[header] How to fertilize fruit trees [title] Perform a soil test. [step] Before you attempt to fertilize a fruit tree, make sure the tree actually needs fertilizer. Fertilizing unnecessarily can cause poor plant growth, so have a soil test performed to see if your trees need fertilizing. 
[substeps] To do a soil test, you would take a small sample of soil from the base of your tree. From there, you can take your soil to the state's agricultural department and get a test done from somewhere between $0 to $30.