Air layering question with crab apple tree

Hoping for some feedback. I’m relatively new to bonsai and air layered a couple small branches on a crab apple tree on May 23rd. Within a couple weeks one of the branches died [above] the air layer. Up until the last week the 2nd air layer was doing fine. While the non-air layered branches are doing fine and actually thriving, the leaves are started to curl up and some leaves yellowing on my 2nd air layer. Seems I’m now going to lose 2nd air layer as well. I’m in Chicago and the past week has been very hot with high heat indexes. Can air layer be stressed in trying to grow roots with high temps? As I understand the air layer stays 3 months. It has been fine for 9 weeks, but looking sick now. I have it in shade now, but I’m not optimistic. Suggestions and feedback please? I utilized the correct tool to remove bark, utilized root gel, Spaghnum, etc. Much thanks everyone

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Pic of leaves…

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What was your airlayering process- technique?


I can see foil so I’m assuming there is a bag full of sphagnum under that. Have you checked the layer for moisture levels/ roots? If there are a lot of roots that have indeed developed, they’ll be in need of more water, particularly if it has been hot. The foil “ball” doesn’t look huge so water will definitely be something to watch. To me it looks like it may have dried out. Keeping it out of direct sun right now (at least during the hottest parts of the day) seems like a good idea.


…thank you. Basically air layer tool to remove outer bark, root gel, sandwich bag packed with Spaghnum cut into 1-2" piece soaked in water, then wrapped in aluminum foil. Coated wire top and bottom with opening on top to allow water in. I’ve checked Spaghnum all along and it as been most, so I’m puzzled…

Ryceman, thank you. I’ve checked along the way and the Spaghnum ball has been moist. I’ve not dug deeper into the Spaghnum to visualize the roots only for fear I’d damage or disturb too much.

I had an issue this year with the very same problem, albeit on a Japanese Hornbeam.
I’ve done many air layers and haven’t had this issue before, but there’s still hope - don’t feel too bad yet.

I cut a 2" ring, used spaghnum, kept it in shade, made sure there was plenty of top growth to fuel the new root development etc…but I think my mistake was with that last point.

I’m in SE MI and similarly to you guys, we have had a ton of heat in late June/July. My layer was doing great and was about 5 weeks in when the heat really hit. Within two days the portion above the layer rapidly wilted, leaves yellowed and dropped, etc. But, when I checked the layer, there was a lot of root development. What I believe happened is that I kept a lot of top growth to help feed/push the new roots and once those roots were out, the proportion of foliage to roots was too far off. The heat generated a great deal of transpiration that the new roots simply couldn’t replenish. So I panicked.

My advice is to check how many roots have developed, if there is a fair amount of roots, separate the layer. At the same time you plant that new piece, cut it back hard to viable buds.

I did this with my Japanese Hornbeam layer and it’s not skipping a beat. Currently pushing new growth and sitting happily in the shade. I can’t guarantee your success rate but leaving it attached at this point isn’t helping it much if new roots have already pushed. Also, you may as well do the scratch test to see if those layers have moved past the point of saving - give the bark a scratch with your fingernail and see if it’s green underneath. If it isn’t, they’re likely too far gone. If it is - cross your fingers and take it as a learning experience. Good luck man!

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Ray, huge thanks to a fellow Michigander. If your zone 6 you must be up the coast a little(?) Anyway, I’m taking to an instructor Saturday, but will do the scratch test in the interim. If there are enough roots, I’ll separate. How long had your JH been air layered when you separated it? Overall, I mainly want to know if there’s anything I should do different for future air layers. I’m glad you had a good outcome with your Japanese Hornbeam!


No problem!
Sorry for such a late response to your questions - how did the visit with your instructor go?
My JH would have been separated around 5 1/2 weeks. I was surprised by the amount of roots when I checked them but attribute that to the heat/humidity we had been experiencing.

One thing I am going to do on future layers is to try to time the removal of some of the foliage above the layer with the development of new roots. I do not think I would have run in to issues had the heat not hit so fast but knowing now that I am able to reduce, and even separate, I will plan for that if the weather is changing rapidly.

I hope your crab is coming along and makes it through!

Thanks for asking! I was told that I air layered too much. In other words, and you noted this in your original response, I had too much foliage above the air layer. Oh well, lesson learned. My instructor recommended I wait until end of this month. Scratch test revealed green. Anyway, thanks again for your feedback and consideration…