Having rescued two skinny, 4-foot tall vine maples from a local hardware store for a very small price, I'm deciding what to do with them. They are marked "zone 6." Has anyone been successful with planting them in the ground in zone 5? I will probably use them for bonsai, and I'd like to have the trunks a little thicker. Do any of you have links for good acer circinatum bonsai photos?