Divide the tubers and rhizomes in the fall. Remove the soil from the root system.
Choose blemish free tubers and discard any rotten segments. Separate each tuber (a type of root system) and rhizomes, ensuring there are eyes or buds evident on each division. This is where new foliage will emerge. Cutaway these new tubers from the parent plant's roots with a sterilized sharp knife. Cut the rhizomes in sections with a couple eye buds on each division.
When replanting, set the tuber pointy side and the eyes of the rhizomes facing upward. Cover with rich, nutrient soil (add amendments to heavy soil in the garden). Keep moist to soggy consistently. Do not let the soil dry out. Wait until the plant is producing new green leaves before starting to fertilize.