Dahlias?

I make sure my tubers are thoroughly dried out. Dig up and dry upside down in the greenhouse. When dry, brush off the mud. I wrap in newspapers and store in boxes. Any sign of wet and lots can rot off. If you have enough - storing in perlite/vermiculite is a good option.
My Aga when taking it out was filled with vermiculite. I've used that to store some of mine. They were perfect when I took them out. Unfortunately the newspaper wrapped ones got mice in!