I have a lot of colchicums that thrive here in Zone 6/7. Among them are cultivars of C. autumnale as well as C. agrippinum, C. bivonae, and C. speciosum. They are all listed as being hardy in Zone 4 if the drainage is good. Mine grow with the shoulders of the bulbs only 2-3 inches below the soil. If one wanted to grow them in Zone 4 or colder, would deeper planting make them less vulnerable to the cold? Would they tolerate deeper planting? Advice would be appreciated, Best wishes, Dell Dell Sherk, SE Pennsylvania, USA _______________________________________________ pbs mailing list pbs@lists.ibiblio.org http://pacificbulbsociety.org/list.php http://pacificbulbsociety.org/pbswiki/