Cut the leaves back after the first frost when the foliage turns yellow. If you are in a cooler zone (3-7), remove the rhizomes from the soil with an inch of stem attached. Knock off all the soil and lay them on newspaper in a dry place for a week. Do not wet or wash the rhizomes. Sprinkle them with powdered sulfur to protect against fungi while they're in dormancy. Lay on a single layer screen or in a mesh bag so air can circulate around them. Store the rhizomes at 50°F-60°F. When all chance of frost has passed in the spring, plant in the garden at a depth of 3 to 4 inches deep and 12 to 18 inches apart after the last frost in your planting zone. Place your rhizomes in a horizontal position, so the eyes are facing upward. Add compost or soil conditioners and mix in with the native soil.. Depending on the warmth of the soil, it usually takes 60 days to bloom. If growing in a planter container, use a well-draining potting soil with perlite to aerate the soil. Add amendments to clay soils in the garden to aerate the soil and allow for good drainage.