Let it dry down, let the frost kill it back, then move the container into the basement or indoors and keep it dry all winter. I actually over-wintered one in my unheated garage this winter and it was fine in the spring. .... offering that as a point of incredulity - not a recommendation. I was amazed to see the little sprouts sticking out of the soil in May. Root prune & repot in early spring - keep soil barely damp until it starts pushing growth.

Al