I have a new JM that is a specimen sized. Grown in the nursery in a pot too happy on a drip emitter... Many fibrous roots all. I should aim to remove at least plant it 2-3 inches, removing said fiberous roots. I can hold off planting till next spring and do a -root prune- before then How -stressful- is it if I just plant it high now....and let those roots dry off on its own.
As the season advances, it becomes more and more stressful. If the roots are still growing, it's still OK. I do a small amount of potting in September, but no longer in October: those maples had a very poor success rate. If needed, slip pot now, the repot with root pruning before bud-break, Otherwise, safer to wait.
