I have never had much luck overwintering tenders potted up. Usually I dig em up (I have Elephant Ear and dahlias, Canna), knock off the dirt, trim away the dead foliage, then pack them in cardboard boxes filled with raked up autumn leaves. I usually wait as late as possible to do this and I usually try to get them back out and either potted or planted as early as i can. i was neglectful this spring and I paid the price: nearly lost my Elephant ears and did lose a number of dahlias.
