OlBlue

I Don't know anything about S. Cal. weather. Folks down in S. Fla. zone 10. Can't seem to keep Jap. Maples alive over a couple of years,because they don't have enough winter cold to put the plant into dormancey. In N. Fla. I put potted maples in a shady spot and mulch around the pots , trying to keep the roots as evenly cool as possible. Otherwise after their fall leaf drop they will bud out, every warm spell ,then the next freeze kills the tender leaves. Commercial nurseries can't bother ( they lose trees though ) . trees in the ground seem to have no problem. Anyway putting your potted tree in the cool shade sure won't hurt it , and may help it. I would not defoliate it at this time of year. Try to keep it a little dryer in the winter,it won't bud out as fast. Wellcome to Japanese Maples