It’s tough to find a flower that offers as many bright and varied colors as the canna lily. But while these beauties are not dainty, they are sensitive to the cold. If you live in growing zone 7 or lower, your canna bulb will freeze to death if left in the ground over winter. To keep your canna lilies alive next season, dig them up at the end of the season after the first frost has killed of their frost-killed foliage has become dried and shriveled.
Use a garden fork to loosen the soil around the canna bulb. Take care not to damage the bulb with the tines of your fork. Start a few inches away from the base of the plant, stick the fork in and loosen the soil around the circumference of the bulb until it is loose enough to easily release the bulb when you pull it out by the plant's stem.
Wash the dirt off the canna lily bulb with a hose.
Inspect each of the bulbs. Discard any that are damaged, soft, diseased or significantly smaller than the others. They are likely to develop fungi or other diseases, while in storage, which may spread to healthy bulbs.
Lay the canna bulbs out in a shaded, cool (60 to 70 degrees F), dry place to dry for three days. Turn them at least once daily to make sure they dry evenly on all sides.
Pack the canna bulbs in a plastic or wooden container lined with about an inch of sphagnum peat or vermiculite. Do not allow any of the bulbs to touch. If you must layer the canna bulbs, place a 1 to 2 inch layer of peat or vermiculite between the layers. Cover the top of the bulbs with another layer of peat or vermiculite.
Store the bulbs over the winter in a cool dry place like your garage that remains between 40 and 50 degrees F. Check on the bulbs periodically to make sure none have rotted or developed fungi. Throw any diseased bulbs away.