You want the best fruit your fruit tree can give, right? Good fruit comes from fertile soil, so the key is to maintain soil health. Sometimes, this means adding fertilizer, but know how to prevent over-fertilizing. Fertilizer in excess can be more damaging than no fertilizer at all.
The most practical way of checking soil fertility is by investigating the annual growth of the tree. If you inspect the branches and follow the branch from the tip to the previous year’s growth, you can measure how much the fruiting tree grew in a season. New growth is flexible and green, while last year's growth is darker (often brown) and more rigid. A mature, fruit-producing tree should have 6-8 inches of vegetative growth each year. Immature fruit trees grow more quickly, but don’t produce fruit.
Soil is “fertile” if it has the right balance of nutrients to support healthy growth. These nutrients include nitrogen, potassium, and phosphates. You can find pre-mixed fertilizers at your garden store that include all of these. For fruit trees, you want a fertilizer packed with phosphates to promote healthy fruit and flower development.
A common mistake with home gardeners is to use too much nitrogen, or the wrong type of nitrogen compound. Nitrogen additives affect the pH of the soil. If your soil pH is above 7.0, that means it’s “basic,” and you should use an ammonium-based fertilizer for nitrogen. If you find that your soil pH is below 7.0, that means it’s “acidic” and you should use a nitrate solution for nitrogen. To learn more about pH and how to test your soil, ask a local horticulturist or agriculture extension agency.
A suggested rate of fertilizer to use for each fruit tree is one pound of fertilizer for every inch in trunk diameter. BUT be sure to read the directions on the fertilizer packaging. Some fertilizers are packaged more concentrated than others. Fertilization should be done directly before bloom. For most trees, this is around March. Be sure to know the flowering time of each specific tree, though. If you purchase your tree from Nature Hills, you can figure this out with a quick look at the product page.
Don't let all this talk of numbers and pH and nutrients scare you out of buying a fruit tree. Fertilization is much simpler than it sounds.
1. Don’t over do it!
2. Phosphates are your friends!
3. Pay attention to pH!
4. Read the directions!