Navel orange trees (Citrus sinensis) produce sweet, easily peeled, segmented fruit which makes them ideal for consuming. The tree grows approximately 30 feet in height with a rounded 20-foot spread. Numerous navel orange cultivars also have stems that are quite thorny. Fragrant blossoms are produced in large 6-inch clusters each spring. The tree bears fruit in fall and winter, and numerous cultivars are available.
Navel orange trees require subtropical or tropical weather conditions to thrive. Many navel cultivars can withstand temperatures that dip to 20 degrees F, but the fruit will be severely damaged during extended exposure and blossoms will perish. A few cultivars require protection if the weather drops below 24 degrees F. Despite the navel orange tree's hardiness in cold temperatures, even a quick frost can kill the fruit or blossoms for the season.
If a heavy frost is expected, it is imperative to keep the air flowing around the orange tree to protect its crop. Many gardeners place fans beside their orange trees to keep the frost from forming on the delicate fruit. Covering the tree with blankets offers moderate protection. Water is also utilized to protect the trees through overhead irrigation.
Navel orange trees are highly tolerant of drought, but fruit productions will be seriously handicapped if enough water is not received. The tree requires between 40 to 45 inches of rain per season according to Floridata. Orange trees require well-draining soil. The trees do not do well in standing water.
Plant navel orange trees in full sun to partial shade. The trees will produce more abundant fruit in a full-sunlight location. Orange trees do not do well in heavy soil conditions. Mix organic matter such as peat moss, aged manure or bark chips into the soil prior to planting the orange tree. Plant orange trees beside the south-facing wall of a house, building or fence line to offer wintertime protection. Always maintain at least 12 feet between the tree and the structure.
Fertilize the orange tree four times a year using 1 cup of ammonium sulfate (21-0-0) when the tree is less then a year old. Increase the amount to 2 cups per application when the tree is two years old or older. Water the fertilizer into the soil completely once applied.
Pick oranges when they are completely ripe on the tree. Once oranges are picked, they will cease to ripen or sweeten further.