Avocados are native to southern Mexico and grow best in subtropical zones. They prefer a semi-humid climate with warm weather. The most cold-hardy varieties can withstand temperatures of about 25 degrees F. Avocados are grown commercially in the Rio Grande Valley area of Texas and some varieties do well in central Texas. The northern Texas climate is too cold for outdoor growing of avocado trees.
Cold Tolerance of Avocados
Mexican avocado strains are the most cold tolerant, generally withstanding temperatures to 25 degrees F. The Mexicola variety is the most cold-hardy variety. It loses its leaves at 20 degrees F and the trunk dies at 17 degrees F. The avocado trees that do best in Texas are Mexican varieties grafted onto West Indian rootstock. The West Indian varieties have high salt tolerance and good disease resistance.
During the first two years, avocado trees are very tender and susceptible to cold weather. Texas avocados need extra care during this time. When a freeze is expected, mound garden soil around the trunk for additional protection. Water the tree thoroughly and cover it with a blanket or quilt. During severe freezes, add a string of lights or a small heater under the covers. Mature trees are more cold resistant and do not need this extra protection.
Because of their susceptibility to cold, plant avocados in the warmest location in the residential landscape, usually the south or southeast side of the house. Allow plenty of clearance, at least 8 to 10 feet away from the house. Avocado trees grow quite large. Avocado trees will grow in most soils found in southern Texas. The most important factor is good drainage. In areas with poor drainage, create a mound of soil and plant the tree on the mound.
Urban Harvest, a Houston charitable organization that supports a network of urban gardens, recommends a number of avocado varieties suitable for growing in south and central Texas. Opal, Wilma and Fantastic avocado are large, cold-hardy Mexican varieties with good flavor and color. Joey and Poncho avocados produce medium-sized fruit with good flavor. Texas A&M AgriLife Extension also recommends Opal, Wilma and Pryor.
In the Rio Grande Valley, Lulu is grown commercially. Lulu is cold-hardy to 27 degrees F and tolerant of the soil salinity common in south Texas.