Avocados and Frost in Europe (plus info on the cold-hardiest avocados and how to grow them)

Inge Leonora-den Ouden wrote: I noticed that the avocado plant doesn't like changes. One of those changes can be repotting. It reacts by dropping leaves. That's the most important reason why my avocado plant stays in my living room ... I fear it will drop leaves if I put it out, even on a nice summer day.

 

If an avocado tree can grow so big (and even fruit!) in London, then maybe it will grow here in the Netherlands too. The climate is about the same.
I have a new small avocado seedling now here, grown last year. The larger avocado will remain my houseplant, but with this second one I can experiment and plant it in the garden

I was just looking at one of your earlier posts, and noticed your above observation (the first quote), accompanying a picture of your potted indoor avocado plant.

Response to 1st quote above:
I've found that avocados hate any kind of root disturbance.  After transplanting, there always appears to be a period of several weeks before the roots re- establish themselves and then shoot growth recommences.  Unlike the fig plant, they dislike root restriction, which is why they never seem to thrive in pots in the long-term. Potted avocado plants often have their foliage on the upper part of the shoot, looking spindly, with long stretches of lower stem devoid of any leaves (e.g. your photo & Priyanshu's), instead of being 'bushy', and the shoots often show browning at the leaf tips (e.g. Priyanshu's photo). These symptoms are likely due to dry indoor air, exacerbated by central-heating in winter, inadequate light levels indoors, the evaporative concentration of salts within the potting compost, root restriction generally, or any combination of these environmental stress factors.  

Response to 2nd quote above:
If your local climate is favorable, avocados do best planted in the ground outdoors, where the relatively shallow root system can grow unrestricted,  spreading sideways out as far as the dripline. However, they need protecting from even very mild freezing temperatures i.e. down to −2°C, during the first 3 years. After the 3-year-old stage, avocados, grown from shop bought fruit such as 'Hass', should survive a brief freeze down to −4°C, though there will always be some frost-damage on at least the younger leaves and some of the older ones too; the buds seem more cold-tolerant.  If you do plant outdoors, make sure the location is sheltered from winds. A combination of strong winds, freezing temperatures and cold wet soils, all acting together, can be lethal.  Plant on a mound, ridge or slope for good drainage around the roots - particularly important in the winter months when precipitation is high.

Hope this helps.  

Mike Guye wrote:.....

Response to 2nd quote above:
If your local climate is favorable, avocados do best planted in the ground outdoors, where the relatively shallow root system can grow unrestricted,  spreading sideways out as far as the dripline. However, they need protecting from even very mild freezing temperatures i.e. down to −2°C, during the first 3 years. After the 3-year-old stage, avocados, grown from shop bought fruit such as 'Hass', should survive a brief freeze down to −4°C, though there will always be some frost-damage on at least the younger leaves and some of the older ones too; the buds seem more cold-tolerant.  If you do plant outdoors, make sure the location is sheltered from winds. A combination of strong winds, freezing temperatures and cold wet soils, all acting together, can be lethal.  Plant on a mound, ridge or slope for good drainage around the roots - particularly important in the winter months when precipitation is high.

Hope this helps.  

Thank you for the advice Mike. Ik will keep it in mind. Especially that mound and drainage.
The spot where I want to plant the experimental avocado is fairly warm and protected. It's about 2 meters from the wall of the house on which sun shines during a large part of the day (from early morning to halfway afternoon ... if it's sunny). There's a liguster hedge along the North(ish) side. Freezing temperatures below −4°C are very rare here.

Inge Leonora-den Ouden wrote:
The spot ... is fairly warm and protected ... about 2 meters from the wall of the house on which sun shines during a large part of the day (from early morning to halfway afternoon ... if it's sunny). There's a liguster hedge along the North(ish) side. Freezing temperatures below −4°C are very rare here.

It sounds like you've got a really nice sheltered spot.
Just one thing ...
If the privet hedge (Ligustrum) is close to the avocado tree (e.g. within 2-3 metres), make sure it [privet] doesn't go dry in the summer.  I say that because, unlike avocado, privet is very drought tolerant and, under summer-drought conditions,  its root system may invade the avocado's root space, competing for water. Avocado needs to be well watered in summer and its likely it's roots wont be able to compete successfully with the privet's more aggressive root system. Make sure you mulch the avocado to help maintain a fairly constant soil moisture level.  Before you plant the avocado outdoors to its permanent position, adapt it gradually to outdoor light for say 2-3 weeks - start with total shade, progressively exposing it to more sunlight as time goes on. This will avoid sun-scorch to the leaves, which have become accustomed to low light-levels indoors.  Do this when all risk of frost has passed, not before. Good luck Inge.

Mike Guye - you are so knowledgeable and generous with your experience. As a  mostly-just-wishing- to grow avocado fan l am impressed. And glad you’re on Permies

Damn that avocado tree in London is a beast. I reckon that it must have been a great experience to see them Mike ! Does anyone have links online to buy avocado seeds (Mexicola, Fantastic or Brogden) for shipping to France ? It will be awesome to test them. I can't find them here in Paris.
PS : I am aware that avocados do not reproduce true to seed. Would love to give it a try though regarding cold hardiness.

I’d been hopeful, poking in here, that someone had managed to grow avocados a little colder than in the teens, F° / -3 C. Given that I’m staring out the window at 0°F today, alas, I think they are still not meant for my property (front range Colorado).

Whoever’s lucky enough to have those Reed avocados, I envy you and wish you the best of luck with them. They are the best, most delicious, most enormous things, and I got them regularly when I lived in SoCal.

Are these flower or leaf clusters ? Never saw them like that before !

Priyanshu Uniyal wrote:Are these flower or leaf clusters ? Never saw them like that before !

They are definitely clusters of flower buds. Did these appear on one of your grafts & can you post a photo of the whole plant? I'm curious to see how big/old the whole plant is...

Yes they are on one of my grafted plant which was done exactly a year ago. The Scion grafted is from a mature tree. Here are the photos. I have put a water bottle to give you an idea regarding scale. It's a small plant.

Congratulations Priyanshu! You have flowers coming! Please send us photos to show what happens next.

Priyanshu Uniyal wrote:Damn that avocado tree in London is a beast. I reckon that it must have been a great experience to see them Mike ! Does anyone have links online to buy avocado seeds (Mexicola, Fantastic or Brogden) for shipping to France ? It will be awesome to test them. I can't find them here in Paris.
PS : I am aware that avocados do not reproduce true to seed. Would love to give it a try though regarding cold hardiness.

Yes, it was quite a surreal experience seeing that fruiting avocado tree in London - understandably, it did make me smile at the time!

I'm afraid though, I'm unable to help you with the location of a reliable source of Mexican avocado seed, i.e. authentic Mexican seed and not a store-bought substitute masquerading as 'Mexican seed'.

In this respect, be aware of  this fraud, so that you or anyone else doesn't get scammed by unscrupulous ebay sellers - especially these two:
(1) the New-York based ebay-seller, dausername1: he sold/sells fake Mexican seed as the seedlings I grew on, from the seed he supplied me, failed the crushed-leaf test. I did inform Ebay, though I think he may still be selling so-called 'Mexican seed'.
(2) London (UK) based ebay-seller, organicbio: I didn't buy from him but he told me a few porkies, which set the alarm bells ringing. He said he was selling Mexican seed, harvested from fruiting trees in his backgarden in London.  Subsequently, a few months later, by which time he's probably forgotten what he'd previously told me, I had another conversation. This time, when I asked him for some leaf material to carry out the 'crushed leaf test' he changed his story. This time he said he had never grown fruiting avocado trees in his garden, but imported the so-called 'Mexican seed' from abroad so didn't have any leaf material to offer me.

Draw your own conclusions...

It makes me very angry and sad at the same time, when people purposefully take advantage of others with their dishonesty.

I picked up 11 bacon avocados the other day . Can barter/share some of these with U.K peeps. If you are interested PM me.

I live in Ohio USA, zone 6 meaning that we can (but never in the 25 years since I've lived here) get down to negative 5 F. I experimented with 5 seed grown lemon trees. They for almost a year and then I accidentally left all 5 out in 19 F temps. All but one died.

The one that survived didn't even take a hit. It is perfectly healthy in every way. I have heard that plants can be acclimated to weather in a similar way that people can be. I will be taking cuttings from my surviving lemon.

My suggestion: Go for it. Try the avocado. After all, you will never know until you try. If they don't make it, try again. I would have never found my surviving lemon tree if I didn't take the chance (and make the mistake of leaving it out!)

Lemon trees will survive outside down to close to freezing weather. I leave mine outside until the temp drops to a killing temperature, then I bring it inside. I have hardened this tree off enough, that it has survived 32 F temps several times. Wish I could post a picture of it. It is super healthy.

Good luck to you! Go for it!

Joy

David Livingston wrote:http://www.gardeningknowhow.com/edible/fruits/avocado/cold-tolerant-avocado-trees.htm
I have reading the above and it gives me hope of growing one of these here in Norther (ish ) France . Anyone else tried this in similar climes and anyone any idea where I could buy one of the named types here in europe ?

David

Priyanshu Uniyal wrote:The Scion grafted is from a mature tree. Here are the photos.

Was the scion material delivered to you by post or courier, or was this taken directly from a mature fruiting tree, growing near you outdoors in France?  
If it was delivered to you, do you know how long it took between posting & arrival?
The reason for asking is that I'm curious to know if scion material is capable of surviving the delivery route.  

Henry Jabel wrote:I picked up 11 bacon avocados the other day .

Great news Henry!
Which supermarket chain did you buy these from?
I'm guessing they've been imported from Spain - is that correct?

Inge Leonora-den Ouden wrote:Congratulations Priyanshu! You have flowers coming! Please send us photos to show what happens next.

Thanks Inge Leonora-den Ouden. I might remove those flowers to promote root growth as it is a small plant and it will be beneficial for long term. Though it is really painful to drop those flowers. Maybe they will fall themselves... Didn't decide 100 % yet.

In this respect, be aware of  this fraud, so that you or anyone else doesn't get scammed by unscrupulous ebay sellers - especially these two:
(1) the New-York based ebay-seller, dausername1: ....
(2) London (UK) based ebay-seller, [u][i]or

Thanks Mike ! Yeah, It was tempting to buy from these sites in the past but I didn't go for them because I wasn't sure about the quality.

It makes me very angry and sad at the same time, when people purposefully take advantage of others with their dishonesty.

I understand, same here... In this world of internet, fake informations/declarations are everywhere. You are right to be very careful.

Mike Guye wrote:

Henry Jabel wrote:I picked up 11 bacon avocados the other day .

Great news Henry!
Which supermarket chain did you buy these from?
I'm guessing they've been imported from Spain - is that correct?

Yes they are indeed Spanish and were in a independent greengrocer. I am only finding hass in the supermarkets round here still.

Mike Guye wrote:

Priyanshu Uniyal wrote:The Scion grafted is from a mature tree. Here are the photos.

Was the scion material delivered to you by post or courier, or was this taken directly from a mature fruiting tree, growing near you outdoors in France?  
If it was delivered to you, do you know how long it took between posting & arrival?
The reason for asking is that I'm curious to know if scion material is capable of surviving the delivery route.  

I got it delivered by post. If I remember well, it came in a small cardboard box and scions were well moist inside a biodegradable bag that was rolled onto each of them very well. They came in a good condition and I didn't have any problem. The delivery time was long though. I think around 1 month. The guy responded well to all questions I asked. I didn't suceed in cuttings (I was a bit lazy as well) but grafted ones worked for me.

Priyanshu Uniyal wrote:I might remove those flowers to promote root growth as it is a small plant and it will be beneficial for long term. Though it is really painful to drop those flowers. Maybe they will fall themselves... Didn't decide 100 % yet.

I'm so excited for you! It's also interesting to see the 'proof' that grafted trees fruit earlier, which I had read elsewhere. I would be strongly tempted to at least let the flowers open and see if any do set, then remove all but one of the fruit (if you get any). I know that you shouldn't really but....
Good luck!

Priyanshu Uniyal wrote: I might remove those flowers to promote root growth as it is a small plant and it will be beneficial for long term. Though it is really painful to drop those flowers. Maybe they will fall themselves...

Yes, I agree with you about removing the flowers and your reason for doing this.  I understand your reticence, but don't worry, as it will probably flower every year as the scion is mature wood.

In the short-term flower-removal  is best, as the plant already looks very stressed, as evidenced by the brown leaves and small size. Bearing fruit would be an additional stress and I'm uncertain if it would survive. If I were you, after flower removal, repot it into a nice large pot so the roots can develop more (they hate root restriction). Plant it into a commercial potting compost, ideally one that includes loam. To lighten the mix, you could add some vermiculite. Alternatively, in late Spring you could plant it outdoors in a suitable spot, after the risk of frost has passed, adapting it slowly to the outdoor light levels.

When the scion is more developed, you taking cuttings from it and try and root them, though I'm sure you've already thought of that.

In the short-term flower-removal  is best, as the plant already looks very stressed, as evidenced by the brown leaves and small size. Bearing fruit would be an additional stress and I'm uncertain if it would survive. If I were you, after flower removal, repot it into a nice large pot so the roots can develop more (they hate root restriction). Plant it into a commercial potting compost, ideally one that includes loam. To lighten the mix, you could add some vermiculite...

Thanks Mike. Yes, I will soon repot it onto a larger container and remove those flowers. But I am bound to keep the plant in a pot as I have no garden, just a long narrow balcony (sigh...).

Yes, it is in stress but I don't think that it is a rootbound issue. New leaves don't have brown tips (Although, I agree that they are smaller in size). Infact, leaves turned brown only when it was really cold outside (-2 to -5). And the growth is steady. I think boiling water did the trick to get rid off the salt accumulation.
I tested rootbound issue in december by just sliding down the pot carefully (Was very scared to give my plant a shock at the same time as it was not easy). The roots were fairly far from the edges on all sides including the bottom area where I have covered drainage holes with pebbles. I brought it inside in late january and I am pretty happy the way it took the cold weather for 1st year. As the spring season is arriving soon, yes, repotting will be nice to promote overall healthy growth for coming spring n summer 2023.

When the scion is more developed, you taking cuttings from it and try and root them, though I'm sure you've already thought of that.

Yes, I am eagerly waiting for them to grow a bit more to lay out cloning tests.

Happy gardening !

Priyanshu Uniyal wrote:. I think boiling water did the trick to get rid off the salt accumulation.

Yikes! What was that exactly..

Yikes! What was that exactly..

I flushed the plant with water that was boiled and cooled off to a normal temperature before pouring.

Priyanshu Uniyal wrote:

Yikes! What was that exactly..

I flushed the plant with water that was boiled and cooled off to a normal temperature before pouring.

The minerals commonly found in tap water are calcium, magnesium, sodium, and phosphorus. Though their concentrations are low, they will increase over time in the substrate of pot-grown plants, unless they are regularly flushed-through.

If you boil the water for a long time, the dissolved salts/minerals will concentrate (not get less), due to evaporation of the water.  However, it's likely that boiling will significantly deplete the levels of dissolved gases such as oxygen and carbon-dioxide. Tap-water is often treated with chlorine (sometimes fluorine is used instead) to make it safe to drink, by killing harmful bacteria,  so levels of chlorine will also be depleted by boiling, though that's probably not a bad thing.

[edit 17/2/2023] - Degassing the irrigation water (through boiling), could be harmful to the plant by subjecting the roots to anoxic conditions, as it would be expected to contain significantly lower levels of dissolved oxygen.

The usual method of preventing salt build-up in pots, is to flush them with water - normally, this is done to run-off (i.e. until water comes out of the base of the pot).  However, based on the behaviour of gases (which is also a fluid), you would need the equivalent of three pot volumes of water to replace 95% of the water and minerals already in the pot. However, if you flush with water, you'll need to feed afterwards, as you'll presumably have leached out most of the mineral nutrition available for the plant. Alternatively, you could flush your pots with dilute fertilizer, though instead of pouring the leachate down the sink (which isn't good for the environment) you could use it to water plants in your garden.

Therefore, in conclusion, no benefit is gained by boiling your irrigation water - in fact it could be harmful.

The minerals commonly......  Therefore, in conclusion, no benefit is gained by boiling your irrigation water - in fact it could be harmful.

Thanks Mike, it's interesting to know about boiling water. I added an organic fertilizer to give something new to the plant after flushing. I guess that helped it not to loose necessary nutrients needed. Also, I removed all flowers finally... Was painful but leaves are growing fast now which is a good sign. There are no brown tips for the time being. I will repot the plant after winter holidays.

A quick video update from last year avocado graft to flower removal.

Hi guys,

This is a fascinating thread. I have recently moved to central Portugal and one of the first things we are doing with the land is planting trees... because they take so long to grow. Our property is in the mountains (Serra da Estrela) so it gets chilly in winter, nevertheless we are determined to grow avocados!

I have ordered three 'Mexicola' seeds from Mexico (got them from a seller on Etsy). It's a gamble - who knows what they will be and if they will even arrive! I intend to grow them in pots indoors and in a bright protected solarium for the first few years until they are ready to plant out.

I have also been given a rooted seed from family in Algarve, from an excellent tree (no idea of the type). We will also try planting this one eventually (although I may wait until it is quite large and protect it during its first few outdoor winters).

I have experience of growing avocado seedlings indoors in the UK in a conservatory that gets very cold. A few times they all dropped their leaves and 'died' in winter, only to come back full-force in spring, so I have faith in their determination to survive a cold-snap... unlike some other plants!

Hope to report back here in 13 years or so with three fruit-bearing Mexicola in the Portuguese mountains!

Rudyard Blake wrote:Hi guys,
I have ordered three 'Mexicola' seeds from Mexico (got them from a seller on Etsy). It's a gamble ...
Hope to report back here in 13 years or so with three fruit-bearing Mexicola in the Portuguese mountains!

Yes, it's always a gamble when you buy avocado seed off Etsy, Ebay, etc, because of fraudsters. I've had my fingers burnt twice when I thought the supplier had sold me Mexican seeds. I've already highlighted this earlier on, in this avocado thread.

When your seedlings have germinated, and you have enough leaf material, remember to carry out the crushed-leaf test to verify whether you have the authentic Mexican avocado type (scroll back for details on this). Knowing this will obviously save you wasting a lot of  time nurturing plants, in the case where you'd unfortunately received fake-Mexican material. Fingers crossed that you've got the real thing Rudyard  ...

Mike Guye wrote:

Rudyard Blake wrote:Hi guys,
I have ordered three 'Mexicola' seeds from Mexico (got them from a seller on Etsy). It's a gamble ...
Hope to report back here in 13 years or so with three fruit-bearing Mexicola in the Portuguese mountains!

Yes, it's always a gamble when you buy avocado seed off Etsy, Ebay, etc, because of fraudsters. I've had my fingers burnt twice when I thought the supplier had sold me Mexican seeds. I've already highlighted this earlier on, in this avocado thread.

When your seedlings have germinated, and you have enough leaf material, remember to carry out the crushed-leaf test to verify whether you have the authentic Mexican avocado type (scroll back for details on this). Knowing this will obviously save you wasting a lot of  time nurturing plants, in the case where you'd unfortunately received fake-Mexican material. Fingers crossed that you've got the real thing Rudyard  ...

I have hope because I have the tracking number and I can see that the seeds are indeed on their way from Mexico - who can say what kind of avos they will be turn out to be though.

I intend to carry out the crushed leaf test - yet another valuable gem of knowledge from this forum.

Inflorescences have developed for the first time on the 6-year-old 'Hass' tree (grown from seed) - May 2023.  I was surprised by this, given its young age, and that it hasn't been grafted. A total of three inflorescences were found. Curiously, they were all located on the same S/SW-facing lower branch.

However, winter damage has been severe - the 2022/23 winter has been the coldest in the life of this tree.

On the positive side,  it's normally quiescent dormant buds are springing into life, so it's expected that the tree will show good recovery. However, to aid recovery, any flowers setting fruit in 2023 will be  removed.

New photos & updated details have just been added at  https://imgur.com/a/5gflnlU
(winter temperature data will be added shortly)

My main blogs for growing avocados outdoors in southeastern England, U.K. (all grown from seed) have been recently updated (May/June 2023),
including temperature data for winter 2022/23:

'Del Rio': https://imgur.com/a/dAbixIe      10 months old
'Bacon': https://imgur.com/a/FmRvs7d     18 months old
'Fuerte': https://imgur.com/a/0XuODou      4 years old (total):  frost killed at 2 years old, then 2 years growth recovery
'Hass': https://imgur.com/a/5gflnlU             6 years old, flowering

The tree ages given above are for June 2023.

Mike Guye wrote:My main blogs for growing avocados outdoors in southeastern England, U.K. (all grown from seed) have been recently updated (May/June 2023),
including temperature data for winter 2022/23:

'Del Rio': https://imgur.com/a/dAbixIe      10 months old
'Bacon': https://imgur.com/a/FmRvs7d     18 months old
'Fuerte': https://imgur.com/a/0XuODou      4 years old (total):  frost killed at 2 years old, then 2 years growth recovery
'Hass': https://imgur.com/a/5gflnlU             6 years old, flowering

The tree ages given above are for June 2023.

I am very impressed with how your avocados have been doing, Mike. How did the flowers do on your Hass seedling? I would also like to know a little bit more about the winter protection you use. What type of horticultural fleece are you using? I have a roll of fleece that I got for protecting my Musa basjoo bananas the other year, but I don't think it's the thickest, so I wrap them in several layers. Also at what temperatures do you normally protect them?

Peter Entwistle wrote:
I am very impressed with how your avocados have been doing, Mike. How did the flowers do on your Hass seedling? I would also like to know a little bit more about the winter protection you use. What type of horticultural fleece are you using? ... Also at what temperatures do you normally protect them?

Hi Peter, detailed answers to your questions are contained in the Bacon & Fuerte links (re. winter protection) and the Hass link (re. flowers)  - for each you'll need to scroll down to the more recent posts. Do check these and if there is anything I've left out, do get back to me.  You might be interested to know that the U.K. publication Kitchen Garden magazine have commissioned me to write a feature article for one of their 2024 issues, on growing avocados in the U.K ...

'Del Rio': https://imgur.com/a/dAbixIe      1 tree
'Bacon': https://imgur.com/a/FmRvs7d     5 trees
'Fuerte': https://imgur.com/a/0XuODou    1 tree
'Hass': https://imgur.com/a/5gflnlU           1 tree

This year has been very good for my mini-orchard of young avocado trees. Hot June weather followed by a wet and humid July and then superb September weather, favoured vigorous growth for all trees.  The four links above are now updated, as of the 12 October 2023.  

Mike Guye wrote:'Del Rio': https://imgur.com/a/dAbixIe      1 tree
'Bacon': https://imgur.com/a/FmRvs7d     5 trees
'Fuerte': https://imgur.com/a/0XuODou    1 tree
'Hass': https://imgur.com/a/5gflnlU           1 tree

This year has been very good for my mini-orchard of young avocado trees. Hot June weather followed by a wet and humid July and then superb September weather, favoured vigorous growth for all trees.  The four links above are now updated, as of the 12 October 2023.  

Thanks again for your detailed posts, Mike. You've definitely inspired me to have a go with avocados. I've only ever grown them as houseplants as I was always worried about putting them outside, even in summer. I have a grafted bacon avocado, which I tried to grow in the greenhouse this year, but I brought it back inside recently as it kept getting eaten by snails and since it would be impossible to replace it I didn't want to risk it. It's not looking very healthy at the moment though. I was also quite fortunate to be sent some scions from a friend of one of the fruiting London avocado trees, which I've attempted to graft onto some Hass seedling plants. I just hope my grafts are successful now 🤞

Peter Entwistle wrote:
Thanks again for your detailed posts, Mike. You've definitely inspired me to have a go with avocados...

Thanks Peter, you're more than welcome. Shame about the slug/snail issues. It's good you've got a grafted Bacon (mine are all seed sown) - these are the best as they usually flower within a short time as the scion is  normally taken from a mature fruiting tree, instead of significantly longer time (if at all) for the seed sown ones.

Anyone living near to the St Leonards-on-Sea or Hastings area (U.K.), is more than welcome to drop in and see the avocado trees, though I can't promise you'll see any fruit ! If interested, just mail me to arrange a visit.

NB. EDIT 16 October
07:37 -  at first it looks like someone hacked my link for the 'Bacon' blog at https://imgur.com/a/FmRvs7d  , apparently posting 'adult images' on it.  
07:45 -  just clicked on the "I'm over 18" button at this link  to see what's going on - no 'adult images' appear to have been inserted, despite the misleading warning over adult content. I'm in contact with imgur about this & hope to get it sorted out a.s.a.p. Rest assured, you can visit this link and all you will see is pictures of  avocado plants.

Hi everyone! I finally decided to sign up for an account on here after Mike told me he's been posting updates on his avocados here.

I'm in the third year organizing a semi-decentralized cold-hardy avocado breeding project in Seattle, which has a similar "cool-to-cold mediterranean" climate to much of the UK and some parts of mainland Europe that have a strong maritime influence.

This coming winter will be the third one with avocado trees planted outside since I started the project, and I'm happy to share more information with anyone interested in our progress. The last two winters were both unusually cold for us (lowest temperatures were around minus 8° to 9°C both winters, when our winter low is more like -3.5°C to -5.5°C most winters), and many of the trees died.

This year was the first where I distributed a significant number of trees to project members (~30), and I also planted out many more trees this year since it is an El Niño, which for us typically means a very mild winter. I haven't gone around to do a headcount, so to speak, but I've got something like 40 trees planted out in my own yard, plus another ~50 in pots ready to be distributed next year. Most of the trees are seedlings of allegedly hardy cultivars, but some are grafted as well.

I've also got a greenhouse where I'm growing multi-graft trees that should finally start fruiting next year (they've been flowering for 2 years now but no fruit, and fruit set is notoriously low for small avocado trees, especially in cool climates). There are ~30 grafted varieties in the collection, but only a handful are large enough that I expect fruit next year: Duke, Jade, Aravaipa, Walter Hole, Joey. A few others may be large enough, but may not be, including Long South Gate, Poncho, Linh, and Brissago (ortet is a found tree growing in Brissago, Switzerland).

Mike will be the first to tell you that he doesn't approve of the cruel (to the trees) methods we've mostly been employing, where most trees get little or no protection over the winter. However, while a definite majority of all trees have died, some of the survivors continue to regrow vigorously from their frost-damaged stumps, and three of the trees that survived the 2021/2022 winter are among the healthiest at this point. Here's an example of one of those, #51, a seedling of Mexicola Grande (the images can be slow to load, so give it a moment, and the oldest are at the bottom):

https://www.drymifolia.org/photos/?view=51

I look forward to seeing updates on here from people in the UK and EU successfully zone pushing avocados! And for anyone living here in the Cascadian lowlands who wants to join the project, I've not been doing a great job with member logistics lately, but you can join on the website and I expect that I'll be doing tree distributions every year from here until I die!

Sorry for double-posting, but I'm finally reading through the entire thread and wanted to respond to this one:

Peg Campbell wrote:The biggest expert of this (among several others here) is Oliver Moore in Gainesville.  Not sure if he's on this Group but here's a post he did recently about Avocadoes.  I have a few from him that have survived freezes so far.  He is even colder and has plenty.  Besides growing the cold hardy he also has a greenhouse and multiple ideas for protection.
If you talk to him--invite him here if he isn't already.  I may do the same!

Oliver's place is great! I visited him in 2021 and got a few trees from him, including the "Jade" tree I planted in the greenhouse to hopefully be a seed source starting next year. It's about 9ft/3m tall now, next season I'm going to need to start pruning the top to keep it from hitting the ~4m apex of the greenhouse roof!

I doubt anyone in Europe would be able to import trees from Oliver, but there is one source of good scionwood in CA that is willing to provide all the necessary paperwork to import:

Fruitwood Nursery

It's not cheap, but if you can afford it, I do highly recommend them. They have a number of hardy varieties not usually available as mail order scionwood, and the cuttings are always of excellent quality. Their inventory gets updated every year in November, so everything is marked out of stock now but will be in stock soon.

One other thing that came up a few times in this thread was the issue of whether you can root avocados, or how to get a variety on its own roots. It is a very lengthy process that has only moderate success rates for most Mexican-type avocados (and very low chance for the other two botanical groups), but I've successfully rooted a growing number of cuttings. I've tried taking them at various times of year and found the last flush of autumn, cut just before the leaves finish expanding, has the highest success. I keep the 2-5 newest leaves and about 10 to 25 cm of bare stem with the buds removed from that part.

I usually first soak them in regularly changed water for at least a week and occasionally up to a month, but 10 days is pretty typical. This seems to help them callus more effectively so the stem doesn't rot, though some percentage do wilt in this stage and those should be discarded immediately so they don't foul up the water.

Next, they go in a starter pot in soil with a jar or plastic tub (preferably transparent or at least translucent) covering them to maintain humidity. I mostly use treepots or deepots for rooting cuttings, same as I use for germinating avocado seeds. The cover should be removed every day or two for at least 3 months, to allow air flow and to check soil moisture. I usually water about once or twice a week for that stage, and once again some will wilt and those should be discarded. These are usually either on or near a heating pad in the greenhouse all winter.

By late winter or early spring, I begin removing the humidity covers, and water less frequently but more deeply, to encourage root growth with a dry/wet cycle. Any that do not wilt at this time have a good chance of eventually rooting, but do not expect to see any new growth on the cutting for at least 5-7 months, and sometimes even 9+ months. The first flush will likely be feeble and fail to expand, and that's ok. Do not disturb the roots or attempt to repot them for at least a year, and not before at least one vigorous flush has occurred.

Here are some examples of successfully rooted avocados at various stages of the process, you can click on the film icon for each specimen to see other photos (and sorry some are rotated, fixing that is on my to-do list):

https://www.drymifolia.org/trees.php?subset=rooted

Of those, I'm most excited about the oldest clone I made of a named variety, this Aravaipa clone that went in the ground this summer, which is #218 (scroll down to see the roots when it was potted up earlier than I would recommend), here's the most recent photo on there, from a couple weeks ago:

We live in Cornwall (the most South and west point) in the uk/ England. So it's as mild as I think you get in the UK?

We put a polly tunnel up 3 and a half years ago. We weren't very prepared, most of the compost we used was out of our own compost bins, that happened to have quite a few hass avocado seeds in it. After a few months we noticed avocados sprouting. Unfortunately the majority was under the fig tree. We left our place for a year and a half, so the polly tunnel was left to re wild it's self.
We returned in summer, and found a avocard tree shooting up literally from the base of the fig. I had seen it before, but I wasn't expecting it to have survived. It had some major die back in the summer but then has had more growth. (Don't get it confused with the fig tree (which it's atached to) the avocado stem (that's mostly died off) is about an inch thick.

I guess my point is, if this guy (and others) have survived from seed in my polly tunnel (that had a missing door and several holes when we returned) then I'm sure more hardy verities could do well in climates that get a little frost.