Home & Garden Tips
Fertilizing fruit trees not a simple task
By Roosevelt McWilliams County Extension Agent

Have you ever felt like somebody was hedging a little when you tried to get a straight forward recommendation for fertilizing peaches, apples, pears and plums? It's easy to come up with a fertilizer recipe for lawns, shrubs, yard trees and most other landscape plants that will work for most gardens, not so with fruit trees.

With the other plants, the greatest concern is the health and appearance of the plant. With fruit trees, we have to look at moderate vigor, quality of fruit, and adequate flower-bud formation for a good crop. What you do for one of these tree fruits responses might negatively affect other responses you want. Here are some rules to follow for fertilizing fruit trees.

+ Always adjust the soil pH to 6.5 before you plant. Have your soil samples analyzed to find out how much lime is needed.

+ Don't put fertilizer in the planting hole. Fertilize granules that come in direct contact with the roots may kill the tree.

+ During the first year, fertilize the trees with a balanced fertilizer often (early April, mid-May, early July) with a small amount of fertilizer. One-half to one cup of 10-10-10 evenly scattered over a circle 2 feet across should be about right.

+ The second year, double the circle diameter and the fertilizer rate. Fertilize three times: early March, early May, and early July.

+ The third year of the tree's life is a year of transition from a vigorous, nonfruiting tree to a nearly mature tree. So only fertilize it twice, in early March and late May. One pound of 10-10- 10 each application evenly scattered over a circle 6 to 8 feet across is ideal.

+ In the first three years of the tree's life we were only concerned about tree health.

Now that the tree is ready to begin fruiting, though, we must balance moderate tree vigor with quality fruit production and flower-bud formation.

Moderate tree vigor is critical. Too much vigor results in poor fruit quality and too little vigor results in small fruit.

You should keep annual records on how much fertilizer you applied, the vigor of the tree and the size and quality of the fruit. Average shoot growth of 8 to 12 inches for apples and pears and 15 to 20 inches for peaches, nectarines and plums is about ideal if you have a crop of fruit.

For example, if you put 4 pounds of 10-10-10 (early March only) on your trees and got ideal growth and fruiting, do the same thing next year. If the trees fruited but you got much more than the ideal growth reduce the rate by one third next year. Increase the rate if tree vigor was too low.

Now you may be getting the idea why it's so hard to get a straight answer from a tree fruit expert. Managing vigor is the key. Heavy pruning invigorates trees. So reduce the amount of fertilizer following heavy pruning.

Trees grown on sandy soils generally require more fertilizer than on loamy or clay soils. If you get a late freeze that reduces or wipes out the crop, you will have a vigorous tree to deal with.

The Burke County Extension Office has many free publications on fruit production in the home garden. Feel free to stop by and pick up copies that you need.