The great Seattle cold-hardy avocado trial

Avocado rootstocks don’t control tree size much at all, they can only slightly influence vigor, but mostly the growth habit of the grafted variety itself controls the tree size for avocados.


That’s good to know thanks! I planted a small hass seedling and am looking to graft a b type on there to help pollinate these two trees a little. However in different climates they flower at different times so I can’t necessarily go by Southern California info which is basically where most of the info and studies come from. You’re leading the way up the in Seattle for this delicious fruit props for what you do.

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Just did a survey of some of the trees that were unprotected or only minimally protected during the January freeze. Definitely looks like a few will regrow from around ground level. Here are just a few of them. The links for each of these go to their profile page on the project website, which gives some background on each of them:





#149 (this one had an unheated single layer of fleece cover):


How is your big tree doing? Did it keep its leaves?
Sorry if I missed it in the thread.

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Not exactly! Though it does still have one leaf with a hint of green that hasn’t fallen off yet:

Here’s the link to the profile page for that tree, with other recent photos:

Seedling #37

That tree was covered, but still had a pretty cold freeze (low ~19°F), since it was not heated. The sensor “Floater 1” was inside its enclosure:


I just ran a comparison between what the covered tree #37 experienced in the January freeze and what the unprotected trees experienced. They both were cold, but it was a lot fewer hours in the worst freezing range:


Thank you for the extensive information. I know Brokaws rootstock. Unfortunately they don’t sell individual trees. But I was also more asking this from a breeding perspective.
I was wondering if someone already had tried to combine the cold hardiness of the Mexicans with the short ripening season of some West Indian avocado’s
But it looks like it may be something that I myself should try. If I can keep a WI cultivar alive in my unheated greenhouse here…

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Mexican varieties already have some of the shortest ripening seasons of any avocados out there. Mexicola is only about 6 or 7 months from fruit set to maturity, and most pure Mexican types are under 9 months.

Unfortunately, this is not really a data point that has been published as much as it should be, though. You might find, for example, a list of the months when a particular cultivar is ripe in a particular location (usually southern CA), but rarely is that accompanied by the flowering dates. And especially for Guatemalan types and their hybrids, you could be deceived even if flowering dates were given, since some of those take 18 or even 20+ months to ripen.

You might hear that WI varieties are “earliest” but you should ask when they flowered! They are mostly grown in the subtropics and will often flower in the fall season, while Mexican types flower in late winter. Therefore, even if the WI type ripens earlier, it may not necessarily have a shorter time from flowering to ripe fruit.

Once my greenhouse trees start holding fruit (this year??:crossed_fingers:), I’ll be closely tracking and sharing the time from flowering to fruit maturation for all my varieties, most of which don’t seem to have that published anywhere at all.


My in ground poncho pushing new growth assuming flowers to follow. Lila also pushing some new growth but behind the poncho


I wouldn’t assume that. Usually flowers come with the first flush before the leaves. My Poncho has not yet flowered, it’s starting its third season since grafting currently. Here’s mine, looks like only vegetative buds again this year:


You know what you’re right just looked into last year and it was full bloom Jan 29th

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I’ve come upon new information.

Just last January I went down to Chile to visit family for the first time and attend my brother’s marriage.

My brother is very into plants, has his own little plant propagation lab, and an entire small-scale decrotive plant businesses to go with it.

When I left his place on my way back to the states, I noticed something that looked like two avocado trees in his neighbor’s front yard.

Earlier in my stay, he’d told me that unlike the nearby mountainsides of hass, that his area actually gets cold. He says that last winter it got down as low as -8 C (17.6 F)

After constantly bugging him since then, today I got him to ask his neighbor about it.

His neighbor says that they’re 15 year old Palta Negra de la Cruz tree. (Palta is avocado in Chilean spanish) Apparently they defoliated last winter, but it hasn’t seemed to slow the trees down much:

Pictures I took on my drive-by:

Picture my brother took today:

It is not ripe yet, apparently they’ll turn black like hass when ready.


Interesting! Thank you for sharing that. The bumpy skin looks more like a Guatemalan type or hybrid, so that really would be pretty hardy if that’s the case. When I tried googling the name, the photos all look more like Mexicola Grande or something, but probably are just stock photos anyhow. Not much information about the variety online from any kind of reputable looking websites.

I don’t think my brother really knows much about them either; the giant, tasty hass are all the craze down there. I believe his dad knows more though, in fact, he was the first to tell me about this variety. He’s visiting my sister in Temecula, so I’ve now been trying to call for more information.

Nearly everything that I can find on it make me practice my Spanglish, but it seems that its a cross between a Guatemalan x Mexican and most places indicate a cold hardiness of -5 C (23 F). I still can’t figure out the skin difference though.


Here’s LSG, and even though it’s primarily vegetative, it looks like it might be hiding a couple flower stalks in there? Either that or branches, I think, but it’ll be clearer in a few days:


I got more information on Negra de la Cruz, sounds like the mexicola-like pictures are accurate. Maybe those trees next to my brother’s are some weird hass thing, I don’t know.


I’ll check it earlier this year but my sense is that someone isn’t stripping it. It’s HUGE.

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First flower to open in the greenhouse this year! Walter Hole wins the race this year:

Looks to be almost finished with :female_sign: stage but hasn’t started dropping pollen yet. I’ll probably throw this one in a little jar as a pollen source in the coming days, since there’s no way it has been pollinated.


Had a great tree distribution this weekend, so far I’ve handed out 43 trees this year, with about a dozen left to go. Next year’s trees are liking the recent sunny days, you can almost watch them grow. Here’s #390, a seedling of a tree in Gainesville, FL that is believed to be grafted with “Joey,” though not confirmed:


Actually @Gkight I take it back, looks like at least a single flower cluster emerging on Poncho after all:

Long South Gate also has just one so far, though has a few branches that are a lot further behind this one: