Applying fertilizer routinely without knowing whether it is needed can result in poor fruit quality and excessive tree growth. Excessive fertilization can also waste money and contribute to environmental pollution.
Annual soil analyses can keep you informed about the nutrients in the soil and the soil acidity. In addition to soil analyses, simple observation of the amount of vegetative growth can help in managing soil fertility. Trees with less than 10 to 12 inches of current season's growth on lateral branches may need fertilizer. On the other hand, trees with greater than 18 inches of growth may not need fertilizer for several years. Excessive tree growth can promote some pest problems.
If you must fertilize without the benefit of a soil test or other information, a useful rule of thumb is to apply 3/4 to 1 pound of 10-10-10 fertilizer for each year of tree age. When fertilizer is used, it is usually applied in late winter. Fertilizer should be broadcast on the soil surface both inside and outside the drip line of the tree. Keep fertilizer at least 6 inches away from the trunks of young trees. In areas with sandy soils, apply 1/2 of the recommended amount of fertilizer in late winter and the remainder in May. If the crop is lost due to frost, do not apply the second half.
© Erv Evans, Consumer