I’m looking to do my first air layer to harvest a tree from the top of my large collected field maple (acer campestre).
I wave been growing it in the wooden box for over 2 years and is growing healthy. It is now in an energy positive state so I am going for it.
My question is what is best. A fixed pot suspended at the correct place filled with the appropriate sized acadama and dressed with a thin layer of sphagnum moss?
Or the plastic wrap with the sphagnum moss as the growing medium.
I airlayered a 2.5 cm A. campestre a couple of weeks ago and used an open top plastic bag covered in foil with top dressing. I also a smaller A palmatum and slightly larger C atantica ‘glauca’ and used the pot approach. Obviously too soon to see which works better and a not very well controlled experiment.
I found the pots to be far easier to do on the near vertical trunks I did. I cut pot down the side and across the bottom. I then cut out a circle the size of the trunk below the airlayer including the bark. I wrapped a heavy aluminum wire around the barked trunk to serve as a support for the pot and taped it closed in place. I held it in the correct orientation while I filled it with media (50/50 1-3 mm Akadama and pumice) and it was very stable without any guy wires above.
Thanks Marty, I am thinking plastic wrap for smaller diameter and pot with larger diameter, but still unsure. I have to make my mind up as I am doing it today because I have the time and the weather looks good here in Wales .
Plastic wrap is a solid approach because it creates a sealed environment, so you don’t need to water it during the rooting period. Just make sure the moss you use is moist (damp, not overly saturated) and not packed overly tight. Using a pot is fine, but it would be open to the air and thus would require watering.
From my research online, sphagnum seems to be far and away the preferred rooting medium. After that, you also see many using regular garden soil (heavily organic), again, not overly saturated with water. I personally would not use akadama or pumice for the purpose of establishing roots. Everything I’ve learned about these volcanic substrates indicates that they are best-used for improving/maintaining/stabilizing strong existing bonsai root systems. Conversely, everything I’ve read about getting plants started (ie, growing new roots) indicates that organic substrates (sphagnum, peat moss, compost, etc) are superior.
But it sounds like you’ve decided on the plastic wrap & moss approach, which is solid and well-established. Good luck!
My vote would be for a pot. My last three air layers were using the moss / plastic wrap / foil method and none of them took. I believe part of this was timing but I think it had to deal more with improper oxygen / water balance in the wrap. Next time around it’ll be pots for me for sure.
Although pots might be a chore in regards to watering - I think the likelihood of success is higher. You’re going to be moving more water and oxygen through the wound which in my opinion seems ideal.
My wrapper layers all ended up being too soggy or too dry - it was very difficult to get the right amount of moisture - especially during the sizzling summer months.
Thanks for the advice both, I think you guys illustrate why I was torn , but thanks for sharing your experiences.
I am grasping at Ryan’s comments in the air layering stream that solid technique goes a long way and that the time I took today will give me a fighting chance
I will try to, a bit concerned it’s staying too wet at the moment I left the top open to add water if and when needed but it hasn’t stopped raining since. Typical uk I suppose .
I just noticed you have a collar of wire at the top of your air layer. Do you have a source for this technique? I noticed, in one of Ryan’s air layering videos in the library, that he had a similar wire collar around the air layer of a hornbeam. The hornbeam had very poor results, only putting out a few tiny roots.
I imagine the collar is an attempt to ensure the cambium doesn’t reconnect, but it seems like overkill to me, and might even contribute to negative results. None of the dozen-or-so videos I’ve seen on air layering used this kind of wire collar, except for the hornbeam video mentioned above.
No other source than Ryan, which is good enough for me. A bit of blind faith in the main man I suppose . The way I saw it (multiple times ) is that the collar of wire was to make the roots that come out, buttress a little from the start. I believe the hornbeam air layer didn’t go ideally and needed to be done for a second time because the cambium breached the gap in a few small places?
I see, I had only watched the “air layer separation” vidoes, not the first one where he actually cut the tree and set it up. I just watched Ryan’s explanation in that video, and I guess it makes sense. It just seems like the tree performed really poorly, both in the first reveal and in the follow-up (never producing more than three root sites around the entire perimeter). The wire collar just jumps out for me as a foreign element.
There is a method of air layering called the “tourniquet method,” where a wire is tightened far more tightly than Ryan’s wire, restricting the flow of resources in the trunk. But this method doesn’t involve also cutting a ring around the trunk. Here’s an explanation of the two distinct methods: LINK.
I’d love to hear others’ experiences using a wire to attempt to create “buttressing” of the callous, as Ryan did in the video (LINK).
You can actually add a plastic wrap on top of a pot with mineral substrate if you’re not sure you’ll be able to water it often. I did it a few years back to air layer a 4" diameter chunk of norway maple, using a 2 gallons nursery pot and a trash bag. The advantage of the mineral substrate is that it’s really trivial to repot the tree in the spring following separation.
A peat moss and lava mix would probably give very good results thanks to the added retention.
Wrapping/sealing with plastic seems like a no-brainer to me. As long as you start with a damp, not-overly-saturated environment, sealing it will ensure the environment maintains a good balance of water and oxygen for as long it remains sealed.
When the tree produces roots and starts to use the oxygen and water from in the sealed plastic wrap wouldn’t it either tip the balance in favour of the water or just run out of one or the other? I’m not to sure, just asking as I said this is my first try at this an only been learning bonsai for about 5 years which I know in the grand scheme of things is not very long.
Most of the youtube tutorials for air layering I’ve seen completely seal the air layer environment. At most, they put a couple of tiny knife-pokes in the bottom of the seal to ensure water can’t penetrate and saturate/drown the medium. A lot of the tutorials are actually farmers or nursery operators, so their livelihood actually depends on the success of these techniques. I’d recommend searching “air layer” on youtube and just watching as many videos as you can.
Occasionally, I’ve seen a dry-ish medium when they open the air layer, but that’s because they’ve grown tons of roots that have drunk most of the water in the sealed environment. But the roots are still happy and healthy.
The canopy is still getting the vast majority of its water from the existing root base in the ground. The water in the air layer medium is only being taken up to sustain the tiny roots the tree grows into that medium. If there ceases to be water there, I think the tree would just pause growing those new roots; I think it would take an extremely long time for an initially moist, sealed air layer environment to become completely dry, because it’s attached/adjacent to the open xylem of a living tree, which is constantly transporting moisture to the canopy and, thus, is humid.
Again, I’d just recommend watching as many videos on the subject as possible. After a certain point, I feel like the elements of the technique become sort of intuitive. I only began practicing bonsai earlier this year. I initiated my first air layer on a ficus a few weeks ago, and am already seeing new roots in the clear, sealed plastic air layer environment.
However their line of work never bare roots the separated layer, they will only slip-pot up or place in the field for growing. It’s the same issue with the cuttings in peat discs… they do strike easily but the cleanup at transplant time is a pain and you risk losing a sizeable portion of your fresh new roots. So now my cuttings are made in the smallest particles left from sieving pumice, lava and akadama. I sometimes even add some sand on top.
I’ve been propagating for bonsai through cuttings and air layers since about 2005 or 2006… granted there was a break between 2014 and 2019. I got out of bonsai, relocated to a different country then got into bonsai again. This year I’ve got air layers on a few crab apples, a bunch of 4"+ diameter olives, some plums, some spindle trees, a field elm, a pair of yews and small leaved limes.
Ficus will root readily in pretty much any mix. Most ficus will even emit roots without any soil in the bag, you can simply loosely wrap some saran around the trunk with a wide opening just above the soil… the increased humidity will lead to the emission of roots all along the covered section. That’s actually one of the techniques to turn an ugly “ginseng” into a banyan style ficus.
Thanks gentleman, all useful info for next time. I generally listen to Ryan as that’s what I’m paying my fee for, but I also watch what Peter Warren puts out and I have had his book for a while just to get a UK angle on things, the main reason I increased the cut out area to 1.5 times the trunk thickness. A lot of comments from Ryan about how vigorous a trident maple was and I was wary of how a field maple would react which was another reason for the wire collar. I have seen a few YouTube videos from the very experienced chap who runs Herons Bonsai, who does go with the straight plastic wrap and moss on his acer layers. Fingers crossed mine gives me something.
I am hoping to get another 2 trees out of what is remaining from this large field collection so any improvement suggestions for next years technique while be happily listened to. (Unless what I have done this year works perfectly, which I suppose is unlikely being my first time, in which case I would just do the same again I suppose) .
Thanks for your input .
Thanks, Michael, for sharing a bit of your expertise! Experienced people like you make this forum so amazing. Good luck with this year’s air layers, both of you!
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. The way I saw it (multiple times 
) is that the collar of wire was to make the roots that come out, buttress a little from the start. I believe the hornbeam air layer didn’t go ideally and needed to be done for a second time because the cambium breached the gap in a few small places?