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

I have a Hass from seed and a grafted Bacon, each 1m or so now and planted on a southeast-facing slope at 400m in the Serra do Açor. Not sure of the root stock of the Bacon, but I hear nurseries in Spain are using the Mexican cold-hardy rootstock and I'd be surprised if they weren't here too since avocados have only started appearing in the weekly markets in Central Portugal relatively recently. Fuerte is also available here, again, grafted. I have a friend living at 600m on the northwest-facing slopes of one of the highest mountains in the area who has about 30 avocados in various stages of development, including 2 flowering. I saw them just a couple of weeks ago. The largest is on the south-facing slope of a west-facing valley - nice little microclimate - but they get snow here in winter and it can be pretty bitingly cold. I know of several at lower elevations in the area.

As far as I'm aware, the more varieties you have in close proximity, the better for pollination. And some from each of the A and B groups is essential. A group varieties are receptive to pollen in the morning and shed pollen in the afternoon (ie. female flower is open in morning, male flower is open in the afternoon). B group varieties are receptive to pollen in the afternoon and shed pollen in the morning (ie. female flower is open in afternoon, male flower is open in the morning). Each sex of flower will open no longer than 12 hours. If the temperature is 17°C or lower, the female flower will not open at all and if the temperature drops below 17°C while the female flower is open, it will close.

This is way nitpicky, & I apologize, but the avocado variety is "Fuerte"= strong, not "Fuente"= fountain or spring. paz, Ricardo Valle

Rick Valley wrote:This is way nitpicky, & I apologize, but the avocado variety is "Fuerte"= strong, not "Fuente"= fountain or spring. paz, Ricardo Valle

My spelling goof. Thank you for the sort out.

Quick update.

All the seedlings that I kept in pots in the shade survived our summer.

All but one that I planted out died, and that one had some shade.  The bit that was taller than the shade died.  From now on, any avocado I plant outside will have three posts around it for me to wrap shade netting around.

The only seeds that germinate for me are from Spanish seeds, not from further afield - probably the others have been chilled and affected the germination.  So Spanish avocados only for me from now on, no matter how interesting the variety.

The first fruit trees of the season have just appeared in the shops and I did a tour of the whole town yesterday in search of varieties.  I found several Hass, one Bacon and one Reed, so I bought one of each home with me.  I've also asked if they can source a Fuerte for me.  I'm very hopeful!  Now I'm just waiting for the Spanish avocados to turn up in the supermarkets again so I can buy some more seedstock.

Any news after the cold days, did they survive, and if yes to which temperature?
I read on the french grafting forum that quite a few avocado trees live and produce in London, and some got a bit burned by the cold.

Lots of avocados (some from seed) grow around Hobart, Tasmania.. very similar climate to southern/south East England..
Should definitely be able to grow in protected areas.. plus there is a new-ish commercial avocado farm growing hectars of them in the north of Tasmania.. warm summers but pretty cold in the winter.. they do have awesome soil up there though.. the cooler temperatures means the fruit sit on the tree for longer.. but that creates a far richer, superior taste (apparently)

Hello,
i am trying to grow avocado outdoors in Brittany, France using stones to create a microclimate.
Other than choice of the right variety, creating a microclimate and hoping i don't see what else to do.
Having said that i was told recently about a biodynamic way to increase plants frost-hardiness using red valerian.
I have four avocado trees outside (still very small), three varieties in total.

These two avocadoes are "Mexicola". A variety that is said to withstand -6 Celsius (21 Fahrenheit) without damage. When it gets colder the leaves will be damaged and might fall off.
It then often resprouts the following spring if the cold wasn't too severe. I was lucky to get some Mexicola seeds. These two plants were started off from seed last winter indoors.
When you crush a leaf you get a strong anis smell. Apparently this is a characteristic of all mexican avocado varieties.

The second plant has a more reddish leaf colour. This happens when the plant struggles with cold températures, so maybe the first one is more cold-hardy?

This is a more recent picture of the first avocado seedling i planted with more stones in place. The stones are sitting on black plastic, which was not really what i wanted. My idea is to put a thick layer of sheeps wool under the stones.
But i didn't have sheeps wool back then and i was eager to start. The tip with the sheeps wool came from a friend of mine who made really nice rock gardens using sheep wool as a natural weed-suppressing mulch and heat insulation
(more heat gain per stone i reckon, cause the stone is insulated from the cold ground)
Sheep's wool takes years and years to break down and a rock garden designed this way creates a microclimate and remains weed-free for ages.

This little seedling already survived a winter outside, but i protected it really well.
I put 5 liter plastic bottles around it in a circle and some clear plastic over the top.
This worked really well.

The plant was grown from seed from a mother tree that is about 20 years old and fruits abundantly outdoors in Brittany.
It produces delicous fruit that look like Hass avocadoes and since the tree is all on its own it is self-fertile.
It does grow, however, in a small village near the coast of Brittany where the climate is much milder than where i live.

http://www.letelegramme.fr/local/finistere-nord/brest/lesneven/plouider/culture-francoise-deniaux-regarde-pousser-ses-avocats-14-07-2011-1370099.php

My last avocado plant is a grafted avocado i bought from tropicaflore.com.
It was very expensive. It cost 68 Euros including postage. In the description it is said to be able to handle -10 Celsius (14 Fahrenheit)

https://www.tropicaflore.com/fruitiers-exotiques/persea-americana-greffe-et-clone-duke7.html

I couldn't resist and i ordered it. It arrived in good condition but is now sort of standing there in"shock"!
No Wonder really cause their trees come from nurseries in thailand.
So i hope its great cold tolerance is true and that it will somehow manage to adapt and grow in cool central Brittany anyway.

As to the variety, i read in french forum that this tree is Hass grafted onto Duke 7 rootstock, so the text is very misleading.
When i searched the net for info on Duke 7 almost every site was referring to it as an avocado rootstock variety.
But as long as it will grow and hopefully make fruit one day far ahead in the future i don't really care what variety it is.

When i have some time to spare i should build rocks on wool around this one and the others too.
A stone wall would also be very good but that's too much of an effort.

Phillip, I like your idea of using the rocks as heat sinks...have you gone out on cold nights to compare the air temperature inside a cluster of rocks with the air outside the cluster.  If it making a difference, then as the tree grows up, you could pile rocks on top of rocks and have a rock greenhouse of sorts.  That would also have the side effect of keeping sun off the delicate avocado bark.  You'd just have to make sure the rock piles were stable, and that your area is earthquake proof.

You're on the right track with the Duke 7, but it's true that Duke 7 has been used as a rootstock for many years (less so now I believe).  The reason is that it has root rot resistance and is also graft compatible with commercial varieties.  They don't seem to be sold as fruit producing trees, at least I have never seen them mentioned in lists of cold hardy trees.  

There are some large Duke trees still growing in the Oroville, California area, and there are still some Duke trees remaining from part of an orchard in the Bangor, California area.  Apparently they still sell the fruit at local markets in the Oct/Nov period.

About 1 1/2 years ago I obtained some "Duke" seeds from two sources in the Sacramento, California area.  One source was from someone who thought he had gotten them from one of the original Duke trees, and the other source was from another local area person who had visited a large old Duke tree next to the old railroad station at Oroville and taken scionwood.  He had someone in his area graft this Duke scionwood onto rootstock grown from local (Waterford, Calif.) area cold hardy seeds.  One of his grafted Duke's grew a huge amount in two years and produced fruit...and he sent me 3 seeds from that fruit.  So I'm trying to grow Duke seedlings, from seeds from these two sources.  My climate isn't as cold as yours, but it's cold enough (24-28F each winter) that Hass and Fuerte are very marginal.  I have a grafted Fuerte, and some Fuerte seedlings, growing in contained outdoors and they've handled 28F(-2C) without any problem, but it doesn't stay that cold for many hours here.   Neither Hass or Fuerte are considered cold hardy varieties (and the list in one of the messages above is incorrect listing Fuerte above Mexicola as it's not even close in cold hardiness to Mexicola).

My Duke seedlings from the 2nd source died on me, probably from not watering them correctly in the hot summer weather here.  I have about 5 of the other source seedlings still in small containers and cups under grow lights indoors.

I hope this information is interesting to you, and although it would be surprising if your Duke 7 had a Duke grafted onto it, even if the graft is killed by cold weather it's worth it to let the rootstock keep growing.  I don't know what quality fruit it would produce, but it has the right genes for cold weather.

I'm attaching a pdf file from a 1963 California Avocado Society yearbook, some pages about the Duke avocado and it's origins.

Also, here's a link to a small northern california nursery that tests, grows and sells cold hardy varieties.  I've been wanting to buy a Bonnie Doon from them but they are a small nursery and often sold out.  http://www.epicenteravocados.com.  It's a good source of information.

John
Topanga, Calif.

great idea with the rocks am thinking of trying something similar with slate here in anjou

Did someone really test the cold-hardiness of Mexicola Avocado ?? Is it real what we read about ? I was also wondering when does it fruit (period) in temperate climate ? (Before Christmas ? or later? and are the fruit damaged by light frost ??) !!!

The last thing....i read it can take 15° and survive without damage....but if the temperature are higher, but last for a long period (For example 25° F each night for 1 or 2 weeks, with max temp of 40° F or less) does it withstand ??

Which are your experiences ??

Thanks

http://www.chestnuthilltreefarm.com/store/p/189-Mexicola-Avocado.aspx

Mexicola ripens in july/august according to this website.
I have researched avocados a lot but i don't have much first-hand experience yet.

I don't know if mexicola fruit can be damaged by light frost, but i would think yes.

One very important thing to understand is that the Young plants can handle NO FROST (or very little)
When they get older their frost tolerance increases.
So they have to be protected from frost for the first 3-4 years i reckon (maybe more)

Once the mexicola tree has a trunk with bark and is 2 to 3 meters tall i would imagine (and hope)
that it then can withstand up to -7 Celsius without damage.

And i think less cold but for longer periods shouldn't be a problem.

Also the soil should have good drainage and not be too wet.

I am worried for my own avocados right now cause i think i haven't protected them well enough
I will try and post pictures of the damage if i have the time.

Thanks....as I know Mexicola is one (or the) of most cold-hardy cultivars....so, if it will survive with no damage at -7°C it could be a very good choice for place where Mandarin tree survive..

I found someone selling Mexicola trees in Portugal!  

I've contacted him to place an order for two.  Will update when I've heard back and know more.

Big question is how much will they cost burra ? And to post to France ?

David

Woohoo - I have two mexicola plants booked!

I think the are in short supply though.  Here's a link to the facebook post he made - https://www.facebook.com/tristan.coverdale.7/posts/10156208168113622

And this is what he posted.  

We are very pleased to announce the arrival of the most frost resistant avocado tree in the World.

Coming soon......

A big welcome to the MEXICOLA AVOCADO!

These remarkable trees are able to withstand temperatures down to as low as -7 celcius vastly increasing the areas in Europe where avocados can successfully be grown. Temperatures of 40 c and above in Summer are no problems either.

They have the highest quality flesh with a high oil content. They are smaller than the avocados you will be used too, around the size of a plum with paper thin skins that are edible and have a delicious anise flavour. You'll need several fruit to make a bowl of guacamole! But with yields of 25 kg plus when mature you will have endless guacamole heaven!

Another wonderful and unusual feature of this tree is the edibility of it's leaves. Many varieties of avocados from other regions actually have toxic leaves but the Mexican avocado leaves have been traditionally used to flavour black bean dishes and many others. Like bay leaves the flavours concentrate upon drying. They give a flavour similar to anise with a tarragon fragrance and sometimes hints of hazelnuts.

The fruits ripen from late August through to late October when no other varieties are producing in Europe so you won't need to buy any imported fruit during this period.

We are starting a business this April sourcing rare and hard to find trees that will grow perfectly in this area and many others. We want trees adapted to the extremes of our local climate that will be productive for years to come in food forests and orchards. Who doesn't want an avocado tree on their Quinta?

The trees are self fertile so will produce a crop on their own but will produce a bigger crop with two trees present. The flowering group is A but in areas with more variation of temperature during flowering it has been proven unnecessary to have both group A and group B types. If you would like to plant a group B variety to potentially improve yields I have:

Fuerte grafted onto Mexican rootstock giving the greatest frost resistance of any rootstock.

Bacon on the same Mexican rootstock.

We also have some Hass trees on Mexican rootstock. Group A. This is the least cold resistant variety we offer but it is such a favourite! The rootstock will give you the most frost resistant Hass tree you can buy.

We are also really pleased to offer Pecan trees this April. Absolutely perfect for this area needing long hot Summers to ripen fruits and able to withstand low temperatures below -10c. These trees do well in areas that can be too wet for other trees in the Winter. During dormancy when the trees hibernate with no leaves they can stand with wet roots for days at a time. The trees can get very large but only after many years. Nut production begins year 3 or 4 after planting. You will need one of each variety as a minimum to ensure good pollination.

I don't want to encourage the cutting down of trees but 1m3 of Pecan wood is worth 6000 euros!

With the new venture starting this April we are now taking orders for these fabulous trees and others. Supplies are limited so get your orders in now to secure your trees.

Can I ask you to private message me with orders and questions rather than on this open feed.

Trees available this April are:

Mexicola avocado: 28 euros each.

Fuerte avocado: 25 euros each.

Bacon avocado: 25 euros.

Hass avocado: 25 euros.

Pecan tree variety Mahan: 40 euros.

Pecan variety Wichita: 40 euros.

Unfortunately we are unable to ship the trees this year and they are only available for collection near Alpedrinha, Fundao. If you are a distance away maybe see if a few friends are interested too and combine for collection.

I will provide all growing info required to anyone who buys trees to ensure success and buckets full of homegrown avocados and pecans!

With today's prices of avocados you don't need too many kilos before the tree has paid for your investment. When fully mature a yield of 25 kg plus is a good average! 100 euros of avocados a year for 40 yrs+!

We will have many other trees and plants available in time but if there is anything you are looking for specifically then please ask and if we can find it for you we will!

Wishing everyone a fantastic weekend.

Tristan and family.

I'm busy singing this to myself, though I don't really know why as mexicola avocados have thin, aniseed flavoured, edible skin and don't *need* to be peeled...

Also interesting to see how big the seed is :-)

David

My wife and I have been dabbling with growing avocado from seeds since we lived in Central Florida.  Her current employment is as manager of an office where the entire building front is covered with west-facing windows.  
She's been at this company for about 3 years, and we've found it to be an excellent place to grow tropic and subtropical plants IF she can manage humidity levels.  

We start seeds in standing water, changing the water out every 7-10 days.  Our germination success rate is mediocre at best.  I just tossed out a half dozen that failed to split, let alone sprout.  Once they've gotten 4-6" (10-15cm) tall off the seed, we pot them in a soil mix that contains some fine sand and a fair amount of compost.  Our eldest is currently coming up on 2 years old, and has finally bifurcated off some branches since New Years.  It stands roughly a meter tall above the soil.  I've read that depending upon conditions and variety it can take 3-7 years for them to bloom, and that presumes that we aren't dealing with a hybrid version that won't fruit.  

A couple of tips we've discovered along the way.  
1) There is a thin dark husk that serves as an outer coating.  Peel as much as possible off without damaging the underlying nut.  It will leech tannin-like compounds into the water which seem to retard growth.  

2) They prefer at least a fair amount of sand in their soil, but they also need quite a bit of organic material.  They may grow in loams or clays, but if you don't have a fairly sandy (I'd guess 25% or more) soil, augment their container.  

3) Avocados seem to be much more hardy in regards to ambient temperatures than they are to climate conditions.  To explain, they can handle heat better than they can direct sun, particularly in their first year.  When they are young, they also don't tolerate much wind.  

4) Don't be surprised if they randomly drop all of their leaves for no apparent reason.  It appears to be as much about stress as age.  We've seen them dropped because the rootball was draining the weekly water supply too ast and the soil got too dry.  They've dropped because our first fall frost in 2017 involved a low temp of about 20F/-10C, and the tree was too close to the glass window and got too cold.  Our first panic moment was when we were trying to give it proper sun, and it reacted poorly to a strong breeze (25MPH/40KPH)


I'm not sure if Europe has the traditional primary school project of sticking toothpicks in an avocado seed to suspend it in a glass of water, but that still seems to be the most effective method of starting a seed.  If you're in a low humidity area, be aware that evaporation can quickly drain the water out of the container, and if the seed dries out it likely won't ever sprout.  

Hope this helps.  

I've been looking into cold hardy Avocados lately as well. I would love to have one. Everything I have read says that the dwarf Avocado trees aren't cold hardy like some full size varieties that can take temps down to 15 degrees F. (-9.4 C). I am wondering if it would be possible to get a cold hardy full size and prune it to keep it smaller and manageable. I'm on the Swiss plateau so we have relatively mild summers and winters fluctuate. Protecting a more tropical plant would be a must. I imagine that the Italian part of Switzerland could work with some babying. So far, I haven't found anywhere to purchase a tree and starting from seed can take 15-20 years to see fruit.

Hi all,
Here is a large family nursery outside of Modena in Italy that offers Bacon, Hass, Reed and No-name avocado trees.  I haven't got any info on shipping, though.  They also sell the rootstock, called portainnesto in Italian.  http://www.maiolifruttiantichi.it/p9/risultato-della-ricerca/?nome_form=fCercaEcommerce&tipo_richiesta=ricerca-e-commerce&modalitaRicercaEcommerce=and&searchStringEcommerce=avocado&btnSearchEcommerce=Cerca

If that strange-looking link doesn't work try maiolifruttiantichi.it   then search (cerca prodotti) for avocado (same as English).

((If you are looking for organic/biodynamic heirloom fruit trees in IT there's also Omezzolli in Riva del Garda.  Don't know if they sell avocados.))

I have a bacon which survived two winters now. It is still very small, actually didn't grow much at all. It looks very healthy and I planted it in full shade protected by other trees. Did anyone try to graft avocados?

Having 3 trees, we are usually set for avocados if we ration them out throughout the winter.  But avocados do not bear evenly from year to year.  You'll get a heavy crop, followed by a light crop the following year.  Sometimes you will get 2 heavy crops in a row, but you'll most likely get none the following season.  So one tree is never enough, particularly if you want the cross-pollination of A's and B's.

On a regular basis, we are yanking baby trees out of the ground then they volunteer from the seeds.  They sprout in the compost pile all the time.  It seems like they grow much more aggressively from seed than they do from grafted trees from the nursery.  For those of you wanting Haas or Fuerte, I wish I could send you some seedlings.  We've got a million of them.

While we don't have to contend with frost here, it's still best to plant them on hillsides where the air is moving when it gets cold.  A south-facing hillside (for those of us in the northern hemisphere) with some sort of block wall or other heat sink would seem best.  But that same south facing hillside will need to be aggressively mulched and regularly watered in the hot months.  Avocados have shallow roots.  Without a heavy mulch layer, the hot sun will cook the roots on a south facing hillside.  I plant peanuts all around my avocados as a ground cover, and the two plants seem to do well together.  

Hello,
it got quite cold a few weeks ago and all my avocadoes died! I didn't protect them well enough. Some might sprout back from the roots.
Anyone who wants to try this please remember :Young avocado plants, grafted or not, can handle NO FROST whatsoever.
Those so-called cold-hardy varieties down to - 10 Celsius only have that resistance when they have bark and are big, in my opinion.
I won't give up just yet though....

Philip Heinemeyer wrote:it got quite cold a few weeks ago and all my avocadoes died! I didn't protect them well enough. Some might sprout back from the roots.
Anyone who wants to try this please remember :Young avocado plants, grafted or not, can handle NO FROST whatsoever.
Those so-called cold-hardy varieties down to - 10 Celsius only have that resistance when they have bark and are big, in my opinion.
I won't give up just yet though....

Hello Phillip,
I am sorry for your avocado. I live in south of France (Nîmes) and all my avocados has been defoliate this year. Hopefully, they will comeback... I not 100% agree with what you say. In my garden small avocado plants can handle frost (-5°C) without damage. But this year the weather was very cold (-9°C), and last a long time with snow (15 cm). On my blog, I post few pictures ( http://www.acclimatons.com ). Temperature is a main factor for avocados. The age of the plant play a role, but maybe not has important has you mention ? In Nîmes even aged avocado trees has sufferer this year (5 meters high, no leafs, brown branches). I have not noticed any difference between mexicola, bacon or fuerte seedings concerning cold hardiness.
Good chance for acclimating avocados in center Bretagne.
Benoit

You don't have to have two varieties of avocado. A single tree self pollinates with the help of bees that return in the afternoon. Research does show that cross fertilization seems to reduce fruit drop (avocados form hundreds of small fruits but most drop when they are the size of a pea).
The Fuerte, which means "strong," is the most cold tolerant (not really tolerant but can survive brief periods - it's not going to grow in northern France). Fuerte became became THE California avocado after a cold snap killed other varieties. The Hass later replaced Fuerte as the market leader. I grow both, along with Pinkerton and GEM. Trees can be tricky to get started - the young trees seem to want to die - but when one gets big you can hit it with a truck and the truck will lose.

We germinate the pits in our worm bed, dig out the little trees, then place in pots. So far so good. When the weather cools, we bring them indoors. They've lived a few years like this. Perhaps one day it will forget it's in the mountains and produce fruit. haha we are hopeful.

This website is a good read, lots of info on avocado varieties. https://toptropicals.com/html/toptropicals/articles/fruit/varieties_avocado.htm

In this guy's video he says his Bacon avocado survived our cold winter in England a few years but it died in the summer drought we had after! He is in Kent so it is generally a little warmer and sunnier than here but it reached -8C here that winter and probably was a similar overall temperature there too. So making use of microclimates is key!

I live in zone 9a and have successfully grown lots of baby avocado trees from pits as well as scoring 2 mexicola grande saplings on clearance at the local co-op. (But even here we have to protect the babies from frost for several years!) Several of my trees flowered for the 1st time and then succumbed to the dreaded laurel wilt! If you have this fungus in your area your avocado trees will die sooner or later. But hopefully you will get some fruit 1st!!! I haven't given up...I keep hoping one of my seed grown babies will show resistance. Anybody have any info on a variety that is both cold hardy and wilt resistant?  Anybody in the north Florida /coastal Alabama area interested in a cooperative effort to breed laurel wilt resistant trees?

The most cold hardy avocado variety sold in Australia is Bacon Avocado, which manages to grow in Melbourne (frosty but not snowy).

Avocados also die from strong sunlight because their leaves burn easily, so Mediterranean climates like mine (South Australia) are really difficult for avocados. They also need very free-draining soil. Mine died pretty easily, but the plum trees next them thrived. I’ve given up on them and am focusing on what actually grows easily in my climate.

Mexicola update!
This is how my mexicola avocado looks like right now. It seems to be doing slightly better than last winter, but we only had two mild frosts.
Its frost resistance for now is nowhere near -7 Celsius (19.4 Fahrenheit) but if it keeps surviving the winters and growing a bit each year who knows....
I remain convinced that young trees have very little frost tolerance. It should increase when they get older.
So protect them while they are young.
The tree is four foot tall and it was already getting dark when i thought of taking pictures.

I've been thinking about planting a Mexicola Avocado, and will probably pick up a 2 foot tall one from a local nursery sometime this year.  I was curious if anyone had any pointers on the best time of year to plant them, or if there's an ideal soil temp to plant them at?  I've mostly planted temperate trees in the past, and often plant those in the fall, but I'm guessing an avocado would do better planted sometime in the spring?

If i was you i would plant it after the last frosts, probably end of may in oregon.
And for its first winter i would build an igloo type structure out of hazel rods held together with wire
to be able to easily put a frost cover over it.
You can also place plastic gallons of water around it in a circle, around the trunk under the frost cover or bubble wrap.

Thanks for the advise! I'll aim for May then.  I live in a weird part of Oregon where we almost never get frost (and the ground has never frozen in the 10 years I've been here), but while other parts of Oregon are freezing we have regular 33 degree nights, which I'm guessing still would be detrimental to a young avocado tree.  May's definitely when soils finally start warming up.

I'll plan on setting up the cold frame next year as well, as every couple years we get a few nights in the upper 20s.

I'm trying to source grafted Mexicola saplings in the UK but I'm having difficulty finding anyone in the US who will ship them to me, does anyone know of a nursery that will or anyway I can get around this?

Try Tristan Coverdale, he might be able to help you.

As I understand it though Mexicolas aren't grafted.  They're more of a landrace and grown from seed.

I have sent him a message but no reply as yet.
I've looked for actual Mexicola avocado suppliers and can't find any that ship to the UK, seems to be very difficult to get hold of and I'll be needing a fair quantity as well.