About 10 years ago we started investigating what avocados would grow in our Northern California Sierra Foothill location. We are at 1000 feet, and do experience an occasional frost, as well as very hot weather in the summer. Avocados are grown in California, but the varieties you see in the stores, such as Hass and Bacon, are typically grown in mild southern California coastal climates. However, after research we determined that Mexicola hybrids (Mexicola, Mexicola Grande and Mexicola/Stewart) and Pinkerton were some of the best to try in our area so we planted a small orchard of these. The Mexicola types have all gotten mixed up, we are not sure which tree is which now, but they all provide similar fruit.
Our Mexicola hybrid trees have gotten very tall, some of them over 20 feet tall now, and set a crop in the Spring that ripens over the summer and is ready to harvest in the fall. We have found that the trees like a lot of water, and they also are heavy feeders so they receive a lot of compost and organic fertilizer. The fruit does not store well on the trees once the tops start blackening, as the thin skin has a tendency to crack around the neck. We just wash the fruit, peel it and eat it anyway but try to harvest the fruit before it develops these cracks.
This year our crop finally is abundant enough that we are actually able to sell our Mexicola avocados. These avocados have a very thin skin (you can actually eat the skin). They ripen from the neck down, so at first they will be green, then the neck will blacken and soften, and finally they will blacken and soften and the skin will slightly wrinkle. Then they are ready to eat!