Cold hardy avocado - from seed

[Solko]

Here is post to share my limited experience growing cold hardy and drought tolerant avocado trees from seeds.

I started doing this in 2010 and have tried a lot of different seeds and methods and I am myself quite surprised at what seems to work best, so I thought I would share.

Background: I live in the Netherlands, in Northern Europe, climate zone 8b. I have a small garden in Portugal, climate zone 9a, with a very dry summer and I want to get some avocado trees going there. I have no irrigation or winter protection.

Over the years I have read so much in the web and I have tried most methods that one can find, so here is what worked best for me in the end: sowing massive amounts of seeds of a diversity of avocado's in small 'nursery patches' and then let Darwinism do the rest of the job.

The first two years I started doing the traditional way: germinating seeds of store-bought avocado's in pots at home and planting them out when one or two years old. I transported around a hundred seedlings like this from the Netherlands to Portugal, planted them one by one carefully and NONE of these survived. This seems to be the preferred method for professional growers, but when you don't have irrigation or the time to give the seedlings aftercare when you plant them it is very easy to lose them.

These first two years I also just planted loose seeds all around the terrain. All of them came up, some took more then a year, but all of them came up, but they had a lot of trouble competing with the weeds and ferns, and they somehow stayed very weak and small in the dry ground.

The third year I really took the time to dig a small garden bed and amend the soil with two large bags of good potting soil and planted around one hundred seeds of Hass, Reed, Pinkerton, Zutano and Bacon avocados, that I found at the local market in the Netherlands and I kept eating the rest of the year. It basically took me seven years of eating three avocados a week to get my trees going - but I am not complaining 

This worked very well the next year the bed was full of seedlings - they were doing fine for two years, but I lost them all in a very dry year - one hundred seedlings competing with each other on one square meter in a dry summer is too much!
But I already started to notice that there was really no pattern in which seeds survived either the summer or winter well - of all the cultivars it was equal amounts.

I started making small amended nursery beds all over the terrain in which I showed only eight to ten seeds and let them germinate by themselves. From all these beds at least one grew into a healthy tree.
Now they are starting to become as tall as myself and next year I will be ready to do some grafting.

[Solko]

So far so good, but now for the more surprising results.

In the last years I have been saving all those avocado seeds I ate to bring them to Portugal in the fall or spring. I always had avocado seeds lying around somewhere in the kitchen and a big plastic bag with them in the bottom of the fridge. That works fine to keep the seeds alive for over a year.

But all the semi rotten or dry seeds, or those I couldn't take with me because my luggage got too heavy, all those I just planted in my garden in the Netherlands in some 8b. And they grew there...
And by coincidence we didn't get a severe winter for two years in a row, until this last winter gave us some real freezes and a month or two of real winter weather. Frost at night, dark and wet weather and at least one whole week of frost day and night. So all the young trees in my backyard here died. All but two of them...
And those were NOT from the very sought after Mexicola seeds (that are almost impossible to come by in Europe)

My philosophy is now that the best way to find a good rootstock avocado for a marginal climate, or a cold hardy variety is to just plain and simply plant a lot of seeds of different cultivars directly in the spot where you want the tree. I am sure that in general certain varieties give a better percentage of success, but on the other hand it seems that even in the Guatemalan and Carribean strains of all commercial cultivars the genetic variety is so great and offspring so unpredictable, that you can probably find a survivor for your specific climate conditions within one hundred seeds. That is eating one hundred avocados and being reasonably sure you will have the perfect rootstock for your own soil and climate.

Here are the trees coming out of winter. About ten of them seems to be alive, all defoliated, but they looked green.


But upon closer examination I found black spots of frostbite on most of the surviving stems.


Here a close up of frostbite. The trees start oozing salts and quickly die back completely to the root.


Here you see the other trees dying, the green stem in the foreground also lost all it's leaves, but didn't have a single black spot in it and is now leaving out again vigorously. After a cold winter and a week of real frost. In the background you can see a new batch of avocado seeds 


While some of the other trees also came back, but from their roots and my guess is that they will freeze back again next winter.

[Solko]

I know it is a long process to start trees from seeds, but I must say that it is a very satisfying, albeit a somewhat slow way to start a garden. And I think the advantages are not just theoretical. I really think you end up with better rootstock for most of your trees and you might discover some new or strange cultivars along the way. I enjoy the journey and the learning process just as much as having to eat three avocados a week 

Anyone else care to share their experiences with planting from seed?

[simon_grow]

Thanks for sharing your story. I did something similar with Avocado but I don't think we get as cold over here compared to where you are at. Avocados typically grow wonderful here except some locations have ultra high clay, rocks, salt or very poor drainage and anecdotal evidence suggests that in situ planted seeds for some reason seem to adapt better and grow with more vigor in these marginal soils.
http://tropicalfruitforum.com/index.php?topic=12844.0

I'm also planting lots of random mango seeds directly into the ground for the same reason. I hope you get a few trees to survive the summer and winter. The trees should get a bit more cold hardy and be able to withstand drought better as they increase in size.

Simon

[TucsonKen]

Good idea--if you have the space, planting seeds might yield some nice surprises. And, if you don't want to wait as long, you could always graft named varieties onto the healthiest seedlings.

[Solko]

Yes, that is what I thought as well. I am going to start grafting the trees with named varieties next year, and keeping one branch per tree of itself so that i can sample the fruit. I've read that that will be very difficult with avocados, because they can have very different levels of vigor and growth, so one variety has the tendency to outgrow any other on the same tree. I'll just give it a try and if it doesn't work, no big deal.

We cannot find scions of that many different varieties here in Europe. The only ones available to my knowledge are Hass, Reed, Bacon and Zutano. If anyone knows a good nursery or place to get avocado scions, please let me know.

[Solko]

Simon, that is a great thread, thanks for reminding me of it. I guess the only thing I do different is that i plant twenty times more seeds than the number of trees i eventually want. And that I wait for a couple of years and let drought and cold already do some severe natural selection on these seedlings before i consider them for grafting. So i graft on older, established young trees.
The only serious drawback, besides the extra time it takes to get a tree, is that you don't really control where the trees end up on your terrain. Even though I think I choose good spots for them, some seedlings survive in other spots and make me constantly redesign my planting plans for other trees. But fortunately constantly redesigning what I am doing is something I like to do 

[gnappi]

It looks like you did not get the memos regarding amending the soil before planting, neither did I :-)

I remember folks in California, or was it Arizona who found that planting avo or mango seeds in native soil and eventually top working them was be far better than buying nursery grown trees.  Keep the forum posted on your results.

Here's a good read on seedling avos.

http://tropicalfruitforum.com/index.php?topic=2097.0

[lajos93]

Hi

Do you have any updates?