When to Feed Citrus Trees

Fertilizer not only helps citrus trees produce quality fruit, but can also increase fruit quantity and help keep the trees vigorous and problem-free. Exact amounts and formulas vary slightly depending upon what type of citrus you grow, climate and soil conditions, but citrus needs to be fed regularly during the growth cycle. Both granular fertilizer and liquid spray fertilizer may be used to feed citrus plants.

Fertilize citrus trees beginning in late January. Use 1 lb. of complete fertilizer such as 8-8-8 or 6-12-6 for every year of the tree’s age. During the first year, begin at least a foot away from the trunk and apply granular fertilizer in a circle. Use 1 lb. of fertilizer, spreading it in a 30-inch circle. After the first year, fertilize outward from the tree’s drip line, or canopy edge. This is where the feeder roots are located. Fertilize three times during the growing season. An easy-to-remember schedule is Valentine’s Day, Memorial Day and Memorial Day. Nitrogen is important for citrus trees. Make sure the fertilizer you use provides at least 1/8 lb. of actual nitrogen the first year, ? lb. the second year, ? lb. the third year, and 1 lb. every year thereafter. After age 5, grapefruit trees need half as much fertilizer as other citrus trees.

Apply a slow-release granular fertilizer annually, in March, if the trees are kept in a container outdoors. Stop fertilizing in winter so the trees will go dormant, and begin again in spring to encourage new growth. Make sure the fertilizer does not touch the tree's trunk. Do not add fertilizer to the soil when transplanting potted citrus from one container to another.

If you start citrus trees indoors from seed, wait until the seedlings have several sets of leaves before applying fertilizer. Whether grown from seed or purchased as young plants, use a diluted potassium fertilizer when the seedlings are old enough. Repeat every two weeks until the seedlings are ready to transplant. Liquid fertilizer is convenient and comes ready to apply. Follow package instructions on all fertilizers.

In a pinch, use ordinary grass or shrub fertilizer to feed your citrus trees. Since these formulas usually do not include other nutrients citrus needs, follow up as soon as possible with a foliar spray that contains magnesium, zinc, boron, manganese and copper. Stop fertilizing outdoor citrus trees at the end of the summer, to help the trees go dormant. Fertilizing too late can cause new growth that won't have time to become acclimated by winter.