Hi, I have not been on this forum for sometime and just came across this post. I have been storing various bulbs and tubers for several years, and I find the best way to store them is in moist potting soil kept in the basement over winter. I cut off the plant, let the tubers dry a bit so all the dirt can be shaken off and then pot them up. If they are grown in pots, I just cut the stem off, withhold water, and transfer to my basement (dark and fairly cool). I use this method for dahlias, cannas, begonias, vodoo lily, tube roses, oxalis,and sweet potatoes. I have also stored sweet potato tubers in saw dust, but that ws many years ago. Hope this helps.