I don't see winter hardiness as the real issue with tree dahlias. When I grew them years ago (not far from where Will Aley lived back then) the more limiting factor was their bloom time: they bloomed so late that they got frozen every time. And providing frost protection for something eight or nine feet high wasn't on my "to do" list. Jim McKenneyMontgomery County, Maryland, USA, USDA zone 7, where not much has changed in the last two weeks. _______________________________________________ pbs mailing list pbs@lists.pacificbulbsociety.net http://lists.pacificbulbsociety.net/cgi-bin/…