The great Seattle cold-hardy avocado trial begins

Royal Wright seeds could be candidates for rootstock. That tree is also very vigorous and precocious. I have two seedlings in ground and they grow fine. Royal Wright seedlings vary in phenotype. I left for myself 2 that are very different. A tall and vigorous one, and another could be a dwarf one. The time will show

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I’m planning to plant out dozens of seedlings over the next few years and hoping the genetic variability of drymifolia will unexpectedly produce a tree capable of surviving the cold and wet Seattle winters. If I find one that can make it, the plan is to let it grow until it fruits (if it will here), rather than using as rootstock.



P.S. Oddly enough the Hass newborn/sprout that hadn’t even put out its first leaves still looks fine. Didn’t take a picture before night fell but I’ll update on it in a few days.

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Been a little while since my last update, but not a lot has changed, so this should be a relatively brief one.

First off, the Mexicola seedling that I said RIP to isn’t dead yet!! I didn’t take a picture, but I dug down gently and a new shoot is already pushing up through the soil from the seed/roots. I have decided to give it shelter from the upcoming cold snap, and covered it with a bucket with an LED bulb (12w) since I didn’t have anymore incandescent string lights. I’ll post a photo of the new shoot once winter releases its grip.

Next up, in grafting news, the 5 scions that I ordered from A Natural Farm via their Etsy shop look like they were a bust. Turns out the buds that were swelling were flower buds, and they pushed out prematurely, then stalled, and three out of five are definitely dead now. Fantastic and one of the Joey scions appear to be clinging to life, so at best it might be 2/5, but maybe 0/5. I can’t blame them entirely, as that was my first attempt to graft and I didn’t do a great job, but the flowering thing was the nail in the coffin.

It is a completely different story for the 14 scions from Marta, which still look great, most of them dormant-but-green, but a few starting to push, like this Royal-Wright:

I also have 8 Royal-Wright seeds I ordered from Marta (counting the one still in the fruit!), which came today and are getting their warm bath before sowing:

None of the Bacon seeds have sprouted yet, but one is showing me its crack so it’s just a matter of time:

Greenhouse is still in planning phase, but I’ve gotten one quote for materials and two for labor, waiting on one more of each before deciding how to move forward.

That’s all for now!


I didn’t realize there was so much variability in the shape of avocados. I’m sure there is plenty different tastes as well. Maybe I’ll have to look into grafting the seedlings I have from store bought fruit!

I am thoroughly enjoying the updates on this thread. The one question I keep thinking to ask, is- Have you considered sheltering all of your seedlings with a 5 gallon bucket (or similar) at least through the first winter? I know you are going for a cold hardy tree, but take pawpaw for example. Even in their native range, they still prefer to be coddled and protected from full sun their first couple of years, but afterwards they thrive in full sun and are cold hardy etc. I wonder if a similar situation would arise for avocados in your area? Protect for a year or two and they might be hardy enough on their own afterwards… Or maybe mulch around them instead of a bucket? Just throwing out ideas here.

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I’m planning to keep them in pots in the greenhouse for their first (and maybe second) winter, other than when I “euthanize” seedlings that are suffering in their pots, like that Mexicola one that had a bad case of root rot. Rather than killing it outright, I figured it couldn’t hurt to plant it out early instead.

Any exceptions (e.g., I’m thinking of planting a couple seeds directly in the ground as an experiment) will definitely be given maximum protection for a couple winters, with buckets or blankets, string lights, all the works.

The biggest challenge will be protecting them from our winter rains, where even well-drained soil, mounded, will get completely saturated. Avocados are notoriously unhappy with saturated soil. I know people who grow cold hardy citrus in the PNW often have to do something similar, building a rain shelter or using patio umbrellas over them during winter months. Hopefully once they get well established they’ll be able to withstand it better, or maybe I could get creative with tarps/rain flies attached to the trunk to guide the water away.

Do you know if Royal-Wright, Duke, or Aravaipa are type A?
I ordered Bogdon and Lila scions from A Natural Farm and only the Brogdon took …so I’m looking for another type A scion.
Just experimenting in ghouse.

Maybe even a roll of heavy duty contractor garbage bags would work as a rain “skirt”. I’m glad you are keeping them protected through their infancy. Murdering baby avocados purposefully, even in the name of science, is a sad thing to think about :joy:

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If you’re just going to have them in a greenhouse then you’ll probably be hand-pollinating and flowering type won’t matter as much as long as you brush the flowers a couple times each day to collect pollen and pollinate. Also, flowering times vary a lot based on temperature, so it’s possible Brogdon won’t behave like Type B in your greenhouse.

I’d offer scions, but the only cultivar that I have with any extra branches at the moment is Brazos Belle, also Type B.

I don’t know about flowering type for Marta’s varieties, though.

Thanks for pollination details re: greenhouse. Will be quite a mystery to explore!
Another question: If I am hand pollinating, would I still need another variety (either A or B) or could I hand pollinate a single Brogdon plant, saving pollen from morning to evening?

I contacted Marta. She has scions of Duke, Aravaipa, and Royal-Wright but wasn’t sure about their A or B status. She said she would check once they bloom in spring.
Thanks, Chris

From the research I’ve read, most avocados are self-fertile other than the flowers shedding pollen at a different time of day than they are receptive to pollen. And depending on temperatures, there can be a significant overlap.

I did read one study (don’t have it handy or I’d link) where they did genetic analysis of seedlings and found that many self-pollinated (Hass x Hass) seedlings died mysteriously shortly after germinating, and none of the crossed (Hass x Bacon) seedlings had this issue. But it was a relatively low percentage in any case.

There are also some reports of lower levels of premature fruit drop when cross-pollinated vs self-pollinated, but many commercial orchards are single-cultivar, without pollenizers, so clearly that’s not a major factor either.

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Thanks. A lifetime of learning.
Then I’ll go with some scions from Marta and see what happens!

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This might not be the BEST place to put this, but I can’t help myself. Avocado, baby by Los Campesinos!

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Here’s the study I referenced above, and they found that 24% of the Bacon x Bacon seedlings had a lethal mutation, 46% of the Hass x Hass seedlings had a different lethal mutation, and none of the Hass x Bacon or Bacon x Hass seedlings had either mutation.

So even though avocados are self-fertile, it does look like there’s a good reason to cross-pollinate if you intend to plant the seeds.

[23279834 - HortScience] Outcrossing between ‘Bacon’ Pollinizers and Adjacent ‘Hass’ Avocado Trees and the Description of Two New Lethal Mutants.pdf (1.4 MB)

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Thanks. Similar to marriages of familial nobility, recessive genetic traits emerge in offspring. Makes me wonder about saving the seeds from any plant that self pollinates, e.g tomatoes! Hybrid vigor must be good.

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I’ve decided to do a post that sums up some of the useful avocado-specific documents/websites that I’ve been reading lately, in case anyone else wants to read up on this stuff.

First, Propagating Avocados (1989), a publication of the University of California that summarizes grafting and seedling sprouting techniques used by commercial nurseries and avocado growers in California.

Next up, the web-published guide from the Western Australia department of agriculture, Challenges growing Hass avocado in cool regions. I have no intention of growing Hass, but much of the research summarized there is more broadly applicable to avocados in cool climates, including how colder temperatures impact type A and B avocados differently.

Then more generally, I have to plug, where I’ve found countless obscure documents and studies with interesting results, including:


Here’s more of an update on the avocados I’m currently growing. A family photo album of sorts?

Grafted varieties

First off, some success stories from my first attempts at grafting avocados.

Joey on grocery store Hass seedling rootstock (pushing a flower bud, but looks like it’s taking):

Aravaipa on the Choquette frankentree:

Royal-Wright, also on the Choquette frankentree (and also pushing a flower bud but appears to be taking):

Sadly, it appears that Lila, Fantastic, and the other Joey graft all failed, and Brogdon is likely failing as well though it still looks somewhat green.

As a new addition, I grafted three scions of Duke this week, one onto the Choquette frankentree, one onto the Brazos Belle frankentree, and one onto some Hass seedling rootstock that I planted out in the yard just for kicks. I’ve never seen an avocado with such a yellowish looking color to its stems, but that is what I’ve heard about Duke so I will assume they are healthy scions. Here’s the one in the yard:

I have four main “frankentrees,” each frameworked on an already-grafted variety that I bought at 5-gal nursery pot size last year, all on Lula rootstock, and currently in 12-15 gal pots indoors. These are the grafted varieties that are forming the framework for the frankentrees:

  • Choquette (not hardy)
  • Winter Mexican (not very hardy)
  • Poncho (hardy)
  • Brazos Belle (hardy)

The latter two I intend to eventually plant out, but only when they outgrow my greenhouse. I’m hoping to keep the Choquette and Winter Mexican trees pruned to fit in the greenhouse, and will be continually adding and removing varieties depending on what does better outside. Here are the Poncho and Brazos Belle trees (didn’t take photos of the other two, which are ugly now with lots of grafts on them anyhow):


I’ve got quite a few batches of seeds currently germinating, either to test for hardiness themselves (Mexicola, Mexicola Grande, Bacon, Royal-Wright, alleged Fantastic and Del Rio from Etsy), or for greenhouse/rootstock use only (Sharwil).

The germination technique that I’ve settled on is based loosely on the one described in the pamphlet Propagating Avocados, where the seeds are placed in moist native soil in tight rows and observed for germination, after which they are transferred into nursery pots. Instead, I use take-out containers with damp soil on heating pads:

Then, as the taproot emerges, I move them into their own pots. Here are some freshly potted up:

Most of the seedlings are still inside under lights, like this Mexicola Grande:

And here I’ll finish with a photo of the strangest little seedling of them all – a Mexicola seedling that had the smallest seed I’ve seen yet, and is now producing a tree with the smallest leaves I’ve ever seen for an avocado:

It is currently not in great soil (too much native soil in the mix), so hopefully it holds out nicely until I can re-pot it in the greenhouse in a month or so. So far at least, no real signs of any problems other than its small size and very small leaves.

OK, that’s all folks! Hopefully my next update can be when the greenhouse is built and the plants start moving in.


Decided to plant out the less vigorous Mexicola seedling, which had already been in a shady corner of the patio full-time (about 5 nights below freezing in two weeks, one 27.7° and the rest 29-31°)… and now I know why it was less vigorous!

Looks like the seed split in half when I planted it, so it’s been getting only half the seed energy it should have. Interestingly enough, the other half has now germinated, so I planted it back in a 1 gal pot to come under the lights with the other recently germinated seeds:

Speaking of trees under the lights, the grafts of Aravaipa and Royal-Wright are starting to push out their new leaves nicely:

Greenhouse construction starts in 2 days, I’m looking forward to introducing the avocados to their new home. So I’ll close with the Mexicola seedling out in the yard, future greenhouse making a cameo in the background:


Just got my latest batch of seeds from someone on another forum, which is an unnamed seedling-grown drymifolia variety the grower described as “the oiliest avocado [he’d] ever tasted,” almost like “avo cream cheese.” Here’s a photo that he sent of the fruit:

I cleaned off/peeled all the seeds and threw out one that looked like a fungus had taken hold, planted one that was already germinating, and here are the remaining 8:

One interesting feature, 3 out of 9 (didn’t check the infected one) have something I’ve never seen before with avo seeds, where instead of being in two sections, the seeds are divided into 3 roughly equal ones:

It’ll be interesting to see if these grow any differently as a result.

Onto the heating pad they go:


Since you’re an avo murderer, I thought you might know about the “forensics”. I hope to not join you in murder by the way.

I noticed on a recently purchased tree from a nursery leaves exhibit splotchiness or a mosaic pattern. Subtle but there in most leaves… normal? Virus?

Sun behind the leaves in the photo bring it out, otherwise leaves are deep green and hard to see the described symptom.