I dig mine up, cut stems off about 1" from tuber - Let them dry out - Then I wrap in paper place them in a cardboard box then into a cool dry place (Frost Free) I put mine in the garage - until I start them up again next year.

Or you can store them in dry compost or sand. Keep mice away! Start them into growth early as they can take ages to get going.

Thanks both - I will try both suggestions!