I think Ellen is right about the snow cover protecting C. graecum. I had a few volunteers outside here for about 3 years. I eventually saw a single flower but they went away completely as soon as we had a really cold spell without snow cover. J. John T Lonsdale PhD 407 Edgewood Drive, Exton, Pennsylvania 19341, USA Home: 610 594 9232 Cell: 484 678 9856 Fax: 801 327 1266 Visit "Edgewood" - The Lonsdale Garden at http://www.edgewoodgardens.net/ USDA Zone 6b