I just leave most of my cannas in the ground over the winter, however, a few that I want to move around the yard are in five gallon pots. one of them, also a Pretoria, started out as a finger sized rhizome I got in a trade. I left it outside in a protected area until two weeks ago. Sometimes containerized cannas are hard to divide because the rhizomes can get really compressed in such a confined area. Anyway, I was able to get twenty five really good divisions which I potted up into one gallon containers. I then put them inside in a warm spot and they all sprouted within a week. They will spend the next three weeks out in the greenhouse. Some I will plant out, some I will trade.

As long as your container didn't freeze through over the winter or stay excessively wet, your canna should be fine. If possible in zone seven or eight the ground is always the best place to overwinter cannas.

Bill

you will be able to tell by looking at the rizome.It should feel firm not sqiushy and should not be brownish,but sometimes some brownish will be on outside but not all the way through and feel firm.they are pretty tough.I've had them in buckets that got rain and freezed briefly and they survived,,,,but thats in a zone 8b TX I've seen them survive inground in zone 6.if were in pots and snowed the snow would have helped protect them.you could bring in and divide and pot up and see what sprouts.