Air Circulation

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.