Q: When is the best time to prune and fertilize citrus?
A: There is no reason to prune citrus unless to shape it to keep it small for a confined area — otherwise don’t prune. Sometimes citrus will drop all their leaves. Don’t panic and prune — wait they will come back and leaf up in the spring and sometimes to a lesser extent in the fall.
The best times to transplant citrus is March–April, and September–October. But all other months are fine with extra care. You may transplant citrus trees that have fruit on them because their roots were used to the confined area. After transplanting, the roots need time to get accustomed and adapted to their new home. Often they will not throw fruit again for three to five years.
If your citrus trees have yellowish leaves, it’s likely due to wet soil, too much watering, a lack of a nitrogen fertilizer or another nutrient deficiency, which is the result of an alkaline soil.
Fertilize in February, May, and September or October — just remember Valentine’s Day, Memorial Day and Labor Day. Do it in three steps:
1. Water the trees for a couple of hours.
2. Sprinkle on the soil a complete citrus fertilizer (like 16-8-8 or any other complete fertilizer with all three numbers in the ratio) at about the rate as you would sprinkle pepper on your food.
3. Water again for several more hours.
If you have citrus in the same location longer than five years, use fertilizer 21-0-0, ammonium sulfate. Trees younger than five years need phosphate, the second number in the ratio for new root development. Trees older than five years are considered established and the roots only need nitrogen, the first number in the ratio.
On trees younger than five years, sprinkle it under the complete spread of the leaf canopy. On trees older than five years, sprinkle it on the soil under the outer two-thirds of the canopy and 25 percent beyond the drip line.
During January water deeply about once a month. During the hot months of June-September water every seven to 10 days and for the other months adjust for the temperature.
Drip irrigation systems may be inadequate for citrus irrigations unless they are used on young trees, have a lot of drippers and you leave them on for many hours. Drip irrigation systems are great when used on flowers, shrubs and desert trees.