One other point that I forgot to mention... In the late 1990s I saw Pinellia cordata growing quite happily in several gardens in the Ann Arbor, Michigan area, which is certainly a subzero F region. These appeared to be established clumps as opposed to spring replants. However, the leaf size was smaller and had less variegation than the Yamazaki clone, so it may have been a hardier strain. Most of the plants I have seen in gardens or nurseries in Japan appeared to be the small leafed type. And out of thousands of flowers, I have only had one set seed. The special gnat that does the pollinating must have been around that year. --Roy