On average, Florida harvests roughly 200 million boxes of citrus annually, totaling 70 percent of the United States' citrus production. Even so far south, anywhere between 5 and 15 percent of annual harvests are lost to frost. In the mid-Southern states of Alabama, Georgia, Mississippi, Tennessee and the Carolinas, citrus is limited to more hardy varieties.
The oro blanca is a subspecies of the common grapefruit, Citrus paradisi, which is capable of surviving in cold temperatures as low as 20 degrees Fahrenheit. It was created by cross-breeding grapefruit with the lesser-known pummelo. Like all grapefruit, it is an evergreen growing 15 to 20 feet tall with white, four-petaled flowers that bloom in spring. It grows wild throughout much of the midsouth, ranging from zones 9 to 11. The fruit it bears has a thick rind and ripens after it reaches the size of a softball. The taste is mildly tart, less so than a lemon, with copious amounts of juice. Although propagation is possible through seeds, it's typically cultivated through grafts and cuttings.
The sweet orange, Citrus sinensis, originated in Vietnam and was transplanted to the midsouth in the late 1800s. Since then, 15 varieties have been cultivated for nuances in taste, rind thickness, flesh color, juice content and cold hardiness. Industrial cultivation is limited to Florida and Louisiana for soil and weather reasons, but specimens can be found growing wild as far north as Virginia, the Parson Brown variety in particular. All species are broad-leafed evergreens growing 20 to 30 feet tall and develop a bell-shaped overhanging reach of 15 to 20 feet in diameter. Orange blossoms are renowned for their light, sweet fragrance and form in clusters of up to six blooms. Propagation involves grafting bud cuttings onto the root systems of the hardier sour orange.
The lemon, Citrus limon, also known as the true lemon to differentiate it from the Volkmeyer lemon, first developed in India, China and Burma. It did not appear in America until Christopher Columbus introduced lemon seeds to the island of Hispaniola. The tree is an evergreen, growing in zones 9 through 11. Adults range in height from 10 to 30 feet, producing minute, white four-petaled flowers that drop away in early spring to produce fruits in early fall. The fruits are canary yellow, oval shaped and roughly 3 inches in diameter by 5 inches long. Lemons contain between 5 and 6 percent citric acid, accounting for their extremely sour taste. They are used for culinary purposes in many different cultures and have found a niche in skin care products.