Answer: Your sandy soil is just fine for fruit trees. They appreciate fast-draining soils, but they're likely to need more frequent deep watering than the same trees in a loamy or clayey soil. It is generally not necessary to fertilize fruit trees. Check tree growth to determine whether fruit trees need fertilization. Nonbearing fruit trees should grow approximately 15 to 30 inches per year. Bearing trees should produce 8 to 15 inches of new growth. (The actual amount of new growth will vary due to differences in varietal vigor.) Fruit trees making less than desirable growth may need fertilization. Apply a balanced fertilizer, such as a 10-10-10, in early spring before bud break. The recommended rate is 1/10 pound of actual nitrogen per year of tree age. (Tree age is the number of years since the tree was planted in the home garden.)
For example, a 5-year-old tree should receive 5/10 or 1/2 pound of nitrogen. Uniformly broadcast 5 pounds of the 10-10-10 fertilizer (10 percent of 5 is 1/2 pound of N) in a circular band about 2 to 3 feet from the trunk and extend out slightly beyond the dripline of the tree. One pound of actual nitrogen is the maximum for fruit trees 10 years of age and older.
You didn't say exactly which fruit trees you're growing (apple, pear, plum, etc.) so I can't really tell you when to prune. If you prune at the wrong time of the year, you could accidentally prune off the fruiting spurs or flower buds. If you submit another question through the Home Depot website and tell us exactly which fruit trees you're growing, we can guide you through pruning to maintain health and encourage a large harvest.
Best wishes with your trees.
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