Citrus trees need the warm climate of Florida, California, and portions of Texas, Arizona, and the Gulf coastal strip to ripen the fruit properly. Even in those areas, it is often necessary in winter to bank soil around the trunks or to wrap the trunks with insulating material such as layers of newspaper. Sour orange (Citrus aurantium) and mandarin orange (Citrus reticulata), the most hardy, can survive temperatures of 24°F Citrus trees do best in well-drained loam and in full sun.
Buy budded stock from a local nursery to ensure its hardiness and to avoid varieties locally subject to disease. Plant trees during their winter dormancy, usually February.
Planting citrus trees
A common mistake is planting the trees too close. A grapefruit tree, which may grow 50 feet tall, needs a clear radius of at least 15 feet (30 feet between trees); an orange tree needs 12 to 15 feet; lemon, lime, and kumquat trees, 8 to 10 feet. Citrus trees can be planted close for a hedge but then they require frequent pruning.
Dig the planting holes large enough so that the roots can be spread fully. Add peat moss and citrus fertilizer to the fill-in soil. Plant trees at their former growing depth or slightly higher, water deeply, and thin and cut back branches.
Keep the ground beneath a tree’s canopy heavily mulched. Apply a high-nitrogen fertilizer in spring and summer, a fertilizer without nitrogen in fall. In dry weather give trees a deep soaking weekly. Prune out suckers, dead branches, and crossing limbs. Prune grapefruit trees to keep them low. Ask your Cooperative Extension Service what pesticides to apply in your area.