Canna lilies are perennial plants and will produce flowers every year and multiply. In the south, canna bulbs are not lifted out of the ground, but in USDA hardiness zones 1 through 6, you will need to lift the bulbs and store them for the winter. Wet, soggy soil in the winter will cause the bulbs to rot, if left in the ground.
Gently dig the bulbs up when the stalks become yellow in late fall or just after the first frost. Leave the bulbs in clumps or divide them at this time. Some gardeners prefer to separate the bulbs while storing, instead of in the spring before planting.
Rinse the bulbs with water to remove the soil. Hang the bulbs by the stalks of the plant so that the bulbs will absorb the last of the moisture from the stalk and leaves and begin dormancy. Let the bulbs hang for one week, take them down and cut the stalks off.
Do not store any soft, diseased or damaged bulbs. Discard any bulbs that look less than healthy. Dust the bulbs with sulfur to control mites, black spot and mildew and place the bulbs in a terra cotta pot, bulb tray or plastic bag with small holes throughout the bag. Lay the bulbs in a single layer and cover with peat moss or vermiculite. Leave spaces between the bulbs, as air circulation is essential. Do not wet the peat moss for canna bulbs. They require dry soil.
Store the canna bulbs in a cool, dark room with temperature around 50 to 55 degrees F. Basements, garages and sheds are ideal rooms. Do not allow the bulbs to freeze. Check the bulbs each month for mildew, fungus and/or mites and rodent damage. Remove any damaged bulbs and move or replace the storage container. Do not let the peat moss become wet. Replace any wet peat moss or vermiculite with dry.
Bring the bulbs out approximately four weeks before the last frost and plant in pots indoors. Divide any bulb groupings into individual bulbs, if you did not divide them before storage. By dividing the bulbs, you can plant the canna bulbs in more areas.
Wait to plant the bulbs directly outside after the last frost or when the ground temperature reaches 40 degrees F. The bulbs will be shriveled due to the dormant period, but will fill out and grow well.