Mid-summer air layer separation

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Omono
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This year I decided to air layer my slippery elm to get rid of a large surface root so I made the cut about June 1st. I really had not anticipated that it would take root so fast and am now faced with a sphagnum rootball about the size of a softball. Ideally I would like to spread the roots out radially and pot it up in bonsai soil, however given the timing I am not sure how to proceed. I could just add more sphagnum, rewrap it, and let the roots grow for another month. Or I could pop it into a pot full of moist sphagnum moss like Peter Chan does and let the roots fill the pot, then repot later in September or next spring. Also how much of the canopy should be removed? Below are photos.

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BobbyLane

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Wow what a result. those would be still too delicate to tease out but yeh you could slip it into a flowerpot temporarily i reckon. ive often heard Will baddley say his elm layers root in 6 weeks, i have some beech layers going with no signs of roots yet!
 

Ohmy222

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I wouldn't mess with the roots very much.. They will be very brittle. I would cut off and put in a pot of bonsai soil. I would even leave the moss. The roots will venture out into the more porous bonsai soil and you can clean it up in 2023. If you are aggressive you could tease out a very small section and slowly work your way around but I have messed that up before. Normally if I am doing a layer low like yours, I will wrap with moss and wire the moss to the tree. Then I will cut a pot and place around the root base and fill in with bonsai soil. That way it doesn't wrap around the ball of cellophane like you have. You did nothing wrong though. I only use the pot when the layer is low to the ground.
 

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Wow what a result. those would be still too delicate to tease out but yeh you could slip it into a flowerpot temporarily i reckon. ive often heard Will baddley say his elm layers root in 6 weeks, i have some beech layers going with no signs of roots yet!
Yes, this one was a real surprise. I did 2 J. maples, 2 zelkova, 1 chinese elm, and this one all at the same time. This one and 1 of the maples are the only ones to root so far.
 

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I wouldn't mess with the roots very much.. They will be very brittle. I would cut off and put in a pot of bonsai soil. I would even leave the moss. The roots will venture out into the more porous bonsai soil and you can clean it up in 2023. If you are aggressive you could tease out a very small section and slowly work your way around but I have messed that up before. Normally if I am doing a layer low like yours, I will wrap with moss and wire the moss to the tree. Then I will cut a pot and place around the root base and fill in with bonsai soil. That way it doesn't wrap around the ball of cellophane like you have. You did nothing wrong though. I only use the pot when the layer is low to the ground.
I had thought of using a pot but the low side branch prevented it and I wanted to keep it so I went the traditional route.
 

Rodrigo

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I recently watched a Mirai video on air layers and he said that for deciduous, he recommends separating the following spring before bud break. Reason being that there needs to be enough roots in the layer to support the tree (you shouldn't need to cut foliage for the roots to have less to support. You have enough roots to support the foliage you have) , and yours looks like a rather large tree so you need enough roots.
That's what I'm doing with mine, just wanted to pass on my two cents. Great tree!
 

penumbra

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This is my all time favorite among elms. Leaves are of a manageable size and have a nice red flush to new growth. Too late this year but I will air layer mine next year.
 

Shibui

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I had thought of using a pot but the low side branch prevented it and I wanted to keep it so I went the traditional route.
A low branch does not exclude the pot option. Plastic nursery pots can be cut to any height to fit anywhere. I would still see that as an option now - remove the bottom and enough height from a suitable sized (diameter) pot and split one side so it can be fitted round the trunk and new root ball. Then you can remove the plastic (leave the current moss and new roots as they are) put the pot in place and fill with soil. That will allow more room for roots until you do the chop in spring. Some of the roots will grow into the pot underneath but they can be cut in spring when you do the chop.
Plastic pots are not the only possible material. Plastic mesh, garden edging and many other materials are suitable. Anything that is stiff enough to stand up and hold soil but bendy enough to wrap into a circle round the trunk is suitable to retain soil and can be trimmed to the desired height is suitable.

The branches on this one have been allowed to grow long, assuming to assist the layer so there's plenty of excess to cut when you remove the new tree. I'd be cutting back at least half of the current branches when removing a layer like this. half may not be half of every branch. If there are superfluous branches removing entire branches counts toward the total removal and 'half' is just a guideline. Prune whatever you feel comfortable with and the tree will compensate by growing a little less or growing more roots until it is balanced again.
Great result with the new roots so far. Looks promising for the next stages.
 

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A low branch does not exclude the pot option. Plastic nursery pots can be cut to any height to fit anywhere. I would still see that as an option now - remove the bottom and enough height from a suitable sized (diameter) pot and split one side so it can be fitted round the trunk and new root ball. Then you can remove the plastic (leave the current moss and new roots as they are) put the pot in place and fill with soil. That will allow more room for roots until you do the chop in spring. Some of the roots will grow into the pot underneath but they can be cut in spring when you do the chop.
Plastic pots are not the only possible material. Plastic mesh, garden edging and many other materials are suitable. Anything that is stiff enough to stand up and hold soil but bendy enough to wrap into a circle round the trunk is suitable to retain soil and can be trimmed to the desired height is suitable.

The branches on this one have been allowed to grow long, assuming to assist the layer so there's plenty of excess to cut when you remove the new tree. I'd be cutting back at least half of the current branches when removing a layer like this. half may not be half of every branch. If there are superfluous branches removing entire branches counts toward the total removal and 'half' is just a guideline. Prune whatever you feel comfortable with and the tree will compensate by growing a little less or growing more roots until it is balanced again.
Great result with the new roots so far. Looks promising for the next stages.
Good idea, I’m sure to have a variety of pots in the garage. Plus it sounds like it is best to wait until the roots turn brown to separate the air layer or at least 10 weeks before first frost which arounds here means early Sept.
 

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OK, I dug out a plastic pot, made the necessary cutout for the trunk and slipped it in place to check the fit. I then removed the plastic wrapper and replaced the pot, securing it with several wraps of duck tape. It was sitting right on top of the soil so no need for any extra wire, etc. Finally I filled the pot around the rootball with my bonsai mix and gave it a good watering. I figure I’ll wait until I see roots coming out the bottom before I sever the trunk. I plan to keep the stub and surface root to see if it will push out some new growth, may get a second tree out of this!

19BFEE45-66E3-4C12-8549-7C16110FE967.jpeg
 

Maiden69

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Next time to make it easier, chop the sphagnum. I have a small Black and Decker food processor that I use for this purposes. It doesn't hinder the moss abilities at all. Just make sure you don't pulverize it. I used to use my soil sifter, but this keeps me from shredding my fingers...
 

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It was chopped in an old blender, just not real fine though.
 

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Well it has been a little over 3 weeks since my last update on this project. I had noticed that a few roots were coming out the bottom of the plastic pot so I decided it was time to do some surgery. After removing the old plastic pot I found a mass of roots had filled the bonsai soil that I had added last month. I then got out my little pruning saw and made the cut right at ground level. I filled a larger pot with some sphagnum packing it in around the rootball and added some bonsai soil on top. Hopefully the root in the old pot will send up new shoots and we’ll be off and running again! Here are a few pics.
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