Cannas are tropical plants native to Asia and South America. They have broad leaves that slowly unfold as the plant emerges from the ground and showy flowers in a variety of colors, including yellow, pink and coral. While the rhizomes, which are the bulbous roots, can survive cool weather, they are unable to handle the constant freezes and thaws of winter. If you live in USDA hardiness zone 7 or below, you need to dig the rhizomes in fall and store them until it's time for replanting in spring.
Cut back the foliage using a sharp knife to within 4 to 6 inches of the soil. This should be done three or four days after the first hard freeze of the fall season.
Dig the rhizomes up using a garden spade. Be very cautious not to damage the roots. Flip the rhizomes over and allow them to dry for several hours.
Apply a fungicide as directed on the package to help prevent disease while the rhizomes are in storage.
Place the rhizomes into mesh bags and move to a cool, dry location. Ideal temperatures range between 40 to 50 degrees Fahrenheit. Examine the roots regularly and mist with water if they begin to look dry.
Move the cannas back to the yard or garden in spring, after all danger of frost has passed for your region.