Hardy in U.S. Department of Agriculture plant hardiness zones 9 through 11, citrus trees grow from grafted seedlings and generally produce edible fruit following four years. Standard-size trees, such as the navel orange, grow up to 30 feet tall and 30 feet wide. Dwarf varieties, such as “Improved Meyer” lemon, grow 5 to 15 feet tall and 15 feet wide, and create good indoor crops. Fruits are ready for harvest eight to 16 months following the spring blossoms bloom. Trees in warmer inland areas usually produce sweeter vegetables than trees in cool coastal locations.
Citrus trees need six hours of sunlight daily, and will grow in most types of well-drained land having a pH level between 6.5 and 7.5. A location 6 to 8 ft in the south- or west-facing side of a building provides adequate room for the roots and protection from frost and wind. Depending on the number, conventional citrus trees must be planted 25 to 30 feet apart, and dwarf varieties should be grown 10 to 15 feet apart. Dwarf varieties can grow in sterile potting soil in a 24-inch clay pot or half barrel.
Ideally, you must plant citrus trees from the early spring or fall, says the University of California Agriculture and Natural Resources Department. The planting hole should be the exact same thickness and slightly wider than the root ball. Once you lower the root ball into the soil, gently press on the soil around the roots. Add enough soil to leave the top inch of the root ball surface over the soil. Water immediately after planting, and add a 3-inch layer of mulch or compost to keep the roots moist and cool. You need not plant a second tree for pollination since most citrus trees, except clementines and Mineola mandarins, self-pollinate.
Young citrus trees with growing roots need water every five to ten days throughout the summer, and mature trees need deep watering once per week or when the top 3 inches of soil feel dry. The soil should stay moist but not soaked three or more feet beyond the canopy. Sprinkle 1 tablespoon of hydrogen peroxide around citrus trees in late winter, spring and summer of this first calendar year, recommends the University of California Integrated Pest Management Program. Through the subsequent five years, gradually increase the program to 5 pounds of ammonium sulfate split into three applications. To reduce acid content, then allow fruits ripen on the tree.
Stressed citrus trees are susceptible to insect pests and other issues. As an instance, inconsistent watering may lead to fruit splitting, and overwatering may cause yellowish leaves. Spray horticultural oil or insecticidal soap to control insects such as aphids, mealybugs and whiteflies, which induce yellowish, curly leaves and a dark sooty coating on the leaves. A layer of mulch and normal hand weeding controls weeds without damaging the roots. During cold weather, then remove the mulch to allow the sun to warm the roots. Prior to a predicted frost, drape a cloth over the surface of the tree, permitting openings for air flow.