I am wondering if on a rough bark cultivar, will the bark go past the graft or will it forever be Arakawa top and Acer palmatum bottom. Here is the tree I’m curious about. I have taken dozens of cuttings in the past so it has served it’s purpose, but will it ever be a bonsai?
The bark type will change at the graft so you always have a smoother, lower trunk. It looks like the upper trunk has not barked up very much so you can probably airlayer above the graft. On something like this, I often build a mesh cage a few inches from the trunk that extends well above the airlayer site, fill the bottom with very coarse soil like 1/2" lava/pumice, put down a layer of weed block cloth, and then use more common airlayering soil above the cloth. This is really nice and stable so the roots are not damaged as they emerge.
Thank you. . Is there an ideal time for this action ?
Yes, after the new leaves harden off which is typically in late May to early June in the northern hemisphere. Make sure to familiarize yourself with airlayering since it is easy to make a mistake and not have it work (I speak from experience).