Q: I love Hass avocados. Can we grow them in the low desert, and if so, how do I do it?
A: There are about 500 varieties of avocados. Of these there are three main types of avocado — Guatemalan, Mexican, and West Indian — and of these there are multiple hybrids, with Mexican and Guatemalan and their hybrids being the best adapted to desert winters. Seven varieties are grown commercially in California, and the Hass variety accounts for approximately 95 percent of that total crop.
Mexican varieties are the hardiest — which means cold-tolerant — and bear fruit with smoother, thinner shiny green skin. Guatemalan avocados need frost-free climates and can be identified by their blackish, green, thick, bumpy rinds — Hass being a Guatemalan variety. West Indian fruit are the most frost-sensitive and are identified by thin, smooth, greenish-yellow skin.
Hass avocados are a Guatemalan type which is very sensitive to temperatures below 30 degrees. Mexican types with a smooth greenish yellow skin are more suited to your climate. That is not saying that Hass avocados won’t grow here, but they will need to be protected from freezing temperatures.
There are challenges to growing sub-tropical fruits in non-native locations. Though it is rare to see avocado producing trees in our extreme desert climate, it doesn’t mean you can’t have a fruit-producing avocado tree in your backyard if you choose.
It just comes down to how much you are willing to baby-sit it in order to have your own homegrown avocados. I have personally seen three producing avocado trees in southeast Mesa. My brother has one of them.
The low desert has the climate extremes of hot summer and cold winters, not the mild and humid climate of the tropics and California coastal areas. Avocado trees enjoy full sun but need protection from the hot western sun during the first few years until they develop a strong root structure and dense foliage to protect the sensitive bark.
The trunks need to be protected just like newly planted citrus trees. I recommend painting any exposed bark with diluted water-based paint, or planting the tree on the east side of your house so it only receives morning sun and afternoon shade. You can also get a natural brown paint from nurseries. An 8-foot shade structure for avocados with openings that the plant can eventually grow through would also be beneficial.
Avocado trees can grow to be very tall trees and eventually be too tall to cover, so protection and shading is only temporary.
Avocados need well-drained soil — they can’t tolerate wet feet, including wintertime when the ground stays moist longer. This doesn’t mean that avocado trees are drought tolerant, they need regular deep irrigations.
Remember, the length of the irrigation remains constant year-round, but the interval between irrigations changes according to the season. The water needs to penetrate down to 3 feet. That is where the roots should be. You will determine that depth by pushing a T-handle probe into the ground the day after irrigation. When the probe stops, you have hit hard, dry ground.
During the hot weather of summer you will water every three to five days, depending on your soil density. During the cold days of November through January, about every three weeks will do.
Avocados are very sensitive to salt burn, and there is a lot of salt in our water combined with heavy clay soil. It is important to remember to water slow and deep.
Avocado trees grown from seed may take from 10 to 20 years to bear fruit, and then you won’t know what variety it is, and even after all that waiting it is questionable whether it will produce fruit at all. They won’t grow true from seed because avocados, like almost all the other fruit we eat, are the product of grafting and cross-pollinating.
Since the process of grafting involves mixing the tissues of the seedling with those of a producing tree, it is often just easier to simply buy a grafted tree from a reputable nursery. Avocado grafting requires precise weather conditions and therefore a successful graft yield is often low — even for professionals.
If you are still determined to grow an avocado tree or other tropical plants contact Tropica Mango Nursery, 3015 E. Baseline Road, Phoenix, at (602) 576-6948.
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