Bought the parent tree this spring. Repotted it and started this air layer at about the same time. Harvested this air layer about a month ago and potted in a mesh bottom tray. Here it is in fall 2021:
It seemed to be about the same as layering most of the other cultivars that I’ve tried. The roots looked a little unusual compared with other maples’ roots, but they grew with similar vigor.
I did this layer by girdling the trunk with a grafting knife, removing a ring of bark, scraping off the cambium layer underneath, and wrapping tightly in moist sphagnum moss. I poked some drainage holes through the plastic bag covering the sphagnum, so excess water could drain out the bottom. I also left a bit of an opening at the top so I could water the layer.