Orange and other citrus trees are hardy in USDA zones 9 to 10 and, in general, do not grow well in the ground in colder climates. There are some varieties that can withstand temperatures down to 10 degrees. In addition, dwarf varieties may be planted in large containers and cared for indoors or on sun porches through the winter. If you choose to grow citrus in a colder climate, be aware you will need to keep the plants warm and imitate their winter climates. These plants should be potted in extremely large containers, and in the winter, should get about eight hours of sun per day, should be deeply watered several times a week and may be fertilized with a high-nitrogen fertilizer.
Moro Blood Orange
These trees are smaller than more mainstream orange trees and the oranges themselves have red-colored flesh that have a hint of berry taste. Moro blood oranges got their origins in Sicily and are hardy to about 27 degrees.
The satsuma mandarin oranges are smaller than standard navel oranges and resemble tangerines. The trees are a little smaller than navel orange trees, and many will withstand temperatures down to 12 degrees as well as drought conditions. The fact that some satsumas, including Kimbroughs, Owaris and Mr. Macs, could withstand such cold temperatures was discovered in the early 1900s in New Orleans, when these were the only types of satsumas to survive a killer freeze.
Ten Degree Tangerines
These fruit trees are named for their hardiness and were developed in Texas, where the nights are colder than more traditional orange-growing areas. These thorny trees, which produce a fairly tart fruit, are believed to have mandarin and Yuzu as ancestors.
The Yuzu citrus tree is popular in the mountains of Japan and can survive temperatures down to the low teens. The tree produces a fruit that is cross between lemon, lime and grapefruit. Though not a popular eating fruit, the Yuzu may be used in cooking.