The proper term is probably cultivar. But you can call the Botany police if you want.
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I’ve never read about cultivars at the UCR site that are hardy in zone 8b. I have met with breeders who are trying other species.
Then tell us all about your knowledge of these species Richard …
The best part about knowing everything is getting to share it.
I am very interested to hear what other species breeders have been experimenting with and what they have found. Even if the fruit doesn’t taste as good as P. americana, I think many people would love to grow them.
Is it not possible to keep avacados small and wrap them like a fig and use lights if temps warrant?
Yes it is possible.
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I know someone who simply uses heat lamps pointed up at the tree from the ground. They are set up on a thermostat to turn on at 40F. It’s not very energy efficient, but he doesn’t have to go through the effort of covering them, which can be a pain!
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You could start by attending conferences that these breeders frequent.
we got a mexicola from lowe’s years ago and it tolerated 15F for several hours in vegas, with no die back, and even more amazingly, not even a single leaf-drop. It is actually the dry heat and direct sun of vegas summers which kill avocados instantly.
Thanks for this! This is officially the first first-hand account I have seen of a cold-hardy avocado living up to the claims.
glad to hear my input was worth anything, and wishing you success with the ‘tough customer’ that the avocado has always been for out of zoners! 
btw there are two mexicola’s, the mexicola we grew was plain mexicola. There is also a ‘mexicola grande’ which is supposedly just as cold-tolerant and bears bigger fruits
from the research I’ve done, it seems that Mexicolas are supposed to be hardy to 15F, and Mexicola Stuarts even hardier, down to 10F or something. I’ve also read about a native AZ variety called Aravaipa thats supposed to be hardy to 10F or less and about five varieties from Texas (lila, fantastic, brazos belle, poncho and joey) all claimed to be hardy to 10F.
I don’t have any personal experience with these varieties (if anyone knows where to get the TX varieties in CA, LMK) but I did plant a Mexicola and a Stuart here at my house about two weeks ago. We’ve had some light frosts (29-31) since but the real test won’t be until next winter, as we get our 18F hard frosts in December. That said, I think the winds up here might be even more brutal on the avos than the frost. Really hoping that they become productive trees!
Actually it is a cultivar from Arizona, not a native species.
Beware of nurseries writing ad copy to lure desperate growers.
I just got a Stewart for planting also. We’ll have to compare notes
Note that Stewart and Stuart are different cultivars.
I live near Phoenix, where the Aravaipa seedling was found. My understanding was that its claim to fame was being tolerant to 120F heat and sun. The lowest temps Phoenix sees are in the low 20s, so I’m not confident how cold hardy it is below that. This certainly doesn’t mean it’s NOT cold hardy down to 10-15F, though.
The Aravaipa might be a good choice for @jujubemulberry out in Las Vegas.
Good to know! They are used interchangeably on online forums. (The same ones that had me worried it would not be very productive). Hopefully I picked the right one for Poway!
you got that right! I am still waiting for it to become a bit more mainstream. Apart from being (expectedly) in-demand, there seems to be no online nursery carrying it.
Have seen plenty of youtube videos depicting aravaipas being grown somewhat out in the open in phx, which is quite encouraging. Only caveat is that even though it is generally hotter there during summer, humidity there seems to be higher than here…which seems to be an influential factor.
Yes, Stewart is the more common, recommend for your area, and has a very good flavor. The other “Stuart” is a straight Mexicola with relatively poor flavor – at least in comparison to avocado fruits we are familiar with from stores.
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