Fertilizing an orange tree ensures that it grows into a healthy, mature specimen with solid fruit production. Food increases the fruit yield, makes the foliage healthier and helps the orange tree stand up to disease and pest infestation. Fertilizer replaces nutrients that may be lost from the soil, which could cause the orange tree to die. It's especially important to feed an orange tree when it's newly planted and struggling to become established.
Rake mulch away from the base of the orange tree. Push it outside the drip line, which is the line where the canopy of leaves ends. Fertilizer needs to be directly applied to the soil for the best results.
Choose a slow-release commercial fertilizer for extended benefits. Pick one with a nitrogen-phosphorus-potassium ratio of 4-6-8 or a 12-4-8. It should also contain micronutrients like magnesium and calcium.
Consider a liquid citrus fertilizer if you prefer. This kind is also ideal for orange trees that are grown in containers. Liquid food should be applied to trees every three months beginning in the early spring with blooming.
Feed an orange tree that was recently planted in the ground every six weeks between February and October. In their first year, apply 1/2 cup of food the first time and slowly increase the amount until you apply 1-1/2 pints by September.
Pour liquid fertilizers around the base of the tree, over where the roots grow. Follow the manufacturer's guidelines when you use powdered fertilizers.
Work the food into the soil surface by raking it gently. The goal is to get it mixed in with the top 1 to 2 inches of soil.
Water the orange tree thoroughly. This will help the fertilizer work its way down to the roots.
Put the removed mulch back around the base of the orange tree. Make sure there is a 2 to 3 inch thick layer spread out to the dripline. Keep the mulch 2 inches from the tree trunk, however.