@polymerous The rootball should be very tight, so there should be little root disturbance when you remove it from the tree pot. Just plunk it, undisturbed in a larger pot, and keep it wet for a while. (make sure you concentrate the water at the existing root ball)
You might have to go larger than a #2 though, because of the current height of the tree pot. Are you using the thin, black plastic, 4" square tree pots they call "short ones"?
