I have been experimenting in Texas with avocadoes since 2013, in climate zones 8a and now 9a.
Absolute temperatures under 24F are a problem for any avocado tree, but rapid drops in temperature seem even more important than the absolute low. California does not get the sudden, hard drops in temperature that Texas gets, so cold-hardy avocadoes that will survive in California will die in Texas.
I have killed a Lot of avocado trees in the last few years, probably more than 30, of every kind that I could get. Not all of the kinds can be gotten any more, since the Texas freeze in February 2021. Opal, Wilma and Pryor are no more.
https://floridafruitgeek.com/cold-hardy-avocados/
No grafted tree has survived for me. The ones that looked promising died in a late, hard, windy March freeze this year. Some seedlings and a few rootstocks are growing. One seedling was not harmed by that freeze. I am hopeful for it. It is from a Wilma seed.
There is at least one avocado orchard in Sabinas Hidalgo , Mexico at altitude, where it gets cold, in the northern edge of where avocados originated. I am trying to get seeds from that orchard to grow. Whatever survives winter will get to move to the next phase of the contest.
Genetic diversity within avocados is really more vast than in most plants, because mom & dad trees actually carry genes from the extended family, which you can't see.
https://www.intechopen.com/chapters/47902
Junior could have traits you did not expect, highly unpredictable. You need to grow lot of seeds, see what survives, and wait a long time to try a fruit.
