Dreaming of Cascadian avocados

Hi everyone! I hope this thread isn't too redundant since there's already the European cold-hardy avocado thread, but figured it was worth having a separate thread for our bioregion, despite some similar challenges.

I'm pretty obsessed with the idea of breeding avocados for not only "cold-hardiness" (i.e., ability to withstand brief freezes in otherwise favorable climates), but also what you might call "cool hardiness," or the ability to survive cool maritime climates with long, dark, wet winters hovering just above and below freezing for months on end.  An avocado adapted to the Cascadian lowlands!

My obsession began way back in late 2020, when I read Craig Hepworth's blog post about the Mexican botanical group (or "race" if you prefer, but that term carries some baggage) of avocados, Cold Hardy Avocados: Guide to Cultivation and Varieties.  I ordered a few grafted trees, and began digging in deep in the published literature, as well as reaching out to other cold-hardy avocado pioneers, including Craig, his friend Oliver Moore, the staff at UC Riverside who maintain their research grove, and others. I began collecting seeds, scions, and skills.

By spring 2021, my obsession had taken full hold. We converted our somewhat dilapidated 1-car garage into a greenhouse, I started finding other people who wanted to join the effort, both locally and around the world. Thus was born the drymifolia collective. But at that point, I had only a handful of trees. Over the summer of 2021 I planted out a dozen or more seedlings of varieties like Mexicola, Mexicola Grande, Bacon, and Royal-Wright. I planted two multi-graft trees in the greenhouse, hardly more than little sticks. I didn't have enough extras to distribute trees to anyone else that year.

I was hoping we'd get a few years before we had our first test winter, but my hopes were dashed. From December 26, 2021 to January 1, 2022, we had six full days with the high temperature around or even well below freezing, starting with a night down to 18°F and ending with a low of 16°F on the last night. I was sure that everything was dead, and above ground nothing made it. No surprise, those were little seedlings.

By the next summer it was clear that some of them weren't going to come back, but a few of them grew back very vigorously from their roots. So, of course I got more scions, more seeds, and found more comrades.  I planted dozens more plants in the ground, and started distributing some trees to project members, though just a few that year.

The next winter, I said to myself this will be the winter with no bad freeze. But it was La Niña, which means cold. Winter low was 17°F. I protected a few things with buckets or upside down flower pots. Some surprise survivors, though! Poncho (grafted) had no damage under a flower pot. A few seedlings even had a few inches of their trunk survive above ground! And we got our first large donation of seeds (~80) from a generous comrade in north FL.

Which brings us to this year, which was my first big distribution of trees to project members, about 30 trees scattered throughout lowland Cascadia, tucked into different microclimates. And with an El Niño winter ahead of us, maybe we'll finally get a mild or at least normal one, so some of the trees can get larger and more able to withstand future winters.

Currently we've got about 150 seeds starting for 2025 distribution, 50 or so one-year-old trees ready to be distributed to members in spring, and the greenhouse trees are about 8 feet tall and hopefully ready to actually set fruit next year! Around my yard are about 40 trees, mostly with only a single year of growth.

I'll finish up this post with a photo... Here's one of the original Mexicola Grande seedlings (tree #37), germinated over the winter of 2020/2021, which was one of only two potted seedlings to survive that 6-day freeze outside. I kept it in a 15 gal pot last winter in the greenhouse and planted it in the ground this March, so it is in the ground for its first winter now... the tallest outdoor tree at about 8 feet tall:


I probably won't post too many updates here, but happy to answer questions or collaborate, and of course anyone who wants to join the project is welcome, though earlier members do get higher priority in tree distributions, at least until we start producing enough seeds to exceed member demand for trees . At this point we're just selecting seedlings from seed sources outside our region, but hopefully next year (and for many years after that) we'll actually be crossing our own varieties and selecting based on proven hardiness in our climate.

This sounds like a great project Winn!

You're not the only one dreaming of Avocados - but it does sound as if your ecosystem is harsher than mine. I've done a little reading, and if I can get some other projects finished, I was thinking of trying to start some Mexican Avocados, although I wasn't going to worry about specific named cultivars - I'll take "mutts" on my homestead, so long as they're healthy, as I'm not trying to get huge production.

I'm really bothered that North American demand for avocados is resulting in people in Mexico being pushed off their land and monocultures replacing polycultures. If we work on being able to produce them further north, that seems like a win to me.

Jay Angler wrote:
I've done a little reading, and if I can get some other projects finished, I was thinking of trying to start some Mexican Avocados, although I wasn't going to worry about specific named cultivars - I'll take "mutts" on my homestead, so long as they're healthy, as I'm not trying to get huge production.

In case it wasn't clear, our project is primarily growing seedlings of allegedly cold-hardy varieties, but avocados show quite a bit of variation among seedlings, so they are all "mutts" other than the grafted varieties that are intended to be seed sources more than anything else. I do distribute grafted trees some, but mostly seedlings.

I'm really bothered that North American demand for avocados is resulting in people in Mexico being pushed off their land and monocultures replacing polycultures. If we work on being able to produce them further north, that seems like a win to me.

100% agree! Not just in Mexico, everywhere that avocados are grown commercially they are monoculture and not only that, they are nearly 100% "Hass" so it's both monoculture and genetically uniform. And they use so much water that it's irresponsible to grow them on a large scale anywhere with water shortages.

One thing we've got plenty of here in Cascadia is water, and even if climate change reduces that somewhat, most of the models show us still getting pretty reliable rainfall in winter here. But more importantly, when they are grown in diverse food forest settings, the water needs aren't so extreme, and they can handle drought pretty well.

Winn Sawyer wrote:One thing we've got plenty of here in Cascadia is water, and even if climate change reduces that somewhat, most of the models show us still getting pretty reliable rainfall in winter here. But more importantly, when they are grown in diverse food forest settings, the water needs aren't so extreme, and they can handle drought pretty well.

Our rainfall tends to fluctuate with El Nino/La Nina. We have a big field where our chickens/ducks/geese hang out and I'm amazed how much longer the grass stays green as the summer drought progresses with all the soil building we've done in the lower areas. The area where I'm trying to get bits and pieces of a food forest started is a mix of dirt disturbed/abused by a former owner, glacially compacted subsoil-like stuff, second growth cedar that's struggling, and a lot of invasive English Ivy, Himalayan Blackberry, Morning Glory and Canada Thistle. It takes a lot of work to get it ready for trees. So I see better water retention as a result of my efforts, but it take more energy than I've got, so the progress is slow.

I'm glad to hear you say that Avocados should cope with our climate if we do it right!

Jay Angler wrote:The area where I'm trying to get bits and pieces of a food forest started is a mix of dirt disturbed/abused by a former owner, glacially compacted subsoil-like stuff, second growth cedar that's struggling, and a lot of invasive English Ivy, Himalayan Blackberry, Morning Glory and Canada Thistle. It takes a lot of work to get it ready for trees. So I see better water retention as a result of my efforts, but it take more energy than I've got, so the progress is slow.

That all sounds very familiar! I have a nice sandy loam as my topsoil on top of the compacted glacial subsoil, but before we got this place in 2020 it was almost all grass, just two mature trees on opposite corners of the lot. Anywhere not mowed was English ivy, Himalayan blackberries and bindweed (morning glory). After some very stubborn physical battling, I've eliminated the ivy and pushed the blackberries into the fenceline at least. The bindweed will never be defeated that way, I fear, it has roots down to the heart of the earth itself.

Getting a "chip drop" has been a game changer for my battle against grass and other weeds that grow in grass-dominated soil biomes. The avocados seem to like the glacial soil, especially when they get a heavy mulching with wood chips. The wood chips also seemed to get the other stuff going better, like the feijoas, mulberries, figs, and peach. I'm hoping maybe it'll help keep the bindweed at bay, but so far doesn't seem to be slowing down its rate of new shoots every summer.

This is a thread of high personal importance to me. I too dream of avocados. I appreciate the sharing here because I have no personal experience to add.

Thanks!

Has anyone been trying to make crosses to some of the related North American species?

Greg Martin wrote:Has anyone been trying to make crosses to some of the related North American species?

I believe that Persea does not readily hybridize even within the genus, but I'm not aware of efforts to overcome that with techniques like embryo rescue or whatnot. Avocado isn't even graft compatible with some other species on the continent like swamp bay P. palustris or red bay P. borbonia.

The California bay laurel Umbellularia californica probably most closely resembles an avocado fruit, and the flowers are highly similar looking and even open during overlapping times, but since those grow throughout the commercial avocado growing regions of CA, I assume a chance hybrid would have occurred if it were possible.

I don't think any hybridizing is necessary for a Cascadian avocado, just a large and diverse starting gene pool and thousands of seedlings being tested. But maybe in the end I'll be wrong and nothing will make it here until we move to zone 10 in like 50 years or whatever.

Hello Winn, sounds like a cool project. I too have the desire for avocados here in Southern tip of Illinois. We have two trees not sure of variety just seeds we started in 2015. They were kept in 30gal pots inside greenhouse first part of their life, now they are planted in the ground inside a greenhouse that we heat over winter keeping Temps above 40° at lowest. We have gotten flowers and some marble sizes fruits but then they just drop off for the last 2 years. I'm wondering if it's a pollination issue, they begin to flower late February-March so only insects we have around are lady bugs, praying mantises, and some predator mites that we release to keep pest issues down. Pest really like our greenhouse in the fall cuz it stays warm lol. Once we finally start getting fruit I may start trying to climatize some of our "native" seeds to our outdoor climate since they will already have our 37°N latitude sunlight acclimatized. Only thing they will need to adjust too then will be the Temps. How would you go about identifying your avocado variety?

michael rowald wrote:Hello Winn, sounds like a cool project. I too have the desire for avocados here in Southern tip of Illinois. We have two trees not sure of variety just seeds we started in 2015. They were kept in 30gal pots inside greenhouse first part of their life, now they are planted in the ground inside a greenhouse that we heat over winter keeping Temps above 40° at lowest. We have gotten flowers and some marble sizes fruits but then they just drop off for the last 2 years. I'm wondering if it's a pollination issue, they begin to flower late February-March so only insects we have around are lady bugs, praying mantises, and some predator mites that we release to keep pest issues down. Pest really like our greenhouse in the fall cuz it stays warm lol. Once we finally start getting fruit I may start trying to climatize some of our "native" seeds to our outdoor climate since they will already have our 37°N latitude sunlight acclimatized. Only thing they will need to adjust too then will be the Temps. How would you go about identifying your avocado variety?

Getting flowers from seed in only 6-8 years is not bad! Because they are seed-grown, they are a brand new variety, avocados have a lot of variation and are nowhere near true to seed. They are probably seedlings of Hass, so they will likely be similar to Hass in some ways and different in some ways. They will likely take 14+ months to ripen once they start holding fruit.

As far as your difficulty with fruit set, that could be a pollination issue, a temperature issue, a water issue, or just normal fruit drop.

You can try hand pollination for one branch to test if that's the issue. Each individual flower on an avocado tree opens twice: first in a pollen receptive phase (no pollen released) then it closes and within 36 hours (depending on whether they are Type A or Type B it is either later the same day or the following day, in cool temperatures could be up two days later), it reopens to shed pollen. If your two trees are both the same flowering type you will need to collect pollen at a different time of day than you apply the pollen. If you lucked out and got one tree of each type, then each one should be shedding pollen when the other one is receptive.

I suspect you may also have a temperature issue. When avocados flower below a certain threshold (low 50s°F for Hass), the pollen tubes fail to form correctly, and even if pollen is applied to flowers, embryos fail to form, and the fruitlets are aborted. To avoid this, you should either increase your heater during flowering, or decrease your heat over the winter so that flowering is suppressed until later in spring when your low temperatures are warmer.

If pollination is happening and temperatures are good, the most common cause of excessive fruit drop is insufficient water. Avocados get very thirsty during their spring/summer growth, and they will abort fruit if they are not getting enough water.

But even if all of those are OK, avocados are notorious for dropping nearly all the fruit they set. A large mature tree will have well over a million flowers and usually only ripens a few hundred fruit. So your trees may just need to get bigger.

Here's a publication from Western Australia that has a great discussion of the biology of avocado pollination and fruit development in cool climates:

https://www.agric.wa.gov.au/spring/challenges-growing-hass-avocado-cool-regions?nopaging=1

This one has better detailed photos of flowers, to help you with hand pollination:

https://www.agric.wa.gov.au/spring/growing-avocados-flowering-pollination-and-fruit-set?nopaging=1

Well ill just call them the "wayne" cultivar my dad and I have the same middle name and he actually started the seeds haha. The two trees we have were actually started about a year apart or so and one of them just flowered for the first time this last spring but only had a few flowers. The other tree was pumping them out and even got fruit about the size of marbles, but fell off. It was started 2015 for sure the other may have been 2016-2018 we had the whole tropical fruit orchard growing in 30gal grow bags by 2019-2020 before planting them in the greenhouse floor fall of 2021.  

I may try the hand pollination this spring after reading those articles for the details. Are there any pollinators for avocados that can be mail ordered? I get bugs from naturesgoodguys for pest control. Maybe I need to start greenhouse bee keeping as well haha.

I wouldn't think the temp at that time would be an issue. January-February is our coldest months. And our greenhouse is kept above 50° for the most part, it might dip to as low as 40°-45° for about 3 hours in the early morning. And gets as warm as 90° on a warm sunny day during the winter with no heat and the door closed. We usually open the door cuz the humidity goes way up when it's sunny and the greenhouse reaches about 85°. So we have a decent temp and humidity Flux. The Temps, 40°(WINTER LOW)-105°(SUMMER HEAT) humidity, 25%(LOW when outside is below freezeing and we are burning a fire inside)- 95% (HIGH when it's warm and sunny outside and the greenhouse gets to 85°+ and doors closed).
So we have quite the fluctuations of climate threw-out the seasons.
We do have a IBC tote inside with a drip line for irrigating every 2weeks or so. We have deep mulch so the soil stays moist all the time not wet tho. So that's why we don't irrigate more. Unless we are having a drought or really warm then we water a bit more. I'll be sure to water more frequent when the trees are flowering. I assume all fruit is this way. We did just get our first jackfruit with fruit inside the other day. It was delicious. It wasn't a 30lb'er or anything but it feed 3 adults for a nice healthy snack I should have weighed it before and after cleaning it. Next time.....

So if our jackfruit trees can produce the rest should be OK. I think the most tender tree we have growing is the mango tree. Our other 2 died this one is the lone survivor. It's closer to the wood stove so maybe that's it. We also harvested our second homegrown pineapple this year. This one was planted in the ground and got much bigger then the first one grown in a 10gallon grow bag. It was delicious as well. We let it ripen to yellow/golden orange on the plant then cut it and ate it, OMG the best tasting pineapple I've ever sunk my teeth into. I don't even like eating pineapple from the store anymore. I'm a pineapple snob now. So I gotta grow my own haha.

michael rowald wrote:
might dip to as low as 40°-45° for about 3 hours in the early morning

That might prove fatal to effective pollination if that happens while they are flowering. From one of those links:

There is some suggestion that two to three consecutive days of minimum temperatures above 10°C [50°F], combined with day temperatures above 16°C [61°F], are required to achieve effective pollination.

I appreciate this thread, because according to the internet the best I'll ever have here is indoor houseplants that won't fruit if I plant avacados.  I think tropical fruit trees are hard to grow here.  A coffeeshop not super far away from my dad had a happy banana tree, it wasn't producing bananas yet, but it was tall, like 8 ft. and happy, had lasted a few winters, ... until we had a big snowstorm in Feb. of 2014, at which point it unceremoniously died a thorough death.  So even if something grows for 3 or 4 years one big snowstorm can destroy it, if its in the ground that is.  I think good things could be done in a greenhouse though, but the question is how tall does an avacado tree, or any other tropical tree for that matter, have to be before it fruits?  Because most yard greenhouses are only so tall.

If you can create a breed that handles the weather here cudos to you!!!  And we just may have to join your collective to obtain one once things are happening through some bad winters and still growing.

Riona Abhainn wrote:  So even if something grows for 3 or 4 years one big snowstorm can destroy it, if its in the ground that is.  I think good things could be done in a greenhouse though, but the question is how tall does an avacado tree, or any other tropical tree for that matter, have to be before it fruits?  Because most yard greenhouses are only so tall.

I hear you. A lady I knew was growing a bunch of "marginal" tree species and lost them all a couple of winters back.

Unfortunately, trying is extremely tempting, as many of these same fruits are either shipped huge distances or grown under questionable circumstances or both.

I'd suggest you visit this website: https://www.fruittreesandmore.com/
Scroll down to Bob's videos and have a look at how he encourages people to create micro climates that can be protected during those bad years. He's been in the business for decades, so he's experienced some of the weather extremes that took out your dad's banana tree. When you compare the energy required to ship fruit, having to add a little extra heat for the few days or weeks required in edge climates, is an acceptable trade-off to me, but until I can design the location from scratch for the marginal trees I want, I am limiting my experiments to starting things from seeds I collect from fruit - no cost experimentation!

Riona Abhainn wrote:I appreciate this thread, because according to the internet the best I'll ever have here is indoor houseplants that won't fruit if I plant avacados.  I think tropical fruit trees are hard to grow here.  A coffeeshop not super far away from my dad had a happy banana tree, it wasn't producing bananas yet, but it was tall, like 8 ft. and happy, had lasted a few winters, ... until we had a big snowstorm in Feb. of 2014, at which point it unceremoniously died a thorough death.  So even if something grows for 3 or 4 years one big snowstorm can destroy it, if its in the ground that is.  I think good things could be done in a greenhouse though, but the question is how tall does an avacado tree, or any other tropical tree for that matter, have to be before it fruits?  Because most yard greenhouses are only so tall.

If you can create a breed that handles the weather here cudos to you!!!  And we just may have to join your collective to obtain one once things are happening through some bad winters and still growing.

I think the Portland area is going to be more challenging than the Seattle area for avocados, unfortunately, but we do have over a dozen members in that area already, including some who got their first trees already this year, so the data is beginning at least. It just gets a few degrees colder there in those bad winter storms, and those few degrees may be right at the kill threshold.

The last two winters were pretty cold here, and while most of the little trees died, some came through great, or bounced back quickly. While it does occasionally get slightly below 16°F (my coldest temperature since starting this project), it doesn't get *much* below that. Hasn't gone below 14°F in over 30 years here, but it still could probably happen. Less likely with each passing year, though, as this area is warming faster than much of the continent.

Here's an example of a promising seedling that survived the 17°F last winter without any heated protection (just an upside-down flower pot), when it was barely a year from seed:
Tree #149 profile

So far no leaf damage even this year, which has definitely been milder.

I too had been planning to do some avocado breeding in the Willamette Valley, but have not had the resources. Wanted to get one of each of the names varieties with known cold resistance and stick them in the green house where I can protect them from the colder cold snaps and then plant out the crosses as I start getting seeds. But a time and energy commitment that I haven't been able to make. Excited to hear about this project!

Riona, the cold hardy bananas that are commonly sold and grown here are ornamentals. There are too common species/varieties that I've seen. They won't produce fruit in our climate, and even if they could, it would be more seeds than fruit. BUT, I did see someone successfully grow bananas in zone 8 elsewhere in the country. Being tropical, they need in excess of a year of growth to produce fruit. Which is basically just another way of saying that it needs to achieve a larger size than it can in a single season. This persons solution? Build a cage around the bananas and stuff it with mulch to insulate it so it doesn't die back excessively. Then, the following season, it can resume growing from where it left off and actually produce fruit. Haven't had the resources to experiment with that either, but it's on my never ending list...

Days like today make dreams of avocados here seem foolhardy. The low in my yard this morning was 14.7°F (-9.6°C) and the high today is forecast to be 24°F (-4.4°C). By the end of this freeze this coming Tuesday, it will likely have been below freezing for more than 100 hours straight, with most of that in the "hard freeze" range.

I just wish I could get a year or two without this kind of freeze. I'm sure larger trees could have a fighting chance, but I don't expect many survivors this time around, other than the three trees that I put light bulbs or heat lamps under their fleece. Other than those in the greenhouse, of course. The heater has kept that a bit above freezing and as long as we don't lose power that'll be ok.

Winn Sawyer wrote:Days like today make dreams of avocados here seem foolhardy.

I've been having similar thoughts. Averages mean nothing, when it's extremes that shatter dreams. I'm not even going to guarantee that the peach tree, roughly  espaliered against the west wall of our garage, will make it through this years' cold. But the records clearly show this in not something that hasn't happened before. (1950 recorded -13.3C)

I've looked at the articles about the Russian attempt to move citrus growing northward, particularly their trench systems. Have you contemplated that approach with avocados? There's a fine line between using the ground to moderate temperature, and creating a cold trap. I'm not sure how they balanced those concerns.

I've been away at my sister's and her local shop had a great deal on avocados grown in Mexico. I brought back 5 seeds thinking I'd look up the best way to start them. Do you know how long the seeds would be good for?

Jay Angler wrote:
I've looked at the articles about the Russian attempt to move citrus growing northward, particularly their trench systems. Have you contemplated that approach with avocados? There's a fine line between using the ground to moderate temperature, and creating a cold trap. I'm not sure how they balanced those concerns.

I think a trench is unnecessary, just a hoophouse with the ability to add emergency heaters would be plenty sufficient. But also, I'm fairly certain that we can manage to breed avocados that could survive these kind of freezes once they reach a mature size. Getting them to a mature size will just require a few mild years in a row.

But that's the rub, we have had lows in the teens all three years since I started this project! During the last few decades there were many 4-5 year stretches without that kind of freeze, and I was hoping to get lucky and have one of those stretches. Maybe soon!

I've been away at my sister's and her local shop had a great deal on avocados grown in Mexico. I brought back 5 seeds thinking I'd look up the best way to start them. Do you know how long the seeds would be good for?

As long as you don't allow them to dry out or get moldy, they will start sprouting at room temperature within a few weeks. If you refrigerate in high humidity they can keep for months.

I mostly germinate them by placing them on takeout containers with soil in them, on heating pads, and then transplant to Steuwe "treepots" or "deepots" once they crack open and the taproot starts to emerge. Like this:

Like Winn we're in an abnormal freeze here, Winn's daytime high was higher than ours, ours here in my little city was 18 degrees, tonight it will be a low of 12, the lowest in living memory of my whole life living here.  I hear tell that when I was tiny, maybe 2? it got colder, but that isn't substantiated because my parents don't really remember, so its a personal record for me.  Brrrrrrr.

My game plan for avacados is to plant some pits indoors, and when the warm times come each year I will take it outside and when the cold times come I'll bring it inside, or into a greenhouse if one becomes available.  I'll keep them in big pots so I can move them to the warmness inside in the winter.  Is it possible that, doing this, they could ever fruit?  I don't really want to do it if they for sure won't.

Riona Abhainn wrote:My game plan for avacados is to plant some pits indoors, and when the warm times come each year I will take it outside and when the cold times come I'll bring it inside, or into a greenhouse if one becomes available.  I'll keep them in big pots so I can move them to the warmness inside in the winter.  Is it possible that, doing this, they could ever fruit?  I don't really want to do it if they for sure won't.

You should plan to graft them if you want any hope of fruit that way. Seed grown trees rarely reach a fruiting size in a container. It varies from seedling to seedling, but typically they don't flower until they reach mature tree size, at least 10 but often more like 15 feet tall, and usually almost as wide.

Grafted trees start to flower right away, but fruit set in avocado can be as low as 0.001% of all flowers, and never is more than a fraction of a percent. This excerpt from The Avocado: Botany, Production, and Uses puts the maximum at 0.23%, so fewer than one out of every 400 flowers.


But at 0.001%, which is the lower end, you'd need more than 100,000 individual flowers to get a single fruit. Avocado flower clusters are pretty dense, but even still it would take a pretty large container to grow a tree capable of producing hundreds of thousands of flowers.

Last year, the trees in my greenhouse had probably 1000 flowers in total among the half dozen grafts, but zero fruit set. I'm expecting up to 10x as many flowers this year, based on how much larger the trees are (three trees each about 9' tall and 7' wide, and a few smaller trees with flower buds). I'm hoping for some fruit to set, but only time will tell!

That's such a bummer, my best friend, who lives in FL, has a tree that produces several fruits a year and its not even that big.  Maybe if I got a pit from one of her avacados it would produce likewise, high yield?  The info you share is depressing and makes me wonder how avacados are capable of being grown in bulk at all.
((

Riona Abhainn wrote:That's such a bummer, my best friend, who lives in FL, has a tree that produces several fruits a year and its not even that big.  Maybe if I got a pit from one of her avacados it would produce likewise, high yield?  The info you share is depressing and makes me wonder how avacados are capable of being grown in bulk at all.
((

Your friend probably has a grafted tree, and lives somewhere that the pollinators will bring pollen from other nearby trees? Like I said, grafted trees start to flower immediately. A grafted tree that is only 6' tall and 8' wide with a good pollenizer nearby can probably produce at least 10,000 flowers, which based on the excerpt above could result in around two dozen fruit (0.23% of 10,000 would be 23 fruit).

Smaller trees need pollenizers more, though, because the unique flowering pattern makes them less likely to self-pollinate than large trees. Large trees end up getting covered in their own pollen sufficiently set fruit without a complementary flowering partner, but small trees struggle with that.

The way avocados are grown commercially is in large orchards full of large (up to 30 ft tall x 30 ft wide) trees. Each tree that size has well over a million flowers on it, and typically those trees each produce a few hundred fruit.

There is a high density method used some, especially in South America, with trees aggressively pruned to about 10' x 10' instead of 30' x 30'. Because you can fit nine smaller trees in the same space as one normal tree, you can still produce at least as much fruit per acre that way even if each of those 10' trees only has a couple dozen fruit on them. They are also easier to harvest than the full sized trees.

Winn thank you for helping me learn more and giving me realistic expectations.

Riona Abhainn wrote:Winn thank you for helping me learn more and giving me realistic expectations.

Speaking of realistic expectations, I was expecting that all my trees were very very dead after our recent freezing weather. Here are the daily lows for each day since the start of the freeze, from my outdoor sensor:

January 11: 27.1°F

January 12: 18.0°F

January 13: 14.7°F

January 14: 17.2°F

January 15: 20.2°F

January 16: 20.5°F

January 17: 32.1°F

Those are the lowest temperature recorded on each date, which occurred in the early morning on most of the days, but not all of them (the first two days were coldest just before midnight). Here's the full temperature chart for the freeze, from the 11th to today, to show the highs as well:


And back to my expectations... they were mostly correct. It's too soon to be sure about which parts will die vs regrow, but even the trees covered in fleece mostly look like this today, which I think will be total death above ground:



But hey, every dead in-ground tree is another place I can plant a new one!

Just got home with these guys. Thanks so much, sorry I couldn’t stay to see the greenhouse.

Well according to the internet generally speaking avacados like zone 9 through 11, so I don't know if we'll evver succede, but maybe.  I heard that the way people were able to get lemons and limes that are hearty enough for zone 8 was to just grow them a little farther north each time, and eventually they expaneded their heartiness.  So if it can be done with certain types of citris then maybe someday?

Riona Abhainn wrote: I heard that the way people were able to get lemons and limes that are hearty enough for zone 8 was to just grow them a little farther north each time, and eventually they expaneded their heartiness.  So if it can be done with certain types of citris then maybe someday?

I read an interesting book about how plants learn - you want them to tolerate drought? Let them experience and survive drought! There is a trade-off though. The trees that experienced drought learned to grow more slowly and carefully, so they could live more easily with limited water. I find that many humans are impatient and want the tree to grow *now* and produce fruit *now*, so maybe as a species we need to return to times and ways of patience?

However, some of that impatience is real - if we're counting on our land to feed us, waiting until "next year" could leave us short on calories. This is where permaculture is so important, as it combines short term and long term goals through concepts like Restoration Agriculture and Syntropic Agriculture where systems are designed to build soil, feed the people and create long-term useful tree crops.

Right now, Winn and others are trying to extend the range of avocados. Eventually, if they're successful, those plants will hopefully become part of tree guilds helping to produce sustainable food. The healthy nature of the fat in avocados could be an important dietary addition here in the PNW.

I'm trying my little bit, but alas, my 2 avocado seeds do not seem to show any interest in germinating... Even if they did, there's only a remote chance they would be cold tolerant. But who knows?

Well my four pits didn't germinate either, clearly Alexa doesn't understand how to germinate avacados.  I guess I could try another method I read about online.  But I would want them to eventually produce, not just be pretty plants.  My father told me today that when he was a kid, my grandmother would germinate the pits all the time and grow them as houseplants, even though she had no intention of them producing fruit, they reminded her of her girlhood down in CA.

Riona Abhainn wrote:Well my four pits didn't germinate either, clearly Alexa doesn't understand how to germinate avacados.  I guess I could try another method I read about online.  But I would want them to eventually produce, not just be pretty plants.  My father told me today that when he was a kid, my grandmother would germinate the pits all the time and grow them as houseplants, even though she had no intention of them producing fruit, they reminded her of her girlhood down in CA.

There are many possible ways to successfully germinate avocado seeds. Most people start them in water, but I find their roots are happier if they go into soil right away. The method I use for the hundreds of seeds I start each year is adapted from the one described in the old UC publication Propagating Avocados:

https://anrcatalog.ucanr.edu/Details.aspx?itemNo=21461

Here's how that publication describes seed germination:

Seeds can be germinated acceptably in sawdust or sand, with careful attention
to optimum moisture maintenance. This is easier with newer materials such as
vermiculite or a perlite-peat moss mixture (figs. 9 and 10). At the University of
California at Riverside, we use UC #2 soil mix, which gives a good balance of
adequate drainage and adequate water retention, based on 1/2 sand, 1/4 peat moss,
and 1/4 nitrogenated redwood compost, plus added nutrients. All ingredients are
sterilized with steam or methyl bromide. Seedlings that show beginning healthy
development of both shoot and root can be transplanted into a suitable soil mixture
in the final, large containers for grafting. Instead of using a seedbed, nurseries now
commonly plant the seeds in plastic liners or seedbags, about 2 1/2 by 9 inches (fig.
11), with perforated bases for drainage.

What I do (with nearly 100% success) is lay out the seeds in takeout trays filled with a mixture of aged compost, soil, perlite, and sand, covered with lids, watered occasionally, and placed over a heating pad until the seeds begin to crack open, and then place them in their starter pots before the taproots emerge enough to become damaged by transplanting. There are photos above in this thread from January 13 that show what I mean.

Winn Sawyer wrote:

Here's what those seeds from the photo above look like today (photo attached).

While I think I'm done trying with avacados for now, I will eagerly watch your progress in creating a zone 8 viable variety and then I'll buy some from you in the future.

Riona Abhainn wrote:While I think I'm done trying with avacados for now, I will eagerly watch your progress in creating a zone 8 viable variety and then I'll buy some from you in the future.

I personally have no intention or desire to ever sell the trees produced by this project, but my hope is that the project does become democratically self-governed over time, so it's possible the membership will decide to do that at some point. I would much prefer if we continue to distribute the trees freely, as I've done so far. Trees for all!

In addition to the two trees I got from Winn, I’ve grown this avocado from a grocery store seed. I had about ten seedlings at the beginning of winter and most did not survive. We had a long cold stretch of below 15 degree days. I had put some of the seedlings in my garage and some ina cold frame. This was still the only survivor. It died back but grew new leaves in the spring. Anything I can do to make it less leggy?

I love that Winn!  Sharing is caring.  I do want to keep an eye on your progress.

Hi everyone!

Due to starting a few more seedlings than I'll be able to pot up for 2025 distribution, I've begun distributing larger numbers of smaller trees in the last few weeks. If there's anyone who's thought about joining the project, especially if you're willing to plant a large number of seedlings in the ground, please reach out!  Especially anyone in the immediate Seattle area, or within a couple hours drive of Seattle. Here's the page that summarizes what your membership will entail (ignore the part about 2024 distribution being finished):

https://www.drymifolia.org/join.php

Here's an example of the type of planting I'm looking for, this row of about a dozen trees was planted at a member's place a few weeks ago:

Cool tidbit from a book I've been reading!
The book quotes Doug Pow in Australia:
"Avocado trees come from a volcanic andosol, extremely new soil derived from volcanic ash, different from any soil in the world," he said. "We are trying to chemically get the soil similar to that which they evolved in, and biochar assists that."
"At 5% biochar the leaf area has doubled."

From: Burn Using Fire to Cool the Earth by Albert Bates and Kathleen Draper Pgs 111-112 There are a few more details

A friend of mine started a whole pile of Avocados growing in a raised bed she had veggies growing it. I just spent the afternoon transplanting over 20 babies into #10 pots. Many of them had taproots at least 6" long. It was a shame to have to bend them. This is why it can be so much better to start tree seeds right in their forever homes, but it is just too hard to give them any protection that way. Not sure what this winter will be like, but I will do my best to keep them alive!

Jay Angler wrote:Cool tidbit from a book I've been reading!
The book quotes Doug Pow in Australia:
"Avocado trees come from a volcanic andosol, extremely new soil derived from volcanic ash, different from any soil in the world," he said. "We are trying to chemically get the soil similar to that which they evolved in, and biochar assists that."
"At 5% biochar the leaf area has doubled."

From: Burn Using Fire to Cool the Earth by Albert Bates and Kathleen Draper Pgs 111-112 There are a few more details

I'd be curious to see the source for that claim about the soil where avocados evolved. Most of the papers I've read on that topic proposed that the Mexican highlands around Nuevo Leon are the original location of the species before it was domesticated many thousands of years ago. According to the attached soil map of Mexico, that area (which I've circled in red) is not listed as volcanic andosol.

A friend of mine started a whole pile of Avocados growing in a raised bed she had veggies growing it. I just spent the afternoon transplanting over 20 babies into #10 pots. Many of them had taproots at least 6" long. It was a shame to have to bend them. This is why it can be so much better to start tree seeds right in their forever homes, but it is just too hard to give them any protection that way. Not sure what this winter will be like, but I will do my best to keep them alive!

This is why I start mine in 14" deepots, and even in those the roots usually reach the bottom in a few months from sprouting. Starting them in their final location is definitely best if you plan to protect them with a heated cover for their first winter, but the problem with doing that is most Mexican race (hardier) types ripen from August to now in the northern hemisphere, and the seeds will likely not survive the winter outdoors in cold locations, and may only barely germinate before then, so they need to be started indoors. The other races of avocado ripen from late winter thru the summer, so those can at least be germinated before winter.

Bates' book does have a fair list of sources in the appendix, but I'm just not enough of a geologist to suggest where you would get better info. However, Doug Pow is growing in Australian soil, which could be considerably different from West Coast of America soil. Biochar may have made a significant difference in his ability to grow avocados, but that doesn't necessarily mean that the same will be true for your ecosystem or mine.

Have you ever tried adding biochar to your soil mix? If so, did you notice any benefit? I posted more as a possible  approach to improve our success rate, but gardening rarely offers guarantees. There's lots of garden advice out there that hasn't got a hope in my ecosystem!