Members of the citrus family, orange trees come in many varieties, but all produce a fragrant white flower in the spring that gives way to fruit, which ripens the following fall or winter. The orange blossom is the state flower of Florida. Orange trees have leathery leaves and may have thorny branches. They may grow to 30 feet tall. In the U.S., orange trees are predominantly grown in the southeast and in California.
Food and Water
Orange trees require moist soil year-round, particularly during the growing season. These trees cannot tolerate standing water but should be watered regularly. The best soil for an orange tree is heavy with nitrogen, which may be applied directly or through a time-release fertilizer. According to the 1997 Sunset National Garden Book, add two ounces of nitrogen to the soil in the first year and then increase steadily by four ounces for the next four years. Beginning with the fifth year, 1 1/2 pounds of nitrogen should be used annually.
Oranges are most hardy in warm, even humid conditions, particularly in Florida and the valleys in California. Sweeter oranges require heat to form sugars, while more sour varieties require less heat. Grapefruits, according to the 1997 Sunset National Garden Book, need the most heat, and lemons need significantly less. Oranges are not frost tolerant.
Where to Plant
Plant orange trees in well-drained soil in full sun. A poorly draining area may be modified by adding a one-foot layer or mound of soil and planting the tree above the natural soil line. If the soil is sandy, add a one-foot layer of organic material, such as compost, to help retain water.
Orange trees need little pruning or branch maintenance, according to the 1997 Sunset National Garden Book and RusticGirls.com. Commercial orange growers encourage low-hanging branches, as the best fruit is usually at the bottom of the tree. Pruning should be done to remove twiggy growth and dead wood, and can be done to shape the tree.
Kinds of Oranges
Fruit oranges are available as sweet, sour or mandarin varieties, and each offers a distinctly different taste. As examples, the Valencia, which accounts for 50 percent of the late-season crop, according to thinkquest.org, is a sweet variety; the Seville, which is used for marmalades, is a sour variety; and the clementines and Satsumas, both small, sweet fruits with seeds and thin skins, are mandarin varieties.