Orange trees are grown commercially in warmer areas of the United States, primarily Florida and California, but they also make attractive specimen trees for homeowners gardening in zones 9 to 11. Besides the obvious attraction of its delicious fruit, the orange tree produces highly fragrant flowers and its glossy evergreen foliage is pleasing on its own merit.
The orange tree, Citrus sinensis, is compact with a round, symmetrical crown and reaches 20 to 30 feet high. Its shiny, leathery leaves are up to 4 inches long and oblong in shape. The tree's spring blooms become oranges in autumn or winter, depending on variety. It's not unusual to see new blossoms appear on the tree simultaneously as last season's fruit, says Floridata, an online encyclopedia of landscape plants.
The most commonly grown oranges in Florida are "Hamlin," "Pineapple" and "Valencia;" the two main California varieties are "Washington Naval" and "Valencia." "Hamlin" is early, high-yielding and cold-hardy, with a small, smooth, seedless fruit. Neither the fruit nor the orange is highly colored, but it is very juicy. "Pineapple" is Florida's leading mid-season (December through February) producer; it has a pineapple scent and good color, with a medium amount of seeds. "Valencia" is a thin-skinned juice orange ripening from March through July. "Washington Navel" has a thick, easily-removed rind and is seedless and flavorful, making it excellent for eating out of hand. In California, it ripens at the December holiday season.
Although the orange tree no longer exists in a wild state, it is believed to have originated in southern China and northeastern India. Carried back to the Mediterranean by European traders, the tree became a popular subject for greenhouses called orangeries. After being introduced to the New World by the Spanish and French, orange orchards were established in California and Florida. Oranges are now the most commonly cultivated fruit in the world, according to Purdue University. The United States leads the world in this fruit's production with Florida by itself producing 200 million boxes of oranges each year. Oranges are also commercially cultivated in California, Texas and Arizona, and to a much lesser degree, Louisiana, Mississippi, Alabama and Georgia.
Even if it did not produce fruit, the orange tree would be treasured for the beauty and sweet scent of the orange blossom, adopted by Florida as its state flower. The delicate white blooms have long been used in bridal bouquets, and the flower's essence serves as a perfume ingredient. Orange blossom honey, produced by the honeybees pollinating the flowers, is prized for its sweet orange flavoring.
Orange trees will tolerate light shade but require full sun for maximum fruit production. While they withstand dry conditions, they bear better fruit if they are kept watered during dry periods. Because orange trees are sensitive to cold temperatures, growers (particularly those in the northern end of the tree's zone) may need to take measures to protect the tree from cold and frost. These include planting the more cold-sensitive varieties on the south sides of buildings, and preventing frost from destroying blossoms by covering the tree with a blanket or plastic sheeting or using fans to circulate air around the tree.