The great Seattle cold-hardy avocado trial

Believe it or not I’m pretty new to avocado growing, so not sure what that leaf shows. It could be something as simple as a touch of sunburn, I have never heard of viral problems like that though.

The oldest leaves usually get kind of discolored and splotchy for a few weeks before they are dropped, so it could maybe be the start of that, though usually that doesn’t happen until a new vegetative flush is pushing.

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I see you’re in Seattle. I am down in Tacoma, and I REALLY want to plant an avocado, but everyone calls me crazy.

What variety do you think I should get, I was thinking Mexicola or Lila.

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They probably are correct, and I’d say any commercially available grafted tree will probably be on rootstock that’s even more unlikely to survive here than the grafted variety. But the purpose of my testing is to see if it’s really such a crazy idea.

If you’ve got a good protected spot (mostly sunny, against the south side of a heated building, well-drained soil), and are ok with a likelihood of failure, then I would say go with the hardiest variety you can get your hands on, Lila/Del Rio/Wilma/Poncho/May are allegedly more hardy than Mexicola/Mexicola Grande.

If you want to really gamble a bit and can wait a year, I’ll probably have more hardy seedlings to plant out next spring than places to plant them if all goes as planned. If so, I’d be happy to share one or two. I’d suggest growing the seedlings for at least a year to test winter hardiness before grafting anything else on it.

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How hardy would you expect them to get? 32F death, 20F death, etc? I have lows to 12, so I doubt I’d ever be a candidate in 7b, but I’d love it if I could!

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Yeah, you’d need a cold frame there I think. Once established and mature size, the hardiest varieties can allegedly withstand lower 20s without damage and survive mid-10s with significant damage, but probably not if the ground freezes solid.

I have not tested those claims yet, but the tiny Mexicola seedling that I planted a few days ago appears to have suffered only slight damage after being out in a pot on my patio for lows of 28, 29, 30 spread out over a two week period, and in the ground for 27 and 28 on consecutive nights. So that bodes well if a tiny tender seedling can survive that relatively unscathed.

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My greenhouse is running behind schedule, so I thought I’d do a “baby photos” update as the last one before the big move.

I’ve got quite a few seedlings germinating, which will be among the first trees I will plant out that could have any real hope of survival (in about a year). These are all from seeds that I got from other growers, and have unknown pollen parents (though likely many are self-pollinated). Therefore, their hardiness will be even less certain than the crosses I’ll be making myself over the coming years.

If none of this first round make it I’ll keep working on the greenhouse frankentrees and start crossing the various varieties more intentionally.

First off, some of the oldest seedlings, these of Mexicola Grande:

You may notice they don’t look so great, but they are both just starting a new vegetative flush. Their sickly demeanor is a result of spending 4 weeks on the patio in winter to test hardiness at this size. Over that period, they experienced five nights below freezing, including consecutive nights of 28 and 29°F. I brought them in 2 weeks ago to avoid a 27° night, and decided to let them stay under the lights as a reward for surviving that ordeal. I left one outside in its pot, and it’s still alive but suffering a lot (no photo this time around).

Next up, the newest additions, three of the seeds I had just started germinating in my last update (“Purple Cream Cheese”) that already had taproots emerging yesterday, very rapidly compared to most other avocado seeds I’ve germinated:

Here’s a couple Bacon seedlings that spent those same 4 weeks of winter outside, but much earlier in their development (one immediately upon germination, the other 2 weeks further along):

Finally, a few of the Royal-Wright seeds that are just beginning to sprout, including the last one that was having trouble splitting its seed, so I just gave it a little help with the grafting knife:

And as a teaser for next time, a photo of the still unfinished greenhouse (getting close!)

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Looking good! I have “space for a greenhouse envy :grin:” I have to make do with a grow light and a tiny room below my basement steps like Harry Potter right now haha.

How long will it take to get fruit on the frankentree? I have 2 seedlings in the HP room from grocery store seeds and I’m not sure I’ll ever get them to fruit in Pennsylvania, even under the light inside all winter.

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Out of my 4 larger grafted trees destined for the greenhouse, I’m expecting two of them to start flowering within the next year, since those are already a couple years old and I’ve only added a couple small grafts on each one (I won’t allow those new grafts to set fruit that soon, even if they try). So, hopefully I’ll get Brazos Belle and Poncho to flower in about a year, with first fruit the next winter.

The two most heavily grafted trees are almost entirely new scions, so probably at least two years until I’ll let those set any fruit.

As for your seedlings, my vote would be to graft something onto them for a better chance of fruit, but as long as you’re letting them out from spring to fall, they might still bear fruit eventually on their own. My understanding from the literature (not personal experience yet) is that most seedlings start to flower when they reach around 8-12’ in height, with poor fruit set and fruit quality for their first few years. How long it takes to get that size in those growing conditions is the real question. They also usually flower after cold (though there’s wide variation among varieties on flowering time), so you may want to move them out slowly early in the spring to let them get a bit more cold in the hope of triggering earlier flowering.

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I will check back in with you in a few years and see what you come up with haha

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I’ll let you know how the 50+ foot tall mexican seedling planted in 1990 faired in our recent artic-mageddon week of freezing weather to 14F that is located in Lake Jackson, TX. I saw it shortly after the freeze and it wasn’t looking too good. It is 24+ inches in diameter at the base. 1989 was the last artic freezing event here. My friend did prove that the A/B blooming trees don’t matter in bearing fruit here in Texas. His lone tree keeps the squirrels well fed with “guacamole on the half shell.”

I know of several insane people that keep re-planting avocado trees in the Houston, TX area 8b/9a zone. Insane in that they insist the 21st tree they plant won’t freeze like the first 20 in a row did. Good luck to them and you.

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This is a very long term project where I fully expect most of the seedlings to die, but I’m happy to look forward to some productive trees in the greenhouse, and if I do manage to breed a tree that is hardy here (which I accept is a long shot) then that would be a bonus really.

I do hope that seedling tree near you manages to regrow from the main branches, and if so then some day I’ll have to try and get some seeds or scionwood from it!

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It’s been a bit, so thought it might be a good time for an update on the growing family of avocado trees whose demise I’m plotting.

Since my last update, I’ve moved most of the germinating seeds and seedlings into the greenhouse, and the seedlings in there alone are starting to get too numerous for a family photo:

There are also two aspirational frankentrees in the ground in the greenhouse:

I also have a largeish Poncho tree grafted on West Indies rootstock, so I’ve hesitated planting it out, but it’s doing ok in the greenhouse and even has a stray flower bundle almost ready to open:

Finishing out the in-greenhouse collection, my first successful graft of Joey on a Hass seedling:

Next up, for the outside avocado trees, starting with the original Mexicola seedling that I planted out in the middle of winter, intending it to be euthanasia because it had root rot.
However, it is now pushing two new shoots after experiencing multiple hard frosts and a colder than normal early spring:

All the other seedlings that were planted out prematurely (other than a Hass) are pushing new growth and looking ok considering the multiple frosts that I expected to be too much for such small seedlings (these are Mexicola Grande, Mexicola, and Mexicola Grande seedlings):

The Mexicola seedling that has been outside in its clay pot is looking the best of all the outside trees:

While on my trip to Florida over the last few weeks, I met up with Oliver Moore in Gainesville and got a seedling of either May or Del Rio, grafted with Jade and another ungrafted May/Del Rio seedling that had nice smelling leaves and vigorous growth. They’re in the mail now, so will have to wait for the next update to share photos!

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Is there a murderers anonymous or something, I can join?
I think this is my third tree that’s on it’s way out. Not sure what’s causing tip browning on the new growth, nibbles off new leaves, and spider mites that REFUSE to die after 3 drenchings of Neem oil. Grrr

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The browning of older leaf tips looks like salt buildup, but the newer leaf issues looks like insect/mite damage.

What’s your mineral content in your water? Might be time for something more than neem if those mites are that persistent…

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Yeah, I knew the older leaves were a salt buildup, but I’ve never seen such aggressive mites. I’ve literally soaked the tree 3-4 times.

Any recommendations for something stronger?

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I’m using Ortho Tree & Shrub Fruit Tree Spray against Aphids.It does contain Neem and a couple other things.Spider Mites are listed on the label.
https://www.ortho.com/en-us/products/garden/ortho-tree-shrub-fruit-tree-spray-concentrate

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Pyrethrins and soap have been my go-to bigger gun for aphids, in cases where neem isn’t enough. Monterey’s “Take Down Garden Spray” concentrate is a good pyrethrins source, and I mix it with concentrated insecticidal soap like Natural Guard’s. For smaller or spot application, Safer’s “EndAll” RTU spray works well. It’s pre-mixed pyrethrins, soap, and neem.

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Thanks guys. These are stubborn.

The two trees that I mailed to myself from Florida appear to have survived the journey (a little worse for the wear), and I’ve repotted them so they can settle into their new home:

Here’s a photo of Jade fruit: https://www.instagram.com/p/B2HC2KAgebg/

And here’s the description copied from the Instagram post above:

Presenting ‘Jade’, the newest cold-hardy avocado variety. These fruits are from a seedling tree which is making its first-ever crop of fruit this year, and wow are they fantastic.
A number of us here in North Florida have been planting out seeds from good named varieties of cold-hardy avocado. This mixing & matching of genes has produced some good-fruiting new avocado trees, but one young seedling tree in particular really caught our attention this year with its superior fruits. It is clearly worth propagating, so we gave it the variety name, ‘Jade’. The black-skinned fruits of ‘Jade’ are larger than many of the cold hardy Mexican-subspecies varieties (we weighed one at 5.6 oz), with a good flesh-to-seed ratio, and an outstanding flavor. The taste has the rich, oily flavor of other Mexican varieties, and a creamy, mayonaise-like texture. The thin edible skin is pleasant-flavored, with little of the piney flavors some types have.
My friend Oliver brought several ‘Jade’ fruits to an avocado-growing workshop he presented this week, including this exciting new variety at a tasting table with samples of a number of other cold-hardy avocado varieties that are currently ripe. All the avocado samples were delicious, but most people’s favorite was ‘Jade’. A number of attendees asked if they could buy a ‘Jade’ tree, and we had to explain to them, “Right now there’s only one tree in the whole world of this variety, and you’re among the first people who’ve gotten to taste its fruits!” There’s one cloud over this exciting new cultivar: the owner of the land where the ‘Jade’ tree is growing is in the process of listing the property for sale. We will likely lose access to this outstanding tree, and if the new owners don’t find value in having fruit trees, they could remove it.
So the day after the avocado workshop, Oliver and I drove out to the property on a mission to rescue the ‘Jade’ avocado, and we attempted a number of methods to propagate the tree. Hopefully we’ll be successful, and this outstandingly promising new avocado cultivar won’t get lost, so many more people can enjoy its rich, creamy fruits in future years.

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Love the ‘Jade’ back story!

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