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

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.