Citrus trees are beneficial for gardeners--not only for the delicious harvest, but also for the shade, fragrance and splashes of color they provide. In order to produce top quality citrus fruit, these trees must be fertilized often and heavily with high levels of nitrogen. The most ideal time to fertilize citrus trees in frost free areas is in January, to encourage February blossoming. In areas where frost may occur until March, fertilize the trees after the last frost. Feed one- to two-year old trees every month, and older trees quarterly. Some natural fertilizers for citrus trees include well rotted manure, fish emulsion and blood meal. Remember to always wear gloves when applying fertilizers to citrus trees.
Manure not only refers to the fertile excrement that comes from animals after they eat plant matter, but also an addition of other materials mixed with the excrement. Mix manure with 3 to 1 parts of manure and a material such as straw or sawdust. This natural fertilizer benefits young and old citrus trees, but particularly young trees because it encourages foliage growth and encourages early fruit production.
To fertilize citrus trees, use a well rotted manure, which is manure that has decomposed to the point where it is thick, crumbly and almost sweet-smelling. Allowing the manure to decompose for more than a year is what makes it well rotted, which helps prevent any potential weed growth. Well rotted manure is usually applied at the time the citrus tree is planted, and applied in the fall or spring. To apply, spread the manure in a 3-foot diameter circle around the trunk of the citrus tree. As the tree matures more, the circle should expand to match the root system area. Make sure the manure doesn't touch the trunk directly, or it may damage it.
As one of the most prized single natural fertilizers available, blood meal, also called dried blood, is known for containing a quickly soluble form of every element that is needed for quality plant growth. Gardeners who take pride in their organic gardening usually choose blood meal. Use a blood meal fertilizer that is at least nine percent nitrogen. Blood meal also contains phosphorus, potassium and magnesium among other elements. Apply blood meal around the base of the tree without touching the roots, incorporate it into the soil, then water thoroughly.
Fertilize with blood meal heavily in spring and summer and lightly in fall and winter (the amount depends on the type of blood meal you use). When mixed with kelp meal, this boosts the nutrient content even more and supplies trace elements. Blood meal also gives foliage a dark green shiny color unlike any other natural fertilizer.
This natural fertilizer is obtained by soaking trash fish to extract their soluble nutrients, creating the fish emulsion. Trash fish are fish caught commercially that have little value and aren't sorted by species. Trash fish have less value, so they are created into items such as fish emulsion and chicken feed. After extraction, it is condensed to get out about half of the water in the mixture. Ironically, fish emulsion does not have an apparent fish odor, and its nitrogen content is about five percent. Fish emulsion provides nutritional benefits just like blood meal, and is ideal for shade-loving plants such as African violets. You can use a liquid form for trees in pots, and a granular form for trees planted in the ground. Apply this natural fertilizer each month during the growing season to citrus trees to promote optimum growth. Mix it into the soil beneath the trees canopy, following the rates on the fish emulsion instructions for your tree's size.