2.  Phosphorus Deficiency
 Plants that are starved for phosphorus are stunted, and darker than usual. The leaves are dull and gray-green, and may be tinged with magenta. Some plants develop magenta coloring under the leaves, especially on the veins or around the edges of leaves. Flowering and fruiting are usually poor. Plants that are only slightly deficient in phosphorus grow more slowly than normal, and produce fewer flowers and fruit, but often have no specific symptoms.

Phosphorus in the plant: Phosphorus is used in the enzyme systems that produce new cells and supply energy to the plant tissues. It promotes healthy root growth and the production of flowers and fruit.

Seedlings: Seedlings and other plants with limited root systems need more phosphorus than plants with more developed root systems. Even in areas where phosphorus seldom needs to be applied to growing plants, seedlings may be deficient. If this is the case, their growth is slowed for a few weeks until the root system develops enough to supply the plant with phosphorus. Trees seldom need added phosphorus.