Hi, Jim. I know that the top freezes. I don't know whether the tuber -- corm -- underground storage organ freezes. Once they are damaged by cold, the leaves deliquesce, mineralize, become compost. They might freeze and thaw a few times in a short period, but they are gone quite soon. They don't hang on all winter. >Did you mean that > the deeply planted corms/tubers (more about this in a separate post) do > not > freeze? Surely the foliage freezes repeatedly in a normal winter?