Dear Robert; Here in Zone 5/6 Crinums are usually mulched with dry oak leaves and non-woven fabric 'tacked' down to keep leaves in place. They usually do not die back very far below 'leaf line'. Of course depends on the species/cultivar. Jim W. -- Dr. James W. Waddick 8871 NW Brostrom Rd. Kansas City Missouri 64152-2711 USA Ph. 816-746-1949 Zone 5 Record low -23F Summer 100F +