What you need to know about Southern California avocado trees

Q. The house I rent has a mature avocado tree in the yard that produces big beautiful avocados that never seem to ripen. I’ve tried putting them in a brown paper bag and they turn dark but are hard as a rock. Any suggestions?

There are different types of avocados that will grow and produce in Southern California, and each type will ripen at a different time. The trick is to figure out what type of avocado tree you have.

Mexican avocados, such as Bacon, Duke, and Mexicola, are somewhat cold-hardy and will tolerate hot, dry summers. If you live in the Inland valleys, these trees are more likely to survive if planted in an area that’s protected from cold and wind. In California, they bloom from fall through spring and the fruit is ready to harvest six months after that. The fruit can be pear-shaped or round and has thin, dark green skin. When crushed, the leaves release an anise or licorice scent.

Guatemalan avocados, such as Gem, bloom later than Mexican varieties and the fruit is ready to harvest up to 18 months after that. The leaves are red-tinted when new, and they lack the anise scent that Mexican avocados have. The fruit tends to be rounder rather than pear-shaped and has thick, bumpy skin that can be either green or black (but usually lighter than the typical Mexican avocado).

Just to make things more confusing, many of the more popular varieties are hybrids of Mexican and Guatemalan avocados. (I’m not even going to mention West Indian avocados, since they are horrible). Here are brief descriptions of some of the most popular hybrids – see if your tree fits any of these.

Fuerte was the most popular variety before Hass came along. It blooms February through April, has very good fruit quality, and is relatively cold hardy. The skin is thin and leathery and green when it ripens November through March.

Hass is currently the most popular cultivar and is somewhat intolerant of cold, making it less suitable for the chillier Inland areas. Its skin is black and bumpy at maturity and is medium thickness. It tastes even better than Fuerte.

Lamb Hass is similar to Hass but is more tolerant of high heat and wind and is less susceptible to persea mites. The tree is smaller than Hass, making it more suitable for backyard growers.

Avocados are not edible straight from the tree. The ripening process begins when the stem is cut, so mature fruit can remain on the tree for some time without spoiling. Since most cultivars have such a long ripening period, it can be difficult to figure out when it’s time to pick. To make matters more complicated, fruit can mature at different times based on other factors such as elevation, latitude, microclimates, and location. If you can narrow down the ripening period, I recommend picking a fruit every week and letting it ripen on the counter. This process may take some fine-tuning but is the simplest way to figure out when to start picking.

Los Angeles County

mglosangeleshelpline@ucdavis.edu; 626-586-1988; http://celosangeles.ucanr.edu/UC_Master_Gardener_Program/

Orange County

ucceocmghotline@ucanr.edu; http://mgorange.ucanr.edu/

Riverside County

anrmgriverside@ucanr.edu; https://ucanr.edu/sites/RiversideMG/

San Bernardino County

mgsanbern@ucanr.edu; 909-387-2182; http://mgsb.ucanr.edu