Growing citrus trees is one of the benefits of living in a year-round warm weather climate. Citrus trees need special care, however, and must be protected from drops in temperature and a number of pests and diseases. Growing citrus trees organically can offer unique challenges, as they require heavy doses of nitrogen during growing season. Micronutrients like magnesium, boron, copper and zinc are especially important for fruit production.
Commercial Organic Fertilizers
There are a number of organic fertilizers on the market that provide sufficient nutrients for citrus trees. These fertilizers use processed natural ingredients that are high in nitrogen and contain the trace micronutrients like boron and magnesium that help the tree to produce healthy fruit. Several granular products are available that can be leached into the soil with water to provide nutrition throughout the growing season. Liquid organic products are also available.
Natural Organic Fertlizers
Compost and manure are two natural organic fertilizers that may be used on citrus trees. Compost conditions the soil and adds nutrients, but must be applied more frequently than other organic fertilizers. Manure products are often used for citrus, but care should be taken to avoid contact with roots, which could cause burning. One organic grower uses a combination of fish emulsion, dried seaweed powder and a dash of ocean water to fertilize citrus trees.
Fish emulsion is often a recommended organic fertilizer for citrus trees, though it can be expensive. It is, however, a good fertilizer to put on citrus trees during cool weather when slow-release fertilizers become ineffective. It offers a rich supply of nutrients that are immediately available to the tree. It has an odor that dissipates quickly after application. Fish emulsion requires more frequent application than chemical fertilizers.
Composted chicken manure can also be used as a good organic fertilizer for citrus trees. Chicken manure contains from 2 to 3 percent nitrogen, which citrus feed on heavily. By comparison, cow manure only contains 1 percent nitrogen, according to the University of Florida Extension. Chicken manure should be applied frequently but thinly, taking care not to get the material on leaves, which may cause burning.
Soybean meal is not as well known as other organic fertilizers but is often recommended for citrus trees. It is very high in the nitrogen that citrus trees require and also has available phosphorus. It is one of the more expensive organic fertilizers, however, so gardeners should inquire at animal feed supply stores to get the best price. It is usually applied at 4 lbs. per 100 square feet.