Air Layering

[terryb]

- In between the top and bottom cut, how consistent do you need to be in the moss covering? Like, is 90% surface area coverage good enough? 95%? Or you really need to go over the top with the sphagnum and make sure you have extra coverage?

What @legoman_iac said. If you are going to the effort of air layering, you want to give it the best chance of success

- Sort of a follow on question from above, but is the idea with the sphagnum to: provide moisture to the trunk above the cut and provide moisture and a growing medium for the new roots. But I also want to know if it needs to act as a consistent bridge between the top and bottom cut?

The moss provides a constantly moist environment for the roots to grow and develop. It doesn't act as a bridge. In fact we discourage the bridging between the top and bottom cuts by scraping all the cambium off. If there is bridging, you won't get new roots.

- A couple of people mentioned holes for excess water to drain. I assume warmer months are better to start a layer as warmth = growth, but do you ever need to add moisture or is there a risk that the sphagnum could dry out?
- Because people mentioned holes for drainage, I assume it doesn't matter if the bottom and top cable ties are not super-tight?
- I've seen photos before of people using plastic potting tubs. Is it a good idea as an extra step; once there are a decent number of roots, to switch the bag out for a pot with a different growing medium, to allow the roots to continue to grow in a more open-air environment and then chop?

There are many ways to execute an air layer and what care is required will depend on how it is made. If you use an open pot or open-top bag of moss, you will need to make sure the medium stays moist. If you overwater with an open top bag, you will flood the developing roots, so drainage is required (pots have drainage holes). If your bag is sealed, and you squeezed the excess water out of the moss, then drainage is not required but you will need to keep an eye on the layer because as the roots form and take up water, the moss will dry out. You can wet it again with a syringe or something similar.

- I would think that for work-ability, it's better to chop as close to the top cut as possible. But is there any advice on how high up to make the cut? Is it better to leave an inch of the previous branch, or cut the branch somewhere in line with where the roots have grown down to or is it OK to make a concave cut to remove as much of the old branch as possible, providing plenty of space for new roots to grow?

The roots are usually fragile so I cut as high as I am comfortable with and then pot it up. Next repotting season, the roots will have strengthened and you can get in and remove the left over bit of trunk/branch at the base. You can continue to improve the roots and base at every repot

[SuperBonSaiyan]

I just did my first ever air layer! Hopefully it takes. It's on an olive tree and I painted the bark with rooting hormone.

I'm pretty excited to see whether roots form.

Wrapped in bubble wrap because I had that lying around.

[SuperBonSaiyan]

I've heard a few youtube videos say (wrt Japanese Maples) that one should wait until leaves have hardened off before air-layering.

What does this mean? How do I know when leaves have hardened off?

I'm quite new to horticulture in general... so does this just mean when the leaves are fully open? I have a few maples that are fully open now, but some others that haven't leafed out at all - so I was thinking to get a head start on those that are ready.

Thanks,
SBS

[Peter KB]

It means when the new “soft” leaves have grown for long enough to look like a normal darker coloured leaf

[Peter KB]

It means when the new “soft” leaves have grown for long enough to look like a normal darker coloured leaf

[SuperBonSaiyan]

It means when the new “soft” leaves have grown for long enough to look like a normal darker coloured leaf

All the leaves are different coloured though. Some are red, some green, some dark purple with green tinges.

Timing wise, would anything have hardened off by now, or would it be more like late spring?

[legoman_iac]

It means when the new “soft” leaves have grown for long enough to look like a normal darker coloured leaf

All the leaves are different coloured though. Some are red, some green, some dark purple with green tinges.

Timing wise, would anything have hardened off by now, or would it be more like late spring?

If you have a few trees, try it on one to start with. My trident maple worked, but started end of October. Think Japanese Maples can be a bit trickier then tridents.

[SuperBonSaiyan]

If you have a few trees, try it on one to start with. My trident maple worked, but started end of October. Think Japanese Maples can be a bit trickier then tridents.

I've heard tridents are notoriously difficult to air-layer. Did you do anything special to make it work?

I want to layer a whole bunch of them to make a forest.

[TimS]

It means when the new “soft” leaves have grown for long enough to look like a normal darker coloured leaf

All the leaves are different coloured though. Some are red, some green, some dark purple with green tinges.

Timing wise, would anything have hardened off by now, or would it be more like late spring?

If you have a few trees, try it on one to start with. My trident maple worked, but started end of October. Think Japanese Maples can be a bit trickier then tridents.

Interesting, I haven’t tried but heard tridents are harder to layer well than JM. I’ve found JM to be pretty much fool proof in terms of layer success

[Matt_W_NZ]

It means when the new “soft” leaves have grown for long enough to look like a normal darker coloured leaf

All the leaves are different coloured though. Some are red, some green, some dark purple with green tinges.

Timing wise, would anything have hardened off by now, or would it be more like late spring?

In my understanding, “Hardening off” generally means that point at which the leaves are fully grown and shift from focusing on growing to focusing on being energy producers for the tree. At this point the tree can push the root growth you want as its primary focus in the layer. If you airlayer earlier, you’re asking the tree to use its energy reserves from the previous year to both grow leaves and roots, which may be a hard ask depending on the branch you are airlayering.

For me in inner SE Melbourne, JMs harden off around mid October and I’ve always had success airlayering them and removing the airlayer by late January when they are dormant, perfect for potting up and giving them time to settle and grow through autumn.

Of course, for every technique there will be differing views. I saw people airlayering JMs and others last weekend, well before the leaves had even pushed on the plants they were airlayering, they said that timing was fine. Will be interested to see the results.


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[Stevie_B]

Great thread.
I'm very interested in Oz natives in particular the mels, calistamons and leptos.

So with natives in mind but not exclusively, are there any tree species that people have found won't layer? I would assume so long as you can get through the cambium ok it should root. Paperbarks would be a little problematic i guess.

[SuperBonSaiyan]

So I just came across this in a video - could be useful if anyone had the same question I did in terms of leaves hardening off.

https://youtu.be/ANrC2TGL72U?t=640

@ 10:40 he describes what the leaves hardening off looks like.

It made me realise that none of my leaves have hardened off - they're all still rather floopy.

[TimIAm]

I put this layer up on the 22nd of September. A few days ago I checked and it had a few roots. Today I check and the number of roots has exploded!

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I assumed now is a good time to take it off rather than packing in more material. One that I started 2 weeks prior to this hasn't put out any roots and has only just started to callous at the base of the top cut.

I noticed this tree was about to put out leaves. It's a peach and when it puts out leaves it does it all in one go. So, I thought now would be a good growing period to put the layer on.

IMG_1505.JPG

I'm keeping most of the sphagnum on as I put it into a pot. I don't see any harm in doing this now. Next step will be to re-do the cut higher up and at that time I will clear out the sphagnum, change the potting medium and put it in a training pot.

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For some reason there were significantly more roots on one side. I'm still pondering why this may be. There are a few likely reasons (sun, less space/more compact on that side, moisture). I will think about this next time I approach a layer to see if I can get a more balanced result.

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For now it's just going to be regular premium potting mix and letting those roots grow out and likely nothing more until next growing season.

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The only question I have left is should I cut it back or wait until next year? It's almost 2 metres in height.

Thanks everyone who took time to answer my first round of questions. I'm quite confident it should be good from here. So thanks for helping me get my 1st successful air layer!

[shibui]

I would bet that more roots on the side that has the live trunk. Sap takes the shortest track from leaves to roots so there will be a lot more sap, nutrients, food, energy on the side with the live branch. Growth drives roots.

Good call to leave the sphagnum in situ for now. New roots are incredibly fragile. They'll be much better attached next year and you can comb out any remaining sphagnum and cut back the umbillical then.

Plenty of branches/leaves will make roots faster but I often reduce branches a bit at transplant if I think there's too many branches for the roots. Leave major reduction for next year when the roots have grown stronger.

[TimIAm]

Sap takes the shortest track from leaves to roots so there will be a lot more sap, nutrients, food, energy on the side with the live branch.

That's really interesting. Is it possible on something like an elm that budding then is more likely to occur on a side which already has more branches? Is that why you end up having to wait longer for a branch in a bare patch? Just thinking...

I kept the full height of the original branch because I knew that it was just about to leaf out. I didn't want to disrupt what was about to happen growth wise by pruning as I was starting the layer because all of the buds were in place.

The problem (I think) with pruning now is there are not many leaves. This branch was semi-shaded and majority of leaves are at the top. I'm guessing because there are not a lot of leaves to keep alive there is less issue with it being thirsty (a guess)?

I do know if it survives summer I can prune back super hard just as spring hits and it will bud all over. This tree responds really well to hard pruning and I get plenty of fruit. There is growth on top, in the middle and a bit near the base. What I don't know is what is the best approach (with pruning) to help it survive??