Just before the first frost (when I don't forget), I cut the stems to about 8 inches, then dig out the roots and put them into a double plastic bag. I add a bit of soil to cover the roots and water them in. The double plastic bag saves messes here. Not too much water, just to dampen all the soil and the fleshy roots. Then I put the bag in the corner of the (frostfree) conservatory, tie the handles to keep the moisture in. A bit of water now and then (not much) and they will shoot again in spring. There are usually several shoots from every stem, but some roots don't make it.
I think it is worthwhile doing. It's apparently a Victorian thing.