Hi Keith,
If your canna is potted you can just store it as is in the pot. I grow all my cannas in containers and haul them in for the winter; I have found they store better that way. I bring mine in after the frost hits the foliage but it's not necessary to do that. You could just bring it in now after cutting off the foliage, if you so choose. They are best stored in a cooler part of the house such as the basement. If you do wish to dig it up you can store them in slightly moist peat moss or the like. I've also stored bigger clumps with soil attached in garbage bags and they've done well. In any case repot with fresh soil in the spring and start them into growth again.
