I have cannas that someone gave me and they're still in the basement. I don't plant them out until after the last frost. I think yours should be fine until then. Don't fertilize and keep them in a low light area.

Okay, thanks. Will stick them in the basement. Think I should open the bag and let them breathe or keep it sealed?

or in a cold garage. I've cannas naturally grow in spring despite being overwitnered in the basement and in the dark. The usual technique is to keep them in slightly moist newspapers loosely or peat through out winter. I suppose this is the same treatment you would give them now. Watch out for rot.