A couple of months ago I managed to have a look at the new roots growing on this very large Japanese Maple garden tree that I had ground layered two years ago here.
Evidence of new roots
Wooden box removed and rootball undercut
Plenty of new root beginning to thicken. These were spread and left to extend and thicken.
No new roots on this side. Older thicker roots were trimmed around the whole tree.
The bare side was cut again and pasted with rooting hormone. Tree replanted with free draining soil mix and covered.
Back in the flower bed for another two years.