Air layer—how small is too small?

[WNC Bonsai]

I have several J. maple saplings that have shot up tall and thin over the last couple of years. They are now in the ground to thicken up but I am thinking that instead of just cutting them back I might air layer a couple. They are about 1/4” thick at the possible air layer point so I am wondering whether that is too thin and they might snap in a stiff breeze. They’re going to need to be pruned back anyway so probably nothing lost if they do snap but if they can be stabilized I can double my stock for a forest planting. Any thoughts?

 

[penumbra]

They should work fine and root faster than larger layers. It is easy enugh to stabalize the air layer by using a stake.

 

[HorseloverFat]

I agree, just consider it a slow cutting.. or a fast layer... the size of the specimen SHOULDN’T effect the effectiveness.

I am doing a layer on a grafted (actually a VERY good graft, but MOST Oregon trees, packed in straw, are well tended) Tancho Trident, a little over a month ago.it is roughly 2/3 of an inch. The top is still just... being a springtime tree.

 

[WNC Bonsai]

Interestingly the green one has put out roots and I may separate it soon. However the red one is a total failure. When I checked them yesterday all the leaves on the layered section were total crispy critters. The lower section is still healthy so I guess I managed to cut off water flow up the xylem. These little stems apparently don’t leave a lot of margin for error.

 

[andrewiles]

I think I've had that problem too. My experience is limited, but I've seen more dieback on the top for very thin layers. I think it's easy to cut too much of the sapwood when slicing through the cambium.

 

[hinmo24t]

I have several J. maple saplings that have shot up tall and thin over the last couple of years. They are now in the ground to thicken up but I am thinking that instead of just cutting them back I might air layer a couple. They are about 1/4” thick at the possible air layer point so I am wondering whether that is too thin and they might snap in a stiff breeze. They’re going to need to be pruned back anyway so probably nothing lost if they do snap but if they can be stabilized I can double my stock for a forest planting. Any thoughts?

View attachment 378159

nice beech, bottom right?

 

[0soyoung]

A new internode doesn't have distinct rings of xylem and phloem separated by cambium cells. Instead there are xylem/phloem bundles positioned around a pith core. So, one cannot layer new growth.

Over time, the bundles merge to form the so-called secondary structure that we know for trees. I think this can happen to the initial internodes of the year, before their first growing season is over. Certainly it exists by the second year. So we could attempt to cut a girdle on last year's growth, maybe even on a hardened internode of this year's growth.

But, trees compartmentalize damage. There is certainly a layer of living cells between the pith and the first ring. We are inherently going to damage the wood of this first ring in making a girdle. In response, living cells in the wood will clog the xylem lumens - we've just made a cutting, in effect.

Clearly, we need at least one more season of growth = another growth ring of wood --> the stem needs to be at least 2 years old.

 

[sorce]

Far as working to reproduce material, I don't think there is a too small.

For me, one of the largest benefits of layers is the ability to regrow roots in proportion to the trunk, which taking thin layers kind of negates, has you starting at "seedling" again.

Sorce

 

[Pitoon]

Air layering stock that is to thin can result in it snapping at the girdle........extra care is needed.

 

[WNC Bonsai]

A new internode doesn't have distinct rings of xylem and phloem separated by cambium cells. Instead there are xylem/phloem bundles positioned around a pith core. So, one cannot layer new growth.

Over time, the bundles merge to form the so-called secondary structure that we know for trees. I think this can happen to the initial internodes of the year, before their first growing season is over. Certainly it exists by the second year. So we could attempt to cut a girdle on last year's growth, maybe even on a hardened internode of this year's growth.

But, trees compartmentalize damage. There is certainly a layer of living cells between the pith and the first ring. We are inherently going to damage the wood of this first ring in making a girdle. In response, living cells in the wood will clog the xylem lumens - we've just made a cutting, in effect.

Clearly, we need at least one more season of growth = another growth ring of wood --> the stem needs to be at least 2 years old.

I think this was their third year and both were the same age and diameter. There was a distinct bark layer that I peeled off then scraped the wood to remove the cambium and prevent bridging. The green one rooted the red one died.

 

[WNC Bonsai]

Air layering stock that is to thin can result in it snapping at the girdle........extra care is needed.

Yes, to be safe I ran the wire around a stake both at the top of the plastic and the bottom to provide support since these were kind of thin.

 

[Pitoon]

Yes, to be safe I ran the wire around a stake both at the top of the plastic and the bottom to provide support since these were kind of thin.

I've snapped many in my air layer attempts.

 

[0soyoung]

I think this was their third year and both were the same age and diameter. There was a distinct bark layer that I peeled off then scraped the wood to remove the cambium and prevent bridging. The green one rooted the red one died.

So a two-year old stem can be layered.

 

[WNC Bonsai]

So a two-year old stem can be layered.

I think it will depend on the variety. I was watching a Peter Chan video yesterday where he looked at his successes and failures and he pointed oit some varieties that are easy to root and others that are not. Mine were grown from seeds collected in the neighborhood so are probably just common ones like the generic green and purpureum. Given the large number of varieties it will likely be a hit and miss kind of thing.

 

[0soyoung]

I think it will depend on the variety.

Yes, of course it does. But the thread title is 'how small is too small'.

Peter Chan video yesterday where he looked at his successes and failures and he pointed oit some varieties that are easy to root and others that are not.

And, as I've documented here, there are additional causes of layering failures. Auxin in the polar auxin transport stream (auxin handed off from one cambium cell to those below) controls the life of cambium cells - too little auxin is the message that there is no life above, so they produce an ethylene+jasmonate message to seal off the xylem and commit suicide. Leaves above the girdle desiccate in a matter of days, just like would do if it was cut off the tree. One likely finds blackish punky bark immediately below the girdle when this happens. If this sort of thing did not happen, one could indeed wait 'forever' (the life of the tree) for a layer to root.

yada, yada, yada. But this detail has no size relationship = off topic

 

[WNC Bonsai]

Yes, of course it does. But the thread title is 'how small is too small'.

And, as I've documented here, there are additional causes of layering failures. Auxin in the polar auxin transport stream (auxin handed off from one cambium cell to those below) controls the life of cambium cells - too little auxin is the message that there is no life above, so they produce an ethylene+jasmonate message to seal off the xylem and commit suicide. Leaves above the girdle desiccate in a matter of days, just like would do if it was cut off the tree. One likely finds blackish punky bark immediately below the girdle when this happens. If this sort of thing did not happen, one could indeed wait 'forever' (the life of the tree) for a layer to root.

yada, yada, yada. But this detail has no size relationship = off topic

Personally I think there was just insufficient xylem to transport enough water so it just dried up and died. At any rate I removed the remaining one today and itis doing fine in a new pot alongside the two zelkovas I air layered at the same time.

 

[0soyoung]

Personally I think there was just insufficient xylem to transport enough water so it just dried up and died.

Yes. But before you cut a girdle, there was sufficient xylem to transport enough water. That is, it grew to be what it was before you touched it. So there was enough xylem originally. The question is where did all the water carrying capacity go?

 

[RJG2]

If this sort of thing did not happen, one could indeed wait 'forever' (the life of the tree) for a layer to root.

Tried to air layer a dissectum type Japanese maple a couple years ago (before I knew any better). No cambium connection and the branch is still alive and well.

Might score it and try again just for fun, even if it doesn't make a great bonsai.

 

[cmeg1]

Younger ones air layer quicker in my experiance…especially first or second grow season whips.like in one to two weeks…..sometimes like 4 days!!!!!

 

[RJG2]

Younger ones air layer quicker in my experiance…especially first or second grow season whips.like in one to two weeks…..sometimes like 4 days!!!!!
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Are you scraping away the cambium here, or just putting on some hormone and wrapping with rock wool?