Fertilizing your trees to promote faster growth may seem like the logical thing to do, however, this is not always the case. Ornamental trees may require fertilizing because many grow under poor conditions having to tolerate extensive pruning, large areas of pavement and concrete, and sod cover which can use up most of the available nutrients and moisture. On the other hand, shelterbelts usually grow under better soil conditions. There is no general agreement on the best formulation of fertilizer for trees, however, it is agreed that the fertilizer should contain the three major elements, N, P and K. Nitrogen will move downward in the soil, however, phosphorous and potassium move very little in the soil.
Trees have a deep and extensive root system as compared to annual plants.
Occasionally the roots will extend 1 to 3 times beyond the dripline. Fertilizer must be placed near the feeding roots so that it is available to the tree. The recommended method of doing this is discussed below. The fertilizer is put into many holes placed around the tree and then the holes are filled in with peat moss, shredded manure, or topsoil. The holes should be 1 to 2 feet deep, about 2 feet apart and slanted toward the tree.