Dell asked, >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 4Â or colder, would deeper planting >make them less vulnerable to the cold? Would they tolerate deeper planting? I don't plant my colchicums very deep, but once I rescued some C. x agrippinum (which turned out to be a different clone from the one usually grown) from an old Portland garden where they had become buried as much as 18 inches (about 50 cm) deep by repeated floods. They were thin and elongated, but they were still flowering, and when I got them into the garden they flourished. Jane McGary Portland, Oregon, USA