Keeping you yacon crown viable through the winter (applies only to areas where the ground freezes).
1. Dig the entire plant when a freeze has killed the top, but before the ground freezes. Cut back the tops to the ground. Using a garden fork, starting loosening the soil a foot away from the center of the plant. Complete the entire circle around the plant.
2. With the soil loosened, pick a side and shove the garden fork as far beneath the plant as you can. Lever the crown up out of the ground using multiple jerking steps to cause the loosened soil to break away and fall from the tubers and crown.
3. Lift the entire crown into a wheelbarrow and take to a water hose to rinse the remaining soil away from the plant.
4. With a sharp knife, separate the "sweet potato-shaped" tubers away from the crown. These will vary in size from a golf ball to a rather large sweet potato. These are the edible parts.
5. Place the crown in a bucket/bin with slightly moist peat moss (wood chips, decayed straw, etc) and cover. Place the container is a cool place (but not capable of freezing) until about 6 weeks before last frost date in your area.
In spring, treat the crown as mentioned earlier in this thread.