Tucson, Arizona provides a good climate to grow orange trees. The temperature almost never drops below 32 degrees F. The average minimum temperature in December and January is 39 degrees F, warm enough for an orange tree to survive without protection from the cold. And although summer temperatures of 100 degrees F are common in June and July, they will not harm a mature orange tree. But you will need to water your orange tree: Tucson receives only about 12 inches of rain a year.
Conduct a soil test. Orange trees need an acidic soil with a 6.0 to 6.5 pH. If your soil test reveals a higher, more alkaline number, add sulfur when you prepare the planting hole. If your soil is sandy, add 1.2 ounces of sulfur for every square yard of garden space. For clay to loam soils, add 4.6 ounces of sulfur for every square yard.
Dig a hole in an area with well-drained soil that receives morning sun or filtered sun all day. More sunlight could result in sunburn on hot Arizona days. For a tree in a 2-gallon nursery pot, dig a hole twice the size of the rootball and mix 1 gallon of compost with the existing soil. Place the tree in the hole and fill it with the amended soil.
Water the new tree well after you plant it, but be careful not to allow it to stand in a puddle of water---this can cause root rot and kill your tree.
Hang shade cloth over a young tree during its first summer to protect it from sunburn. String shade cloth from nearby trees or bushes or build a simple frame with plant stakes, PVC pipe or small wooden boards.
Paint the trunk of your tree with white tree paint to protect it from the sun.
Fertilize your orange tree after its first year in the ground with a fertilizer designed for citrus trees. Fertilize in March, May and September.