This was our first year growing cannas; and I just fell in love with these plants. They took everything that Oklahoma could throw at them and kept on blooming! I dug most of the tubers (left a few - well mulched- next to the house) and stored them in brown paper bags in a basement. I checked on them last week and the look dry and shriveled! Are they still viable? Any help appreciated!
I grew for years Canna, the President. They are supposed to be stored in a cool place in peaty soil, or somewhere cool. We always had them in the front part of an unheated basement space. Because they always had some moisture and the coolness of the area, they never shriveled up. With zone 6, you are not that far away from planting them in the Spring. I would soak them in a little warm water, then place in some slightly damp peat moss. Even if they start growing in the house, it will be ok when the time comes to plant them. Mine sometimes started growing in the cold area and had stems/eyes about 1 foot. It may save the bulbs and they still may be viable. I would certainly try..they are tough plants, as you found out. Good luck :)
I've grown canna here in Zone 6 for years. I dig them up in late fall and put in grocery bags. As dry as they look the following spring, I just plant them again after frost and they come back double. Believe me, if they could be killed I am the one to do it!