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Citrus Fertilization

Minor nutrient deficiency on citrus. Photo: Dr. W. Nishijima

Photo: Dr. Wayne Nishijima
Citrus leaves with minor nutrient deficiency

Question

How often should I fertilize my citrus tree and with what?

Information

Advice varies on this. It is difficult to give broad recommendations on how to fertilize citrus trees (or any crop) because soil conditions vary so widely. We recommend that you start with a soil analysis so that you know what you have in your soil to begin with. Only then will you know what to add and how often.

For the home gardener, citrus trees in the lawn may get all the nutrients they need from the same fertilizer used on the surrounding lawn. For young trees in the first few years of growth, apply rapid-release fertilizer frequently according to the age of the tree: every two months in the first year, every two and a half months in the second year, and every three months from the third year on.

Use 16-16-16, 8-8-8, or 10-20-20 spreading fertilizer over the root zone from 6 inches away from the trunk to just beyond the drip line. Water thoroughly.

In general, proper fertilization depends on the amount of nutrients applied rather than the amount of fertilizer. Specifically, Phosphorus (P) is needed for growth of new roots when you first plant, and for establishment of flowers in mature trees. Nitrogen (N) is needed at all times, but especially for new growth.  Nitrogen and Potassium (K) are necessary for healthy fruit development.

I think that, as with all gardening, you need to look at the plants in your yard. If they look healthy and are producing, leave them alone, keep doing what you’ve been doing, or cut back slightly on the fertilizer. If the leaves look chlorotic (yellow) the tree will benefit from an application of micronutrients.

Kendal Lyon, Hawaii Island Master Gardeners