Burying Avocado beneath the graft

[Va Beach Grower]

Hi All,
I have a question, I'm in zone 8A, and for fun I grew Haas from seed, and right when it sprouted, I grafted a Wilma (that I got from a member of this forum onto it (just a very small branch).  Just experimenting a bunch w/different methods of grafting and trying to grow from cuttings.  Anyways, this graft took off and it's grown very fast in a short amount of time.  So now I have a Haas root w/Wilma, and the Haas will probably not survive the winters outdoor here.  But I read something that if you bury below the graft that new roots will probably form from the Wilma.  I realize for a dwarf that would be a problem, but I actually want a full tree and the goal is to grow Wilma, so if I bury well below the graft line, I figure that this will actually help grow a full Wilma rather than a grafted Wilma.  Maybe that's a mistake, but I'm hoping a Wilma can actually handle the outdoor winters in virginia beach (but Haas will not).  Please let me know if that logic is sound?

[Galatians522]

Your idea sounds plausible. I read a description once explaining a method of propagating dwarf avocado rootstock. The desired rootstock variety was grafted onto a seedling and a metal ring was slipped over the graft at the time of grafting so that it would girdle the seedling rootstock and force the scion to root. The process obviously required that the graft be burried below the soil line.

[Va Beach Grower]

Your idea sounds plausible. I read a description once explaining a method of propagating dwarf avocado rootstock. The desired rootstock variety was grafted onto a seedling and a metal ring was slipped over the graft at the time of grafting so that it would girdle the seedling rootstock and force the scion to root. The process obviously required that the graft be burried below the soil line.

On that note of girdling, do you think it would be best to "scar" above the graft union where the new scion has grown, so when that scar is planted underground, that new roots form from there?  So sort of like air layering, except instead of doing it the normal air layer way, I just bury the scar underground so that's where new roots begin?

[drymifolia]

I've tried this a few times and never had luck getting roots to form above the graft, but I wouldn't be surprised if it's something where some cultivars do so more readily than others. I've dug around the trunk of buried grafts up to 2 years later and found zero sign of above-graft roots.

The method used to create clonal rootstocks by Brokaw is similar, though, using a nurse root and etiolation, I don't know their exact process but they've said it's based on the method proposed in the 1971-1972 CAS Yearbook by Frolich & Pratt, so I'd recommend reading that if you want to replicate their success:

https://www.avocadosource.com/CAS_Yearbooks/CAS_55_1971/CAS_1971-72_PG_097-109.pdf

I've personally had better luck rooting nearly mature growth cuttings as I've discussed in a thread on another forum.

[Va Beach Grower]

I've tried this a few times and never had luck getting roots to form above the graft, but I wouldn't be surprised if it's something where some cultivars do so more readily than others. I've dug around the trunk of buried grafts up to 2 years later and found zero sign of above-graft roots.

The method used to create clonal rootstocks by Brokaw is similar, though, using a nurse root and etiolation, I don't know their exact process but they've said it's based on the method proposed in the 1971-1972 CAS Yearbook by Frolich & Pratt, so I'd recommend reading that if you want to replicate their success:

https://www.avocadosource.com/CAS_Yearbooks/CAS_55_1971/CAS_1971-72_PG_097-109.pdf

I've personally had better luck rooting nearly mature growth cuttings as I've discussed in a thread on another forum.

Thanks, I've tried a few different ways of air layering (on other trees) without success so far, as well as trying to root from cuttings, but again I'm new and didn't have any success, except w/rooting 2 from cuttings from a Bacon Rootstock.  So, even if the rooting above the graft doesn't work, since I grafted onto a haas seedling (very low down - soon after it came up), if I just bury it a few inches below the graft, I figure that the added warmth of the soil will be better than the haas being above ground, so maybe even if it doesn't root on the Wilma, if the haas is a few inches underground, then it may survive the winter?  Typically we don't get below freezing in Va Beach, but last year we had a 20 degree week (which is not normal here) and I'm hoping to get this in the ground.  It's only about a foot tall, so maybe best to bring inside for winter, but I'm willing to give outside a shot if burying below the graft does seem like a reasonable thing to do to keep it warm.

[ScottR]

I've tried that before with a Duke 6 scion on mexican rootstock and i buried below graft to see if Duke would grow own roots but no luck. Still have tree with Koala grafted on one trunk and Duke on other trunk. If I remember right I believe I sliced into scion and put rooting hormone on before burying.

[drymifolia]

So, even if the rooting above the graft doesn't work, since I grafted onto a haas seedling (very low down - soon after it came up), if I just bury it a few inches below the graft, I figure that the added warmth of the soil will be better than the haas being above ground, so maybe even if it doesn't root on the Wilma, if the haas is a few inches underground, then it may survive the winter?  Typically we don't get below freezing in Va Beach, but last year we had a 20 degree week (which is not normal here) and I'm hoping to get this in the ground.  It's only about a foot tall, so maybe best to bring inside for winter, but I'm willing to give outside a shot if burying below the graft does seem like a reasonable thing to do to keep it warm.

My vote is bring it in this winter and then plant it out early in spring, after you suspect your last hard freeze has passed but ok if mild frosts come after. That's been my best time to plant. Then you get a full growing season in the ground before the first winter test.

I've had Hass seedlings die even when the graft is planted 4" below ground. Zero Hass seedling survival rate in two winters. But our subsoil gets down around 40°F in winter for months on end without sunny days to warm it, so I think Hass seedlings struggle with long-duration cool roots. Lowest temperatures those two winters were 16°F and 17°F, which is unusually cold for here, but many Mexican roots made it through fine. Our average winter minimum over the last 30 years is more like 22°, and in recent years more like 25°F, but we were still zone 8b when USDA last updated their map in 2012, so I still say 8b even though we are more like 9a now.

[Galatians522]

Your idea sounds plausible. I read a description once explaining a method of propagating dwarf avocado rootstock. The desired rootstock variety was grafted onto a seedling and a metal ring was slipped over the graft at the time of grafting so that it would girdle the seedling rootstock and force the scion to root. The process obviously required that the graft be burried below the soil line.

On that note of girdling, do you think it would be best to "scar" above the graft union where the new scion has grown, so when that scar is planted underground, that new roots form from there?  So sort of like air layering, except instead of doing it the normal air layer way, I just bury the scar underground so that's where new roots begin?

For a girdle to really force rooting, you have to girdle all the way around. Simply wounding does not work in most species unless they also ground layer (like mudcadine grapes). The etoliation article Drymifolia posted looks more reliable. One of the keys that I noted in the article was that the shoots must be in the new growth stage when they are buried to etoliate. Otherwise, the cells won't be able to "switch gears" and start forming roots. Looks like your best option would be to cut it back and bury in perlite as soon as new shoots start forming. Then girdle and allow to root.

[fishie]

I actually saw a video on how they make the clonal rootstock on avocados recently on YouTube. Growing in darkness was important.

https://youtu.be/FVEP11S1Nuc?si=gFDdjAnXhIim2KBO

[Va Beach Grower]

I actually saw a video on how they make the clonal rootstock on avocados recently on YouTube. Growing in darkness was important.

https://youtu.be/FVEP11S1Nuc?si=gFDdjAnXhIim2KBO

Ha, I actually added this to my playlist yesterday   I self-admittedly am not good at grafting, but I have gotten a bit better lately.  What I might do since we're coming closer to winter, is start some haas nuts in water method, grow those out a bit and try to graft some scion onto it early, and then try a young air layer maybe?  I don't have preferred root stock, so I imagine I don't need the double graft and can just try to root from the initial graft, cut off and then plant.  My Mexicola is doing decent (only a few feet though), but I may try to cut some scion so I can mess w/it over wintertime and do some low grafting.

I'm wondering if anyone has tried grafting early and if the seed is still in water and in early development?  I grafted early on Haas and it worked out well for a few of them, but I haven't air layered off yet to try and grow new roots, but maybe that can be my wintertime project.  I'm hoping to avoid taking too much soil inside during winter, so wonder if you can graft to a seedling while it's growing in water, or if it just doesn't get enough nutrients?

[drymifolia]

I'm wondering if anyone has tried grafting early and if the seed is still in water and in early development?  I grafted early on Haas and it worked out well for a few of them, but I haven't air layered off yet to try and grow new roots, but maybe that can be my wintertime project.  I'm hoping to avoid taking too much soil inside during winter, so wonder if you can graft to a seedling while it's growing in water, or if it just doesn't get enough nutrients?

I do NOT recommend using the "water method" to start avocados. I have much better, healthier plants that grow more strongly in later months when they are started in soil. I use these:
https://stuewe.com/product/deepot-lightweight-cell-2-7-x14/

And they look like this just a few months after sprouting:


I saw that Craig Hepworth is selling Del Rio seeds via his Instagram account (@floridafruitgeek) for $10 apiece. I'd recommend those before he sells out! But start them in soil, not water. Then you won't need to worry about hardiness of the roots as much.

But as for your actual question, I've had some success grafting very young seedlings, but mostly I wait until later, both because it is hard to not damage the soft stems and also because I'm growing potentially cold hardy seedlings and mostly I want to graft them high enough to encourage a rootstock branch to grow later, to evaluate it for hardiness.

[fishie]

I'm wondering if anyone has tried grafting early and if the seed is still in water and in early development?  I grafted early on Haas and it worked out well for a few of them, but I haven't air layered off yet to try and grow new roots, but maybe that can be my wintertime project.  I'm hoping to avoid taking too much soil inside during winter, so wonder if you can graft to a seedling while it's growing in water, or if it just doesn't get enough nutrients?

I do NOT recommend using the "water method" to start avocados. I have much better, healthier plants that grow more strongly in later months when they are started in soil. I use these:
https://stuewe.com/product/deepot-lightweight-cell-2-7-x14/

And they look like this just a few months after sprouting:


I saw that Craig Hepworth is selling Del Rio seeds via his Instagram account (@floridafruitgeek) for $10 apiece. I'd recommend those before he sells out! But start them in soil, not water. Then you won't need to worry about hardiness of the roots as much.

But as for your actual question, I've had some success grafting very young seedlings, but mostly I wait until later, both because it is hard to not damage the soft stems and also because I'm growing potentially cold hardy seedlings and mostly I want to graft them high enough to encourage a rootstock branch to grow later, to evaluate it for hardiness.

I have had bad results with water long term as well. Those roots look great with the deepot. Reminds me of the sleeve that Brokaw uses. Have you found the best place to buy is direct from Stuewe? Their shipping is pretty high.

[Va Beach Grower]

So after looking at frolich method, I realize they want certain rootstock,  but is there a reason why you couldn't just do a single graft? So start from Haas seed, graft with desired variety, put in the dark after initial growth, then scar and try to get to root, then just cut off and you've got a single variety that you want.  I don't need dwarf or anything,  just cold hardy variety. This method seems basically the same as air layeringbut with the dark part.

[drymifolia]

Yeah it was developed as a way to clone rootstocks, but there's no reason it can't instead be used to make own-root clones. And yes, using a "nurse root" is similar to an air layer in many ways. And air layers are actually in darkness too, at least the part you put under the soil or rooting medium!

I will say again though that I've had better luck simply taking cuttings and following basically this method of rooting without any nurse root needed:

• Take "almost fully expanded" softwood cuttings from last flush in fall, keeping only the 2 to 5 newest leaves
• Place those in regularly changed water in a warm place until callus forms, usually a few weeks (discard any that wilt in this stage)
• Place the callused cuttings in potting soil under a humidity dome (clear takeout containers or jelly jars work well). A heating pad may be helpful in this stage, I use one in my greenhouse because it's cold in there.
• Remove the dome every few days and mist them. Discard any that wilt.
• Any that haven't wilted by spring (4ish months later) get their humidity domes removed. Discard any that wilt at this stage, water the rest on the same schedule as avocado seedlings (frequent when hot/dry, infrequently when damp/cool).
• By mid-summer you should see feeble new growth (usually very small leaves that barely expand), and that may be the only growth that year. Some clones put on a second flush late summer, some don't.
• I keep the successful clones in the greenhouse for a second winter, and the next spring they usually start to grow very vigorously, and get potted up or planted out in early summer.

The initial growth rate is slow (more than a year until vigorous growth starts), and success rates vary widely, though so far my sample sizes are very low. I had nearly 100% when cuttings are taken from young seedlings (I've done dozens of these), for Opal it was 100% with sample size of 1, Aravaipa was 66% (2 of 3 attempts) , 25% for Jade (1 of 4), and so far Duke is proving to be virtually impossible (0 of 12 attempted, though a few made it to humidity dome removal before giving up, so they may just need the dome longer). Some of the lesser known cultivars have done very well, 100% for Linh (2 of 2), 50% for Long South Gate (1 of 2), for example.

[Va Beach Grower]

Yeah it was developed as a way to clone rootstocks, but there's no reason it can't instead be used to make own-root clones. And yes, using a "nurse root" is similar to an air layer in many ways. And air layers are actually in darkness too, at least the part you put under the soil or rooting medium!

Thanks for this.  A member of this site had a side-bar conversation w/me and sent me a bunch of Wilma cuttings last year to help in my attempt to graft as well as root cuttings.  I followed (or thought I did anyways) most of the steps you've outlined but I don't know if I got any of the cuttings to root.  A few scion's worked on grafting but many died (b/c I'm a newbie at grafting, but getting better at it).  I did some air layers on my apple tree and they did grow roots, and I like the minimal care needed for that, however I should have let them stay on longer as the roots were not vigorous.  1 died and 1 may make it, we'll see.  The Wilma that I grafted onto the haas seedling is doing really well, but if you think it won't survive outdoor winter, then I probably need to do something else.  I can bring it inside for winter but space is tight, and I realize an air layer takes time, but maybe it's worth doing it for that one where the graft did take.  I have tried a lot (and failed a lot, but learned a lot) so far.  Ideally I'm just hoping to be able to get a tree or two to get to the stage of fruiting after some years.  The VA Beach climate is relatively mild so I think other than a week or two spell in winter, it may be a place where an Avocado tree can survive outdoors.  I did try the  humidity done on blueberry cuttings, but softwood cuttings, and all failed (but I may have been spritzing it too often and drowning the cuttings.  My Mexicola is small, but maybe large enough where I can take a few cuttings from it and give it a shot this winter for the cuttings.  Thanks for the tips!

[drymifolia]

Have you found the best place to buy is direct from Stuewe? Their shipping is pretty high.

I have bought them from the Greenhouse Megastore as well, which is free shipping on orders of $100+, but the price is almost twice as much per pot so I don't really know which one ends up being better. I only ordered them from GHMS because I was ordering other things and it came to only $80 so I added 25 deepots to get the free shipping. I haven't really shopped around beyond that.

[fishie]

Have you found the best place to buy is direct from Stuewe? Their shipping is pretty high.

I have bought them from the Greenhouse Megastore as well, which is free shipping on orders of $100+, but the price is almost twice as much per pot so I don't really know which one ends up being better. I only ordered them from GHMS because I was ordering other things and it came to only $80 so I added 25 deepots to get the free shipping. I haven't really shopped around beyond that.

Thanks for the info. Trying to decide if I need 270 of them lol. Very interesting information on rooting the cuttings as well.

[Galatians522]

You could always sprout a cold hardy seed and then approach graft to your existing tree. Tha5 has a high success rate.