Canna lilies are left in the ground in regions where temperatures do not fall below 20 degrees Fahrenheit. In regions with very cold winters, the rhizomes are dug up and stored in a growing medium until spring.
After a frost that kills the plant's leaves, the flowering stem is cut off 4 to 6 inches above ground level, and the rhizome is dug up with a gardening fork. The rhizome is allowed to dry for several days in an area with temperatures above freezing before being placed in a container with vermiculite or peat moss. It is replanted when temperatures are above freezing.