Wait until the first frost has blackened the foliage
Cut the stems down to a few inches above the tubers
Carefully dig up the clump with a fork or spade
Gently shake off excess soil
Rinse or brush off remaining dirt
Let the tubers dry in a cool, airy place for several days
Remove any damaged, rotten, or diseased tubers
Divide the clump if desired, making sure each division has a viable crown
Dust cut surfaces with sulfur or fungicide if needed
Place tubers in a box, crate, or paper bag
Pack them in dry peat moss, vermiculite, sawdust, or wood shavings
Store them so they do not touch each other
Keep them in a dark, cool, frost-free location
Maintain storage temperature around 40 to 50°F
Check tubers periodically for rot or shriveling
Mist lightly if they become overly shriveled
Repack any tubers that show signs of moisture or decay
Replant in spring after the danger of frost has passed