From my reading, the successful layers with dogwoods were all ground layers. I'm going to give it a shot with my Not a Contest tree this year to try saving its two top trunks.
Cornus Florida...
Airlayer job...
What do you think?
Anyone out there ever try before???
It's a yard tree at a friend's house...
Thinking of about a one inch thick branch.
I'm on my third year of trying. However, I made quite a few mistakes as it was my first attempt. The layer branch didn't overwinter well this year. I think I probably put it to rest with still too much moisture and it appears to have rotted. I'll let it play out this year and see what happens. I think if you do it carefully and use strong rooting hormone it may go. Mine seems to have tried. https://www.bonsainut.com/threads/dogwood-air-layer-attempt-round-two.29913/