Can You Grow Avocado Trees in Arizona?

You can grow avocado trees in Arizona, but it requires great care and attention. While avocado trees are adapted to desert warmth and soil types, they do not do well in the cold. As any Arizona resident knows, when the sun goes down, the air temperature drops significantly. Thus avocado trees require cold protection and maximum attention from gardeners to flourish in Arizona.

There are three types, or races, of avocado tree. These types are descended from the same parent species (Persea Americana) and are West Indian, Mexican and Guatemalan. Mexican avocados are the most cold resistant and thus the best candidate for growing in Arizona. However, Mexican trees don't tolerate salty conditions and produce fruit heavily susceptible to disease.

West Indian avocado is the least cold tolerant variety. Guatemalan avocado sits between the others in cold hardiness. The race is important as it is often interbred with West Indian and Mexican avocados to create commercial cultivars and hybrids.

Gainesville and Winter Mexican varieties of avocado sustain particularly cold temperatures but are not commonly available throughout the United States and produce low quality fruit. Online botanical resource Phoenix Tropicals reports that a Winter Mexican tree grew in the Phoenix area with few problems, tolerating temperatures ranging from 115 to 22 degrees Fahrenheit.

Avocado trees do not come from true seed. Young trees take 10 to 15 years to begin fruiting. Because of this, the most common method of avocado tree propagation is grafting. Grafting is most successfully done in cold months.

However, Texas A&M University horticulturalist Julian W. Sauls points out that cold-hardy avocado varieties are not readily available in most locations. The best trees for growth in Arizona are transplants or those grown in nurseries or greenhouses and replanted. Staking newly transplanted trees is important for support.

Avocado trees flourish in well-aerated soil with a pH level of 6 to 6.5. Trees should be mulched with coarse material (redwood bark or other woody mulch) at a rate of 1/3 cubic yard per tree in a ring spaced 6 to 8 inches from the trunk. When growing multiple avocado trees, plant them 5 to 25 feet from each other and other large trees. Eliminate competition from weeds and grass by planting trees in regions without either. Watering should be done slowly and thoroughly. Runoff water will be of no benefit to avocado trees, but soggy soil is also harmful.

The California Avocado commission recommends using a standard nitrogen, phosphorus and potassium fertilizer amended with zinc at a rate of 1 to 2 tsp. per tree, per year.

Protecting Arizona avocado specimens from the cold is essential. The two best methods of cold protection are deep planting and surrounding the trunk in a soil mound. This will protect the roots and base of the tree so that even if the top dies in a severe frost, the specimen will survive and grow again.

In the event of a predicted frost, tent trees for protection. This entails covering the tree in a blanket or tarp, with the corners tuned up and staked to the ground. Placing heat lamps or other such devices within the tent also helps. Water trees two to three days before tenting and build up the earthen mound around the trunk for maximum protection.