breathe.

Static Aerated Technique (SAT)

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Static Aerated Technique (SAT) Also referred to as a Passive Technique. Plants are grown in a depth of static nutrient solution, which is aerated by providing air space in the root zone or by pumping air into the nutrient solution in the tank. This is a basic method of hydroponics.

Dissolved Solids in Water (TDS)

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Bad water can cause big problems. Pure water is often not available to hydroponic growers. Almost all domestic water supplies contain certain "dissolved solids," minerals that cannot be filtered out in the way that particles can. Generally these conditions won't cause too much trouble. A simple pH adjustment will usually correct an imbalance caused by "hard" water.

However, there is a limit. In some areas the amount of total dissolved solids or of specific elements in the water supply can combine with elements in the nutrient solution resulting in nutrient lock-out. This may occur when well water is used to mix nutrient solution or where the municipal water supply is very hard. Water containing more than 50 parts per million (ppm) of calcium and magnesium (called "total hard- ness") can create serious problems. Other common elements that may be present in hard water include various carbonates, sulfur, sodium, iron and boron.

Your municipal water supplier can provide you with an analysis of your water supply. If you are using well water, there are many laboratories that can provide you with an analysis if you send them a sample. If the news is bad, it may be necessary to collect rainwater (a good idea wherever possible), install a reverse osmosis filtration system, deionization system, steam distillation system or use purified water (not mineral or "spring" water).

Dissolved solids (ppm) can be measured by using an instrument called a conductivity meter. Pure water will not conduct electricity. The higher the amount of dissolved solids the solution contains, the higher its conductivity will be. Thus, the conductivity meter can measure the electrical conductivity in the solution and interpret that measurement as ppm. Generally this method is the best available to the home grower to measure water quality before nutrients are added and to identify dissolved solids (ppm) after adding the nutrient mix.

It is critical that the nutrient solution not exceed the plant's tolerance for dissolved salts. That tolerance can range from extremely low for some plants such as orchids, to a very high for salt-tolerant crops such as barley. Unless you know the specific tolerance of a given crop, it is best to use a nutrient between 800 and 1,200 ppm.

When in doubt, remember that it is always better to apply too little nutrient than too much. The typical "dose response" curve of plants to variations in nutrient concentration shows three distinct and sharply defined zones: a "deficient zone" where there are insufficient nutrients for healthy plant growth; a "tolerant zone" in which sufficient nutrients are available; and a "toxic zone" where nutrient concentration is too high (too strong) for healthy plant growth.

A complicating factor in determining nutrient strength is that not all salts give equal electrical conductivity readings at specific concentrations. For example, monopotassium phosphate, a common salt used in the composition of plant nutrients, offers very poor conductivity and is practically invisible to conductivity meters. Nutrient solutions containing high monopotassium phosphate levels will appear to be much weaker than they actually are. It is important to be aware that this type of nutrient is stronger than it appears to be, based on your readings.

Always follow the manufacturer's recommendations for mixing nutrient, then measure the conductivity of the resulting solution. This will tell you what "indicated ppm" should be for that particular nutrient solution when mixed with your water supply, although "actual ppm" is probably higher.

As plants consume nutrients and water, the nutrient strength will change in the hydroponic reservoir. In hot, dry regions it is common for plants to transpire lots of water; if you measure the ppm you may find that it rises. It will be necessary to top off the reservoir with water and bring the indicated ppm down to a reasonable level. In cool, humid environments you may find that the ppm drops; this is because the plants are consuming nutrients and not transpiring lots of water. It will be necessary to top up the reservoir with nutrient solution in order to bring the indicated ppm up to its proper level.

A fast growing crop can consume huge amounts of nutrients. If you have a small reservoir it is important to change the solution frequently. Depletion of the solution will result in slow, spindly growth and sickly plants. A large reservoir in proportion to the total bio-mass will not have to be changed as often. Small plants, or naturally light feeders will deplete nutrients more slowly. Different types of plants have differing nutrient needs. The composition of nutrient solutions for all types of plants will contain the same elements as the list at the beginning of this article, however, the ratio of these elements can differ greatly. These variables can be striking when the nutrient needs of one type of plant are compared with the needs of another.

For example, orchids prefer a nutrient that is not only mild (low ppm) but also of a different NPK ratio in comparison to a high metabolism plant such as a fruit producing annual which must complete its entire life cycle within one growing season - from seed germination, through seedling, vegetative growth, flowering, fruit and seed production. Moreover, the fruiting annual which is going through this high-speed metamorphosis in less than one year will also have greatly differing nutrient needs during the various stages of its life cycle.

During rapid vegetative growth a plant can use lots of nitrogen, but a flowering or fruiting plant needs more phosphorus and magnesium. Hydroponic cultivation enables the grower to provide different diets for the crop at different times during the growth cycle. One of the great advantages of hydroponic over soil cultivation is the ability to manipulate nutrient concentrations for enhanced plant growth.

There are manmade nutrient formulations on the market that provide the same NPK combination throughout the plant's life cycle. The best of these are crop-specific formulations. Many manufacturers produce a particular product for orchids, another for tomatoes and perhaps another for indoor ornamentals.

These products will provide reasonable nutrition for the particular crop for which they are designed. However, since it is not possible to alter the NPK combinations during the various phases of growth, it is not possible to perform "nutrient manipulation" with general-purpose products. A multi-stage nutrient that permits adjustment of total ppm and NPK ratios will help you gain the full advantage from your hydroponic system.

What is pH all about?

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Maintenance of the proper pH in the irrigation stream helps prevent chemical reaction of fertilizers in the irrigation lines. High solution pH can cause line clogging precipitates to form. Correct pH level ensures that phosphates remain in the more soluble hydrogen form and that minor elements are more available for plant uptake. Minor element deficiencies can result from high pH. What is pH? The abbreviation pH stands for "Potential Hydrogen" and refers to the concentration of positively charged hydrogen ions (H+) relative to negatively charged hydroxyl ions (OH-), in a substance. Hydrogen ions are acidic in nature while hydroxyl ions are basic or alkaline in nature. The pH scale, which measures the concentration of hydrogen ions runs from zero to 14 with 7 being neutral (equal number of H+ and OH- ions). Any value below 7.0 indicates acidity and any value above 7.0 indicates basic or alkaline conditions.

An acid such as Nitric Acid (HNO3) or phosphoric acid is a substance which, when added to water, breaks apart or "ionizes" to provide hydrogen (H+) ions. A base ionizes to provide hydroxyl ions (OH-). The terms strong and weak applied to acids indicate the degree of ionization they undergo. A strong acid such as hydrochloric in a dilute solution undergoes 100% ionization whereas a weak acid like acetic exhibits only 4% ionization. In North America most water supplies are alkaline. In addition plants tend to make the root environment more basic. When a plant takes up nitrate ions, which are negatively charged, the roots shed negatively charged hydroxyl ions to maintain electrical balance. This raises the pH of the root environment. When positively charge ammoniumions are taken up, positively charged hydrogen ions are shed, acidifying the root environment.

When deciding on a pH correction program, the pH of the water is not the only thing to consider, Buffering capacity (the ability of the water to resist pH change) has to be taken into account. The buffering capacity of water is related to the amount of bicarbonate (usually calcium bicarbonate) that is present. If there is a lot of bicarbonate present, much more acid is needed because of the reaction that takes place between the bicarbonate and the acid. The acid that Is added initially to water containing bicarbonate is Used up in this reaction. The hydrogen ion from the calcium bicarbonate molecule (above) and the hydrogen ion from the nitric acid molecule (above) combine to form water. This means that the hydrogen ion from the acid is locked up and therefore does not lower the pH. Once sufficient acid has reacted with the bicarbonate present, any additional acid added will contribute hydrogen ions to lower the pH; therefore, the more bicarbonate that is present, the more acid wit) be needed before free hydrogen ions are available to lower the pH.

Many fertilizer components are acidic and lower the pH, while others are alkaline and raise the pH. To achieve the proper pH with fertilizer alone, however, would require water with little to no bicarbonate present, When nitric acid ionizes, it provides nitrogen ions as well as hydrogen ions; phosphoric acid provides phosphorous. Which acid should you use? Consider the following: Plants use more nitrogen than phosphorous. In addition, high phosphorous levels can cause the formation of calcium and magnesium phosphate; a hard, scale-like precipitate than can coat, and eventually plug, feed lines. It may, according to speculation, even coat plant roots, blocking air passages. Further, high phosphorous levels can hinder the uptake of some minor elements, We believe phosphoric acid should be used only if the amount of acid required is constant and the level of phosphorous provided by the phosphoric acid will not create excessive phosphorous levels in the solution. If you are using a "proprietary" blended fertilizer such as 20-20-20, phosphoric acid should likely not be used at all, as the levels of phosphorous in the blend are usually at an optimum level.

It seems nitric acid is the better choice in many instances. Bear in mind that nitric acid is more dangerous to use. Nitric acid is highly corrosive and produces poisonous fumes when exposed to the atmosphere in the concentrated form. A spray mask, eye protection and rubber gloves should be worn when handling it. Nitric acid is much less hazardous once diluted. Concentrated nitric acid should be stored in sealed glass or stainless steal containers.

Potential Hydrogen can be important for more than fertilization and irrigation. It also plays in the use of some pesticides. Alkaline water can break up the molecules of certain pesticides in a process called alkaline hydrolysis, reducing the activity of the chemical. This problem is heightened if the tank mix will be sitting for any length of time prior to application and if ambient temperatures are high. There are other greenhouse compounds rendered more effective if the water added to is pH corrected before hand.

Finally, at the end of a crop, low pH can be used to clean irrigation lines and dripper tubes of any scale that might have formed. This is done by charging the lines with a low pH solution (3-4) and letting it steep overnight. The lines should then be flushed thoroughly before being put back into regular use.

Hanging basket tomatoes

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Here are some tomatoes (variety Tumbling Tom) grown by Kath in Linlithgow, near Edinburgh. They are planted into some of our Self-watering Hanging Baskets and fed our Tomato Liquid Feed. This is a great idea if you don’t have much space and miss the just-picked flavour of home-grown tomatoes.

Kath says:"I really was amazed at how easy it all was to do and I'm sure the tomatoes taste better than our greenhouse soil-based ones. Will be trying it again next year."

Grower’s Diary

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It was about this time of year, last year, that my pond bound fish prayed daily for a giant iceberg to make its way up from the Southern Ocean. The temperature in my greenhouse reached an all-time high of 119 degree’s F. The tomato plants thought it was Christmas Day each and every day. This year the plants, especially the one’s grown from seed, are having a bit of an up hill struggle. Each day the weather man promises them sunshine, most days he is getting it wrong. Being an honest Leo I must confess to my own contribution to their misfortune. It was only yesterday that I realised I was giving them the wrong nutrient mix – ‘A’ and ‘B’ only. I should have added liquid feed ‘C’ at the third leaf stage, which was a month ago ! This, of course, applies only to those tomato plants which have been brought on from seed.

The other Tommy plants, which were purchased as established young plants, are doing remarkably well and are about two feet tall ( the seeded plants are little more than three to four inches high ) and well into their flowering stage. You may recall that I have attempted an experiment with three tomato plants of the same variety, Beefsteak, in pyramid pots. One is sitting in coconut fibre, one in vermiculite/perlite, and the third is in a sharp/soft sand mix, all being fed the same liquid feed. The plants in the coconut fibre and vermiculite/perlite pots are racing away as if their backsides are on fire, and are beginning to bully neighbouring tomato plants for space. The tomato plant set in sand is a sad tomato plant, and I think it only a question of time before it becomes a deceased ( as in dead ) tomato plant. But I am prepared to accept full responsibility for it’s eventual demise, and I promise to do better next time.

Which brings me to the peppers. The Capsum peppers ( grown from seed ) are not doing too well either, yet ( and understandably so, no doubt ) the Yellow Luteurs, bought as established plants, continue to reach upwards to glory. The Beetroot, Carrots, Spring Onions and Radishes ( all grown from seed ) are now ready for a little thinning – especially the Radishes. Still in the propagating stage are Leek, Parsnips and two types of Lettuce. The Mixed Salad lettuce have produced a nice green carpet over the propagating tray, but the Salad Bowl lettuce ( with the exception of just two little plants ) refuse to come out and join in the fun. Not all the Leek seeds are making a show, hopefully time will produce better results. The Parsnips are looking good, and I have built a Parsnip growing tray, with the use of drain-piping, and await the young seedlings to reach a better maturity so they can be transplanted into their individual drain-pipes.

Now there’s a thought that might boggle the mind – if you want to grow a parsnip, get a drain-pipe.

Augmentation

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Augmentation involves releasing natural enemies into areas where they are absent or exist at densities too low to provide effective levels of biological control. The beneficial insects or mites used in such releases are usually purchased from a commercial insectary (insect rearing facility) and shipped in an inactive stage (eggs, pupae, or chilled adults) ready for placement into the habitat of the target pest. Augmentation is broadly divided into two categories, inoculative releases and inundative releases.

Inoculative releases involve relatively low numbers of natural enemies, and are intended to inoculate or an area with beneficial insects that will reproduce. As the natural enemies increase in number, they suppress pest populations for an extended period. They may limit pest populations over an entire season (or longer) or until climatic conditions or a lack of prey results in population collapse. Generally only one or two inoculative releases are made in a single season. In contrast, inundative releases involve large numbers of natural enemies that are intended to overwhelm and rapidly reduce pest populations. Such releases may or may not result in season-long establishment of natural enemies in the release area. Inundative releases that do not result in season-long establishment are the most expensive way to employ natural enemies because the costs of rearing and transporting large numbers of insects produce only short-term benefits. Such releases are usually most appropriate against pests that undergo only one or two generations per year.

The distinction between inoculative and inundative releases is not absolute. Many programs attempt to blend long-term establishment with short-term results. In addition, conservation and augmentation may be used together in a variety of ways to produce the best results.

Conservation

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Conserving natural enemies is often the most important factor in increasing the impact of biological control on pest populations. Conserving or encouraging natural enemies is important because a great number of beneficial species exist naturally and help to regulate pest densities. Among the practices that conserve and favor increases in populations of natural enemies are the following: (1) Recognizing beneficial insects. Learning to distinguish between pests and beneficial insects and mites is the first step in determining whether or not control is necessary. This circular provides general illustrations of several predators and parasitoids. Picture sheets available from the University of Florida feature common pests of many crops and sites. Insect field guides are useful for general identification of common species (see Borror and White, 1970). (2) Minimizing insecticide applications. Most insecticides kill predators and parasitoids along with pests. In many instances natural enemies are more susceptible than pests to commonly used insecticides. Treating gardens or crops only when pest populations are great enough to cause appreciable damage or when levels exeed established economic thresholds minimizes unnecessary reductions in populations of beneficial insects. (3) Using selective insecticides or using insecticides in a selective manner. Several insecticides are toxic only to specific pests and are not directly harmful to beneficials. For example, microbial insecticides containing different strains of the bacterium Bacillus thuringiensis (Bt), are toxic only to caterpillars, certain beetles, or certain mosquito and black fly larvae. Other microbial insecticides offer varying degrees of selectivity.

Other insecticides that function as stomach poisons, such as the plant-derived compound ryania, do not directly harm predators or parasitoids because these compounds are toxic only when ingested along with treated foliage. Insecticides that must be applied directly to the target insect or that break down quickly on treated surfaces (such as natural pyrethrins or insecticidal soaps) also kill fewer beneficials. Leaving certain areas unsprayed or altering application methods can also favor survival of beneficials. For example, spraying alternate middles of grove rows, followed by treating the opposite sides of the trees a few days later, allows survival and dispersal of predatory mites and other natural enemies and helps to maintain their impact on pest populations. (4) Maintaining ground covers, standing crops, and crop residues. Many natural enemies require the protection offered by vegetation to survive. Ground covers supply prey, pollen, and nectar (important foods for certain adult predators and parasitoids), and some degree of protection from weather. Most studies show greater numbers of natural enemies in no-till and reduced tillage cropping systems. In addition, some natural enemies migrate from woodlots, fencerows, and other noncrop areas to cultivated fields each spring. Preserving such uncultivated areas contributes to natural biological control.

Maintaining standing crops also favors the survival of natural enemies. Where entire fields are cut, natural enemies must emigrate or perish. Alternate strip cutting (with time for regrowth between the alternate cutting dates) allows dispersal between strips so that natural enemies remain in the field and help to limit later outbreaks of pests. (5) Providing pollen and nectar sources or other supplemental foods. Adults of certain parasitic wasps and predators feed on pollen and nectar. Plants with very small flowers are the best nectar sources for small parasitoids and are also suitable for larger predators. Seed mixes of flowering plants intended to attract and nourish beneficial insects are sold at garden centers and through mail order catalogs. Although no published data document the effectiveness of particular commercial mixes, these flower blends probably encourage a variety of natural enemies. The presence of flowering weeds in and around fields may also favor natural enemies.

Artificial food supplements containing yeast, whey proteins, and sugars may attract or concentrate adult lacewings, lady beetles, and syrphid flies. As adults these insects normally feed on pollen, nectar, and honeydew (the sugary, amino acid-rich secretions from aphids or scale insects), and they may require these foods for egg production. Lady beetles are predaceous as adults, but some species eat pollen and nectar when aphids or other suitable prey are unavailable. The proteins and sugars in artificial foods provide enough nutrients for some species to produce eggs in the absence of abundant prey. Wheast®, BugProTM, and Bug Chow® are a few of the artificial foods available from suppliers of natural enemies.

The practices listed above must be judged according to their impacts on pest populations as well as their effects on natural enemies. Practices that favor natural enemies may or may not lessen overall pest loads or result in acceptable yields. For example, reduced tillage favors beneficials but also contributes to infestations of such pests as the common stalk borer and European corn borer in corn. Moreover, tillage decisions may be influenced more by soil erosion and crop performance concerns than by impacts on pests or natural enemies. Flower blends and flowering weeds can serve as nectar sources for moths (the adult forms of cutworms, armyworms, and other caterpillar pests) as well as beneficials. The ultimate goal of conserving natural enemies is to limit pest problems and damage to crops, rather than simply to increase numbers of predators or parasitoids. Pest densities and crop performance are factors that must be included in any evaluation of the effectiveness of natural enemy conservation efforts.

Classical Biological Control

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Importing natural enemies from abroad is an important step in pest management in part because many pest insects in the United States and elsewhere were originally introduced from other countries.
Accidental introductions of foreign pests have occurred throughout the world as a result of centuries of immigration and trade. Although the foreign origins of a few recently introduced pests such as the Asian tiger mosquito, Russian wheat aphid, and Mediterranean fruit fly are often noted in news stories, many insects long considered to be serious pests in this country are also foreign in origin. Examples of such pests include the gypsy moth, European corn borer, Japanese beetle, several scale insects and aphids, horn fly, face fly, and many stored-product beetles. In their native habitats some of these pests cause little damage because their natural enemies keep them in check. In their new habitats, however, the same set of natural enemies does not exist, and the pests pose more serious problems. Importing and establishing their native natural enemies can help to suppress populations of these pests.

Importation typically begins with the exploration of a pest's native habitat and the collection of one or several species of its natural enemies. These foreign beneficials are held in quarantine and tested to ensure that they themselves will not become pests. They are then reared in laboratory facilities and released in the pest's habitat until one or more species become established. Successfully established beneficials may moderate pest populations permanently and at no additional cost if they are not eliminated by pesticides or by disruption of essential habitats.

Importation of natural enemies has produced many successes. An early success was the introduction of the Vedalia beetle, Rodolia cardinalis, into California in 1889 for the control of cottony cushion scale on citrus. For over 100 years this predaceous lady beetle from Australia has remained an important natural enemy in California citrus groves.

Although the importation of new natural enemies is important to farmers, gardeners, and others who practice pest management, the scope of successful introduction projects (involving considerable expertise, foreign exploration, quarantine, mass rearing, and persistence through many failures) is so great that only government agencies commonly conduct such efforts. Introducing foreign species is not a project for the commercial farmer or home gardener.

Types Of Biological Control

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Biological control, sometimes referred to as biocontrol, is the use of predators, parasitoids, competitors, and pathogens to control pests. In biological control, natural enemies are released, managed, or manipulated by humans. Without human intervention, however, natural enemies exert some degree of control on most pest populations. This ongoing, naturally occurring process is termed biotic natural control. Applied biological control produces only a small portion of the total benefits provided by the many natural enemies of pests.
There are three basic approaches to the use of predators, parasitoids, and competitors in insect management. These approaches are (1) classical biological control--the importation and establishment of foreign natural enemies; (2) conservation--the preservation of naturally occurring beneficials; and (3) augmentation--the inundative or inoculative release of natural enemies to increase their existing population levels. Broad definitions of biological control sometimes include the use of products of living organisms (such as purified microbial toxins, plant-derived chemicals, pheromones, etc.) for pest management. Although these products are biological in origin, their use differs considerably from that of traditional biological control agents.

Beneficial Insects and Mites

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Many insects and related arthropods perform functions that are directly or indirectly beneficial to humans. They pollinate plants, contribute to the decay of organic matter and the cycling of soil nutrients, and attack other insects and mites that are considered to be pests. Only a very small percentage of over one-million known species of insects are pests. Although all the remaining non-pest species might be considered beneficial because they play important roles in the environment, the beneficial insects and mites used in pest management are natural enemies of pest species. A natural enemy may be a predator, a parasitoid, or a competitor.

Rockwool, Geolite & DFT Irrigation

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Rockwool will allow the grower an easy set-up, since it is pre-formed and modular. It holds a tremendous amount of water and offers a buffer against drying in the case of electrical outages or pump failures. Rockwool slabs may be used successfully in a "hand-water" system since they stay moist so long. Rockwool will will maintain a 60/40 water to air ratio even when completely saturated, which makes for extremely healthy root growth. For starting seedlings and cuttings, rockwool is without equal. Rockwool is not degradable or reusable and must be repurchased for every use.

Geolite is a ceramic, kiln-fired pebble developed specifically for plant growth. It is completely inert and sterile and each piece is completely rounded so it will not cut roots. It is light weight and holds a small amount of moisture between irrigation cycles. It may be cleaned and reused again and again, so it is an economical choice. Geolite is not a good choice for most hand-water systems, as it does not provide enough of a moisture buffer. It may be difficult for anyone who is physically challenged to clean and rinse without assistance.

DFT Irrigation, or "media-less" culture, will be the most economical method of growing as it only requires 1" rockwool starter cubes. This can be an excellent choice for some growers, but beginners sometimes find that they are less successful with a media-less system as it does not buffer the roots against temperature changes, nutrient strength changes and uneven watering the way that rockwool and geolite will. This is a consideration for growers who experience frequent power outages and for beginners who will be more prone to initial mistakes, such as leaving a pump unplugged! Actual growth in these systems is excellent and DFT irrigation is a good choice for many conscientious growers.

Experiments to Try

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Many interesting experiments suitable for science fairs and for school or p-H projects can be performed with soilless culture. Two experiments, the first dealing with pH levels and the second with nutrient materials, are outlined here. You may want to work out variations of these experiments or try others of your own.

Experiment l: pH Levels
Use the nutrient solution given in the Nutrient Solutions section or a solution prepared from commercial premixed nutrients. Pour the solution into three containers. Adjust the pH of the solution in the first container to between 5.5 and 6.5. This solution is the "check" or "control" for the experiment. Lower the pH of the solution in the second container to less than 4.0 by adding small amounts of dilute sulfuric acid. Raise the pH of the solution in the third container to 8.0 or higher by adding a dilute sodium hydroxide (NaOH) solution. Test the pH of the solutions with an indicator.

The following plants do well at a pH range between 5.5 and 7.0: carrot, coleus, cucumber, geranium, orange, pepper, petunia, strawberry, turnip, and violet. Grow a plant from this list in each of the three solutions. Choose only one kind of plant (pepper, for example), and be sure the plants are about the same size. If you use seeds, plant them all at the same time.

Observe the difference in growth between the plants in the three solutions. Typical results are shown in Figure 1. You may want to set up various pl l ranges to find the best pH in which to grow a particular plant.

Figure 1. Effect of various pH levels on the growth of lettuce

Experiment 2: Nutrient Levels
You will need to prepare three nutrient solutions for this experiment. The first solution is a premixed nutrient solution or the "standard" solution listed in the nutrient solution tables. To prepare the second solution, use twice the recommended amount of each nutrient. For the third solution use one-half the recommended amounts of the nutrients. You will probably not want to prepare 25 gallons of each solution. The amounts of salts and water may be reduced by one-half, one-fourth, or even more as long as you mix the proper proportion of ingredients for each of the three solutions.

Be sure to grow the same kind of plant in each container so that you can compare results between the plants (Figure 2). If you transplant into these containers, choose plants that are uniform in size. By varying the nutrient and pH levels and observing the effects of these changes upon the plants, you can determine the proper pH and nutrient levels for a particular plant.

Figure 2. Effect of various nutrient levels on plant growth.

Principles Of Hydroponics Gardening

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Crops are grown in beds which are really shallow tanks or troughs that serve as a container for gravel or coarse sand. If there are several of these beds, they should be set up in a series at the same level and of a similar size.
These beds should be about 3 feet wide and any convenient length, although 100 feet is common. The sides are about 8 inches high and with a V bottom so the center is 11 or 12 inches deep at the center.
Beds intended to survive massive earthquake damage should be wooden frames lined with heavy vinyl sheeting. Pipes or other fittings should be plastic for increased flexibility and ease of repair.

This permits an arrangement whereby a half-tile or similar device through the center of the bed will feed or drain the solution rapidly from one end of the bed to the other. It is very important that the slope be precise, with no low areas from which solution will not drain.
Drainage in the beds is not only pointed toward the V bottom of the bed, but also toward one end of the bed, so that the V at the drain end is 2" lower than at the high end of the bed. This is a slight slope in the bottom of the trough.

There must be a pipe connection to the lowest point in the V at the drain end of the trough. The nutrient solution can then be pumped into the trough through that pipe and will drain out again when the pump has been shut off. The quantity of solution in the tank should be just sufficient to bring the water level up to within 1/2 to 1 inch of the top of the gravel or sand in the beds.
The entire hydroponics system is relatively simple to operate and may be made at least semi-automatic. In cool weather, pumping solution should be done once a day, but in warm, dry, or windy weather, it may be necessary 2 or 3 times a day. Installation of a time clock allows the start and stop of the pump to be automatically.
A centrifugal pump of sufficient capacity to fill beds in one-half hour is generally best for forcing the solution into the beds. With a centrifugal pump, the solution will flow by gravity through the pump back into the tank.

For those without a pump, a simple pail and flexible hose system to give the hydroponics beds their daily nutrient bath works well.

Gravel for the bed should be fairly uniform in texture, about 1/2 to 1/4 in diameter, and washed. If you use sand, it should be coarse and it also should be washed. Beds should be filled to within 1 inch of the top. The mix should be sterilized with heat or steam to prevent mildew and fungus problems.
Use the best seed for seedlings, planted in disease-free soil or sand and six inches or more high before transplanting. Loosen the planting media around the roots so that there will be as little injury as possible to the roots during transplanting. Rinse the planting media off the roots with water before planting in the hydroponics beds.
Supporting structures may be necessary to hold up the plants, as plants loaded with fruit, for example, are heavy. Do not attach supports to the ends of beds because the weight of the plants may warp the structure and cause leaks or draining problems. All supporting wires are suspended from overhead supports that are spaced at intervals alongside the troughs.

Cooling of the hydroponics area can be achieved by ventilation, as transpiration of moisture off the leave cools the plants just as perspiration cools the human body. Slats or windows that allow the air to circulate should be included in the arrangement.
Plants produce oxygen during the day, under lighted conditions, and carbon dioxide during the night. Hydroponics areas attached to living areas thus can oxygenate and cleanse the air of carbon dioxide, but should be closed off during the night so that oxygen is not depleted from the sleeping areas.
Pollination can be done either by bees or by hand, by manually shaking or tapping the flowers once a day, going flower to flower so as to spread the pollen. Pollination helps increase fruit yield, and for some produce makes the difference between a high yield or no yield at all.

New Research

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Ongoing research with plants such as tomatoes in floating systems indicate that larger plants require more above-water rooting volume (more air-space) in order to produce successful yields. To produce more root mass above the water, you may want to test a system that uses two stacked styrofoam floats with holes drilled in the bottom one and all but a six-inch edge around the perimeter cut out of the top one. Fill the empty top float with perlite, vermiculite, or other hydroponic media and plant vegetables or flowers into it the same way you would plant a normal garden. Preliminary results show this method to be promising if starter fertilizer is used on the young plants until their roots reach the fertilized hydroponic solution below the floats.

Requirements for Plant Growth

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Hydroponic systems will not compensate for poor growing conditions such as improper temperature, inadequate light, or pest problems. Hydroponically grown plants have the same general requirements for good growth as field-grown plants. The major difference is the method by which the plants are supported and the inorganic elements necessary for growth and development are supplied.

Temperature. Plants grow well only within a limited temperature range. Temperatures that are too high or too low will result in abnormal development and reduced production. Warm-season vegetables and most flowers grow best between 60° and 75° or 80° F. Cool-season vegetables such as lettuce and spinach should be grown between 50° and 70° F.

Light. All vegetable plants and many flowers require large amounts of sunlight. Hydroponically grown vegetables like those grown in a garden, need at least 8 to 10 hours of direct sunlight each day to produce wells Artificial lighting is a poor substitute for sunshine, as most indoor lights do not provide enough intensity to produce a crop. Incandescent lamps supplemented with sunshine or special plant-growth lamps can be used to grow transplants but are not adequate to grow the crop to maturity. High intensity lamps such as high-pressure sodium lamps can provide more than 1,000 foot-candles of light. The serious hobbyist can use these lamps successfully in areas where sunlight is inadequate. The fixtures and lamps, however, are very expensive and thus not feasible for a commercial operation.

Adequate spacing between plants will ensure that each plant receives sufficient light in the greenhouse. Tomato plants pruned to a single stem should be allowed 4 square feet per plant. European seedless cucumbers should be allowed 7 to 9 square feet, and seeded cucumbers need about 7 square feet. Leaf lettuce plants should be spaced 7 to 9 inches apart within the row and 9 inches between rows. Most other vegetables and flowers should be grown at the same spacing as recommended for a garden.

Greenhouse vegetables, whether grown in soil or in a hydroponic system, will not do as well during the winter as in the summer. Shorter days and cloudy weather reduce the light intensity and thus limit production. Most vegetables will do better if grown from January to June or from July to December than if they are started in the fall and grown through the midwinter months.

Water. Providing the plants with an adequate amount of water is not difficult in the water culture system, but it can be a problem with the aggregate culture method. During the hot summer months a large tomato plant may use one-half gallon of water per day. If the aggregate is not kept sufficiently moist, the plant roots will dry out and some will die. Even after the proper moisture level has been restored, the plants will recover slowly and production will be reduced.

Water quality can be a problem in hydroponic systems. Water with excessive alkalinity or salt content can result in a nutrient imbalance and poor plant growth. Softened water may contain harmful amounts of sodium. Water that tests high in total salts should not be used. Salt levels greater than 0.5 millions or 320 parts per million are likely to cause an imbalance of nutrients. The amateur chemist may be able to overcome this problem by custom mixing the nutrient solutions to compensate for the salts in the water.

Oxygen. Plants require oxygen for respiration to carry out their functions of water and nutrient uptake. In soil adequate oxygen is usually available, but plant roots growing in water will quickly exhaust the supply of dissolved oxygen and can be damaged or killed unless additional air is provided. A common method of supplying oxygen is to bubble air through the solution. It is not usually necessary to provide supplementary oxygen in aeroponic or continuous flow systems.

Mineral Nutrients. Green plants must absorb certain minerals through their roots to survive. In the garden these minerals are supplied by the soil and by the addition of fertilizers such as manure, compost, and fertilizer salts. The essential elements needed in large quantities are nitrogen, phosphorus, potassium, calcium, magnesium, and sulfur. Micronutrients - iron, manganese, boron, zinc, copper, molybdenum, and chlorine are also needed but in very small amounts.

Support. In a garden the plant roots are surrounded by soil that supports the growing plant. A hydroponically grown plant must be artificially supported, usually with string or stakes.

Introduction for Hydroponics

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IN RECENT YEARS GROWING PLANTS HYDROPONICALLY--that is, with the roots in a medium other than soil--has stirred the imagination of many persons interested in plant growth and development. Commercial growers have adopted hydroponic methods to produce crops in circumstances that would otherwise be unfavorable. For the plant hobbyist, hydroponics offers an opportunity to learn more about the growth of plants and their interactions with their environment. Gardeners may grow flowers, ornamental plants, and vegetables by hydroponics. Growing your own fresh vegetables out of season can be a special winter treat.

Colorful sales campaigns and articles in the popular press have led people to believe that hydroponics is a new discovery that will revolutionize modern agriculture. However, the basic techniques have been used by plant researchers for well over a century to determine the effect of particular nutrients on plant growth and yield. The first recorded experiments were conducted in England in 1699 by Woodward. By the mid-nineteenth century, Sachs and Knop, pioneers in this field, had perfected a method of growing plants without soil. In the late 1920s and early 1930s Gericke was able to grow plants successfully on a large scale by adapting the laboratory technique of solution culture.

The widespread use of hydroponics for commercial plant production is a relatively recent occurrence. In areas where soil is lacking or unsuitable for growth, hydroponics offers an alternative production system. However, there is nothing magical about hydroponics. Equally good crops can be produced in a greenhouse in conventional soil or bench systems, often at lower cost.

Pest Control

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The control of plant pests has always been a contentious issue and we would assume that the majority of serious growers would like to avoid the use of toxic chemicals wherever possible. Like every other aspect of plant rising, there have been many changes in recent years. These have been tested and fines tuned by professional growers and are now becoming available to the amateur gardener. Amongst the new technologies, the idea of biological pest control must take pride of place. Like all great concepts, it is simple yet effective and is causing major changes to the way we do things. Biological pest control is one of the most exciting developments in modern horticulture and it offers a vision of a pesticide free future when man can use nature’s own weapons to grow his food in an uncontaminated atmosphere and a cleaner, greener world. Basically, biological pest control involves the introduction of friendly creatures to combat the ones that do the damage. These creatures are known as predators because they feed on the pest at some stage in its life cycle.

Two-spotted Mite (Spider Mites)

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These little creatures, almost invisible to the naked eye, are undoubtedly the greatest menace to the grower. They are often unseen and unsuspected until their numbers are high and they can multiply at a devastating rate. If they find favourable conditions in the greenhouse or indoor growroom they can literally destroy a crop.

The first signs of their presence are small dead spots that appear in clusters on the affected leaves. This is followed by a general bronzing of the foliage and as the infestation increases, there will be visible deposits of fine webbing on the underside of leaves. Old fashioned methods of chemical control have never been successful for long as these creatures are very adept at developing resistance to each poison in turn. Man has responded by using ever more toxic chemicals to control them with an ever decreasing success rate. The side effects of this are the collateral destruction of hundreds of beneficial or neutral insects that would normally co-exist with the mites in some sort of balance.

The solution that biological pest control offers is the introduction of another mite called Phytoseiulus Persimilis which lives exclusively on two-spotted mites. If the population of pests is at a high level, the predator will multiply in relation to its food supply. Once the pest is reduced then the predator will begin to die out as well. A balance should then be achieved which will maintain the pest population at low levels, below the point at which they will cause visible damage. If the pests do begin to multiply beyond the predators’ capacity to consume them, the grower can then make small adjustments to the environmental conditions (temperature and humidity) that will favour the predators over the pests. Predator mites are known commercially as SPIDEX and can be purchased at Esoteric Hydroponics.

Humidity

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Humidity is another important consideration in grow room management. If it is allowed to get too high for prolonged periods, it will cause problems both in your room and amongst your plants. The main danger is the development of Botrytis or grey mould amongst the flowers or fruit. This organism thrives in conditions of high humidity and will quickly spread and ruin a crop. Plants of the melon family and strawberries are particularly susceptible to fungal diseases and should be provided with a dry environment. The cautious grower will always monitor the humidity in his grow room which is measured by another simple device called a hygrometer. This is a dial type instrument that can be mounted on the wall next to the Max-Min thermometer and give a constant and accurate reading of humidity. The ideal humidity for normal plant rising would not be much above 50%. If it rises above this, the grower will normally operate his extractor fan until it has been reduced. To keep this potential problem under check, it is advisable to avoid leaving water on the floor which can then evaporate and raise humidity. Any water or nutrient solution that spills or overflows should be wiped up promptly and nutrient tanks should be covered at all times. Any water that is left exposed to the heat from your grow lights will rapidly evaporate and add to the humidity levels. Keep your greenhouse or grow room dry.

The Pest: Whitefly

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First Signs: Tiny, pure white "moths" resting on leaf surfaces. When the leaves of the plant are disturbed, these moth-like white flies quickly flutter up, then settle back down onto plants.
Leaves may appear shiny with honeydew. A magnifier reveals clear-white "scales" (the pupae) on the undersides of leaves. All life stages of the Whitefly literally suck the water out of plant leaves.
Most Common Species:
Greenhouse Whitefly & Sweet Potato Whitefly. It's so difficult to be certain which species you have that we advise either consulting your county agent to be sure, or simply widening your predator strategy to cover both species - it's not uncommon to have both pests together.

Common Problems

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Note: Always check the pH and adjust if necessary to 5.8 - 6.3. Check and maintain an optimum nutrient level.

NITROGEN (N)
Save the Plant : Add fertilizer containing N. It may take up to a week for this treatment to work.

PHOSPHORUS (P)
Save the Plant: Add fertilizer containing Phosphorus. New growth will appear to be normal but already affected leaves will not recover.

POTASSIUM (K)
Save the Plant: Add fertilizer containing K.

BORON (B)
Save the Plant: Use a teaspoon of Boric acid per gallon of water.

CALCIUM (Ca)
Save the Plant: Foliar feed the plants with one tsp. of dolomite lime or one tsp. of kelp per quart of water until condition improves.

IRON (Fe)
Save the Plant: Foliar feed with a fertilizer containing Fe. (#6 of our Six Pack)

MAGNESIUM (Mg)
Save the Plant: Foliar feed with a liquid fertilizers containing Mg. Increase pH.

MANGANESE (Mn)
Save the Plant: Foliar feed with any fertilizer containing Manganese.

MOLYBDENUM (Mb)
Save the Plant: Foliar feed with a fertilizer containing Mb.

SULPHUR (S)
Save the Plant: Mix one tablespoon of Epsom salts (#5 of our Six Pack) per gallon of water until the condition improves.

ZINC (Zn)
Save the Plant: Apply a fertilizer containing Zn.

Hydroponic Science Projects - An Introduction

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Please do note that hydroponics works really well because the gardener provides everything the plants need. So by cutting down to the very basic needs for a hydroponic system we actually give the plants a disadvantage.

Requirements

When doing a science project on hydroponics, these are the very basic things you need:

> A garden system
> growing medium
> A & B nutrient
> pH kit
> Seeds
> A bucket
> Piece of water hose, attached to the bucket and to your tray

With hydroponics the gardener usually also provides the light. If you have a grow light, use it. If you don’t make sure the plants get ample sunlight.

A standard 2 part nursery tray and a bucket can be easily rigged to a 'flood & drain' garden.

A hydroponics growing medium is completely inert. An inert medium will not effect the pH of the nutrient solution. It does not provide anything but an anchor for the plant. Hydroponic growing mediums are less compact than earth so the roots get more air.

The growing medium we suggest for a project is ‘Rockwool’. Get one inch / 2.5 cm starter cubes.

Any commercially prepared standard 'hydroponic nutrient' should do nicely.

Plants will fail if their pH is too high or low. You need something to test the pH level of your nutrient solution and pH adjusters.

Try an herb such as basil, it will grow and flower quickly. Leaf lettuce is another good plant to use because we harvest before it flowers. Stay away from tomato, pepper, cucumber because they take a very long time to fruit.

Preparation

The first step is to pH balance the Rockwool starting cubes. pH refers to acid or alkaline level of the solution. The pH scale goes from one to fourteen, with seven being neutral. Any reading above seven is alkaline, any reading below seven is acidic. Tap water tends to be a little on the alkaline side and since plants prefer a slightly acidic root zone, we must add a little acid to the water we feed the plants.

Fill a one litre container with tap water. Pour about one tablespoon of the water into a small clear container. With an eye dropper add two drops of pH indicator solution to the water sample. Now compare the colour of the sample to the colour chart on the bottle. It will probably be greenish (pH 7-8). Next add two or three drops of ‘pH Down" (phosphoric acid) to the litre of water, stir and do the test again. Repeat this procedure until the sample turns yellow, indicating a pH of about 6.0. If the colour of the sample turns brownish or reddish, you have added too much pH Down, so just add more tap water to raise the pH level again. Be careful not to get any pH Down on your hands. If you do, wash immediately with water.

Set up the hydroponic system

Put the garden in the place where it will remain. It is not easy to move when it is in use. Make sure the garden is on a sturdy, level surface where it can’t be knocked over. When mounting on a window ledge make sure the ledge is wider than the garden.

Rockwool must not sit on a flat surface, there must be an air space underneath. Prop up, use ½" of Perlite or a standard 2 part nursery tray.

Attach the hose to the tray and bucket.

Plant seeds

Now you are ready to soak your one inch starter cubes in the pH balanced solution and put them on a plate or tray. It is now time to plant your seeds! Choose your seeds and insert one seed into the small hole in the top of each cube. If there is not a pre-made hole, make one about pencil width, a quarter inch / 0.75cm deep. Cover the hole with a bit of Rockwool so the seed has a dark place to sprout from. Take a small piece of saran wrap or plastic bag and cover the cubes to keep the moisture in. In a couple of days wet the cubes again with your pH balanced water.

Most seeds will begin to sprout in four to six days. Once they have sprouted, remove the saran wrap and moisten the cubes again.

Mix the nutrients

The nutrients are the plant’s source of food so it is important that we do not give them too much or too little. The hydroponic nutrients supply all of the mineral elements that plants otherwise would get from the soil. Since your plants are still very young, mix the nutrient solution at half strength this time.

So use 2.5 ml of each the ‘A’ and ‘B’ nutrient per litre (Check the instructions on your nutrients.). Mix enough solution to fill your tray to ¾ rd of the height of the Rockwool cubes.

pH balance the solution

This process is identical to the procedure for preparing the seeding cubes. Always adjust the pH level after mixing the nutrients as they will also lower the pH a little.

Flood and Drain your garden

Raise the bucket above the garden so the nutrient solution will flow into the tray.

The tray should be flooded to ¾ of the cubes’ height and drain immediately after. Make sure to not submerge the roots for more than 3 minutes.

Repeat this 2 to 3 times per day.

Maintenance of your nutrient solution

Plants use more water than nutrients, therefore top up the bucket with fresh water daily and pH balance the solution to 6.0 / 6.5.

Make a new solution each week. After the first week use ¾ strength nutrients, a week later you can start mixing a full strength solution.

This Flood and Drain technique exposes the roots directly to the nutrient solution. Erratic pH and EC (the amount of dissolved salts in the solution) is caused by the roots acting directly on the nutrient solution. Plants will benefit greatly by keeping these levels steady.

Light

Remember that light is very important. If your plants don’t have light, it doesn’t matter what you give them.

AEROPONIC

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The aeroponic system is probably the most high-tech type of hydroponic gardening. Like the N.F.T. system above the growing medium is primarily air. The roots hang in the air and are misted with nutrient solution. The mistings are usually done every few minutes. Because the roots are exposed to the air like the N.F.T. system, the roots will dry out rapidly if the misting cycles are interrupted.

A timer controls the nutrient pump much like other types of hydroponic systems, except the aeroponic system needs a short cycle timer that runs the pump for a few seconds every couple of minutes.

N.F.T. (Nutrient Film Technique)

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This is the kind of hydroponic system most people think of when they think about hydroponics. N.F.T. systems have a constant flow of nutrient solution so no timer required for the submersible pump. The nutrient solution is pumped into the growing tray (usually a tube) and flows over the roots of the plants, and then drains back into the reservoir.

There is usually no growing medium used other than air, which saves the expense of replacing the growing medium after every crop. Normally the plant is supported in a small plastic basket with the roots dangling into the nutrient solution.

N.F.T. systems are very susceptible to power outages and pump failures. The roots dry out very rapidly when the flow of nutrient solution is interrupted.

DRIP SYSTEMS (RECOVERY / NON-RECOVERY)

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Drip systems are probably the most widely used type of hydroponic system in the world. Operation is simple, a timer controls a submersed pump. The timer turns the pump on and nutrient solution is dripped onto the base of each plant by a small drip line. In a Recovery Drip System the excess nutrient solution that runs off is collected back in the reservoir for re-use. The Non-Recovery System does not collect the run off.

A recovery system uses nutrient solution a bit more efficiently, as excess solution is reused, this also allows for the use of a more inexpensive timer because a recovery system doesn't require precise control of the watering cycles. The non-recovery system needs to have a more precise timer so that watering cycles can be adjusted to insure that the plants get enough nutrient solution and the runoff is kept to a minimum.

The non-recovery system requires less maintenance due to the fact that the excess nutrient solution isn't recycled back into the reservoir, so the nutrient strength and pH of the reservoir will not vary. This means that you can fill the reservoir with pH adjusted nutrient solution and then forget it until you need to mix more. A recovery system can have large shifts in the pH and nutrient strength levels that require periodic checking and adjusting.

EBB AND FLOW (FLOOD AND DRAIN)

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The Ebb and Flow system works by temporarily flooding the grow tray with nutrient solution and then draining the solution back into the reservoir. This action is normally done with a submerged pump that is connected to a timer.

When the timer turns the pump on nutrient solution is pumped into the grow tray. When the timer shuts the pump off the nutrient solution flows back into the reservoir. The Timer is set to come on several times a day, depending on the size and type of plants, temperature and humidity and the type of growing medium used.

The Ebb and Flow is a versatile system that can be used with a variety of growing mediums. The entire grow tray can be filled with Grow Rocks, gravel or granular Rockwool. Many people like to use individual pots filled with growing medium, this makes it easier to move plants around or even move them in or out of the system. The main disadvantage of this type of system is that with some types of growing medium (Gravel, Growrocks, Perlite), there is a vulnerability to power outages as well as pump and timer failures. The roots can dry out quickly when the watering cycles are interrupted. This problem can be relieved somewhat by using growing media that retains more water (Rockwool, Vermiculite, coconut fiber or a good soiless mix like Pro-mix or Faffard's).

WATER CULTURE

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The water culture system is the simplest of all active hydroponic systems. The platform that holds the plants is usually made of Styrofoam and floats directly on the nutrient solution. An air pump supplies air to the air stone that bubbles the nutrient solution and supplies oxygen to the roots of the plants.

Water culture is the system of choice for growing leaf lettuce, which are fast growing water loving plants, making them an ideal choice for this type of hydroponic system. Very few plants other than lettuce will do well in this type of system.

This type of hydroponic system is great for the classroom and is popular with teachers. A very inexpensive system can be made out of an old aquarium or other water tight container.

WICK SYSTEM

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The Wick system is by far the simplest type of hydroponic system. This is a passive system, which means there are no moving parts. The nutrient solution is drawn into the growing medium from the reservoir with a wick. Free plans for a simple wick system are available (click here for plans).

This system can use a variety of growing medium. Perlite, Vermiculite, Pro-Mix and Coconut Fiber are among the most popular.

The biggest draw back of this system is that plants that are large or use large amounts of water may use up the nutrient solution faster than the wick(s) can supply it.

Nutrients And Additives

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As with all hydroponic systems, it is only as good as the food that you use. Below are listed and illustrated the leaders in the nutrient market. It is our belief that some nutrient in some cases give better performance or pH stability than others. However personal preference and subjectivity rules the day. A lot of the time its like asking what’s better? Red or white wine? Bitter or larger? It depends apparently on what your eating with your drink! Well if you believe that then your believe anything. Hydroponics is the same if you find a nutrient you like and you believe it performs well then stick with it. If you are unhappy with your results then experiment with another make or a combination of makes and products, your got nothing to lose.

Nutrients are very important in hydroponics. They are the sole source of nutrition for your plants and you should always feed your plants with the best there is available. At Esoteric Hydroponics, we take our nutrients very seriously and can assure you that we only have on offer the best that there is available on the market today. Generally speaking, there are hydroponics nutrients (for young plants and vegetative growth) and bloom nutrients (flowering and fruiting). Formulations are available for all of our nutrients. Also, we offer hard water and soft water formulations for many of our nutrients to suit the various water types around the UK and to ensure your growing success.

NFT Hydroponics System

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This was the original pioneering hydroponics technique. Although dated, it is still very popular among indoor horticulturists, mainly due to the inexpensive cost of setting up a NFT system but also its simplicity.

The principle is very easy to grasp. The plants are grow in a constant flow of nutrient enriched water. The water is spread out so as to flow in approximately 1-3mm of depth over a flat surface. This creates a film of water, which flows over the root system of the plant. This is not a rapid flow but enough of a flow that the water is in constant motion. Water is fed to the table via a submersible pump from the top end of the table.

As the water is pumped in at one end of the table, it slowly makes its way to the bottom of the table where it then returns back to the tank in which the pump is submerged. So you get constant exchange of the water in the tank being pumped from one end of the table then returning to the tank via the other end of the table. The film of nutrient should always be maintained at around 1 to 3mm of water. The roots of the plant should grow below and above the water’s surface that is why the film should be constant, allowing the water roots to develop below the water’s surface, and also allowing the air roots to grow above the water’s surface.

The draw back of this system is that as the roots are constantly submerged in a film of water, this prohibits the aeration to the root ball, which in turn prohibits outrageous performance. To get over this problem, some NFT growers put the pumps on cycles effectively flood and draining their NFT system, other growers put air stones in the water tank and even under their plants on the NFT tables. Most NFT growers administer H202 to their tanks but at a very dilute ratio, however this really needs to be done on a daily basis as dilute H2O2 breaks down very rapidly and over the course of 24 hours has completely dissolved its active ingredients. In using H2O2 in a daily capacity this prohibits the use of organic growth promoters and other products that reduce the possibility of bacterial break out like pythium.
The main draw back with NFT systems, especially in a grow room environment is the fact that pump failure is likely to strike at some point. The reason this tends to happen is that NFT systems are packaged with small flow rate pumps; cheap springs to mind but this is not technically fair. The plants only need a small delivery of water at a constant rate and the small pumps are all that can be used on a small NFT system. Now as the pump is perpetually on, the pump sees a lot of action over the course of its life. This coupled with the fact that you are then adding dissolved salts in the tank and in turn you are possibly in a hard water area, you get precipitation of the salts and the calcium that build up on get precipitation of the salts and the calcium that build up on and around the impeller of the pump. Once this impeller begins to attract precipitation it is not long until it either gives up spinning completely or that it does not deliver enough water to satisfy the plants’ needs, resulting in crop failure. Pump failure can be overcome through regular cleaning and maintenance of the pump or indeed regular replacements of the pumps, as mentioned earlier these are very inexpensive pumps and therefore can be regularly replaced without financial worry.

Another drawback with this technique is dude to the fact that the roots are constantly submerged in water the plants are very prone to bacterial disease like pythium. Again this can be overcome via regular dumping of the nutrient tank and adding products to the nutrient solution that have active ingredients that minimise the threat or root rot and moulds.

The last drawback is that heavy yielding plants tend to fall over in a NFT system. This is due to the fact that the roots grow out flat and long giving the plants no stability. As they grow older and bigger you will need to support the fruits or flowers otherwise they simply topple over. Supporting them is easy using yo-yos, string, canes or some growers use a scrog. This simple netting stretched out over the growing area. The plants then grow up through this netting which in turn helps support the plants.
All of the above to one side, these systems are very productive and are an excellent inexpensive teaching aid to the principle of hydroponics. Also with this beautiful innovation the world of hydroponics might not be with us as this technique was the first adopted and used by many growers all over the planet paving the way for our very own hydroponics revolution. One has to take one’s hat off to the British inventor that pioneered this technique. I mean, what made someone think: I know let’s grow plants in a soil-less medium using nothing but a film of nutrient to do it in. Off the wall you could say!

Hydroponic Systems

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There are many hydroponic techniques on the market, NFT, Flood and Drain, Drip Irrigation, Aeroponics, Passive, and all these can be recirculating or run to waste.

Confused? You should be. Esoteric Hydroponics sells them all but for sanity's sake we have illustrated by far the most practical, easy to use, most popular systems on the market. These are, Nutrient Film Technique and Flood and Drain aka Ebb and Flow systems. The NFT system suits smaller budgets, gives good performance and is easy to use, however, it has a couple of drawbacks. These are lack of aeration to the root ball resulting in restricted results, lack of support for your heavy yielding plants resulting in you having to string or support your plants by whatever means you can think of. If pump failure strikes and you are away for the day with your lights on, it's kick the bucket time for your beloved plants. Apart from these drawbacks, which can be overcome, NFT cannot be mocked as its creation sparked the whole hydroponics revolution.
However, hydroponics has evolved a bit since NFT. For example, the Flood and Drain Pod system has taken the drawbacks of all the other hydroponics systems available on today's market and has overcome them in one fell swoop. Outrageous aeration to the rootball; superb support for your heavy yielders; at least three days grace if pump failure strikes, even if lights are constantly on; built-in overflow so no spills, modular - can be rebuilt to fit the most awkward spaces, hidden reservoir so no waste of valuable grow room space, a large capacity reservoir for reduced visits. As well as stupendous performance, it is becoming the definitive indoor hydro system and yes, even the largest 24 podder will fit through a loft hatch. All your concerns dealt with in one comprehensive technique - the Pod System™, invented, designed and manufactured by Esoteric Hydroponics.

What is Hydroponics?

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Simply enough, hydroponics, sometimes referred to as hydro culture, is the process of growing plants without soil. It applies to flowers, trees, shrubs, vegetables and grains. Under that broad definition there are many variations of hydroponic practice in existence. As a general rule, more hydroponic growing is done indoor than outdoors, but this is because the main use of hydroponics to this stage has been commercial. There are few reasons why you should not use hydroponics outdoor if you wish and if you use the Autopot System, even those few reasons can be overcome or made much less of a problem.

Desktop Garden

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Some of the easiest plants to grow include cacti and succulents. They don't need a lot of attention--they like low humidity, lots of light and a little bit of water. With a little creativity, you can design wonderfully low-maintenance desktop gardens.

To start with, you need a container. A shallow container, about two inches deep, works best. Terra cotta is always a nice option. For a planting medium, you can buy a cacti mixture, or you can mix your own: half sand, half potting soil.
Now you're ready for the plants. Design your garden in odd numbers to get a better pattern. And of course, for this project, remember to wear gloves so you won't get pricked. Arrange your plants and add rocks to help anchor the plants.

Let the cacti dry out in between waterings--you may have to water only every six weeks. Keep your container garden in a sunny location, like a sill or a desk, and simply enjoy.

Future Work

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More work should be done to size and specify full-scale greenhouses, including retractable roof designs. Side vent placement to prevent plant damage and short-circuiting to the first roof vent is still being evaluated. Alternative shading techniques such as internal nets are also being studied for use in naturally ventilated greenhouses in both humid and arid desert climates. While span width studies have been limited by computer memory and speed, this problem is changing with each new computer.

How Natural Ventilation Works in Greenhouse

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Natural ventilation in greenhouses functions primarily by wind blowing in one side and out the other. Wind can also create a vacuum pressure along the roof to “suck” the air out while letting air in the same vent or into the side vents. A secondary, much smaller effect is that of buoyancy, which predominates on hot, low wind days. In all cases, it is important to have at least one very effective inlet with multiple outlets; and that the air moves from inlet to outlet through the plants for good ventilation. For gutter-connected multi-spans, a combination of windward side vents and continuous leeward roof vents tends to result in the most effective ventilation design. For retractable roof designs, open windward side vents are as important as the open roof area to achieve mid-summer cooling.

History of Hydroponics

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Experimenting with plant nutrients began over three hundred years ago. An English scientist, named John Woodward, experimented with plant nutrients. He wanted to know whether plants got their nutrients from the soil or the water. He began with plants in water and slowly added soil to the water each day. He discovered that the plants improved in size and health. He concluded that it was the soil, and the water which provided the nutrients for the plants.

However, his findings contradicted those of the farmers. Farmers believed that the soil only provided stability for the plants to root on to. This belief was based on their experiences with droughts. Without water, the crops died, no matter how rich in nutrients the soil was.

This was the beginning of many more experiments on plant nutrition. Discoveries and new wonderings which followed Woodward's investigations, led to what we now acknowledge as the science of hydroponics.

Today, many of the different methods of hydroponic gardening comes from the ideas of Dr. Gerike, a plant professor at the University of California at Davis. Dr. Gerike became famous with producing tomato plants 25 feet tall through his method of soilless gardening. In fact, Dr. Gerike was the person who named the science of soilless gardening, "hydroponics."

Hydroponics, growing and cultivating plants without soil, has been in existence since ancient civilization. The Egyptians, Inca Indian tribes, the Aztecs, and the Babylonians are examples of ancient civilizations which practiced hydroponic gardening without even realizing it,way before the word "hydroponics" was ever thought of. Although many of us think of hydroponics as a relatively new method in agriculture, our ancestors, in their efforts to always improve their technology in farming, have already been working and learning whatever their gardens could teach them, including soiless gardening. There, however, remains a lot be learned in the science of hydroponic gardening. Because of its low cost and easy workload, hydroponics captures the interest of many gardeners. New methods in hydroponic gardening are always being explored and will continue to be studied by other gardeners.

Seed Germination

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Large seeds can be planted directly into aggregate culture systems or devices such as the Pipe Dream and thinned later. Plants with small seeds should be transplanted into the system to insure a good stand. With the water culture method, all plants must be transplanted to the system.

Seedlings to be transferred can be grown with their roots exposed or in root cubes. It is best to grow them with exposed roots if they are to be grown in a water culture or aeroponic system. Sow the seeds in quartz sand, coarse vermiculite, or perlite. Water them and cover them with wet paper towels or cheesecloth until they germinate. Then remove the covering and thin the plants. Moisten them as needed with a dilute nutrient solution rather than water because the germination medium does not provide adequate nutrition. A one-fourth concentration of the nutrient solution recommended in the next section may be used. When the seedlings are large enough to transplant, gently wash the growing medium from their roots. Do not be concerned if a few pieces of the medium remain on the roots.

Seedlings for the PVC pipe or NFT system should be grown in sterile root cubes, which are composed of expanded plastic foam, cellulose fiber, or a compressed mixture of peat and vermiculite. These cubes provide weight and help support the plant in the tube. Peat-lite mix or peat pots should not be used as they will disintegrate, and the particles may clog the pump that circulates the nutrient solution. Oasis Rootcubes and Horticubes are examples of commercially available root cubes.