Answer: There is not a rule for how often you fertilize oranges. Many gardeners fertilize once or twice a year, but there is nothing wrong with feeding them monthly from March through August. The key is how much. If you fertilize more often, break the total amount down into smaller doses.
A soil test is the best way to determine your plant's nutritional needs. In the absence of that information you may go with about 1/2 pound of a balanced fertilizer per inch of trunk diameter, spread out evenly beneath the branches. This could be applied in March, May and July.
Compost is another great way to feed plants. Spread a couple of inches beneath the trees in spring each year.
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