Dahlias?

I have an outbuilding that stays reasonably cool and frost free. I store onions hung up in it. For the dahlias, I put a big piece of cardboard on the floor and pack them together on it. Some have quite a bit of soil round the tubers. I probably check them once a month. If any small ones are looking too dry, I pot them up in old compost. In the spring, I put them in a greenhouse in some bread crates I've acquired and cover with a mix of soil and old compost. When they sprout, I sometimes take cuttings or just plant them out.