Canna lilies (Canna x generalis) grow best in full sun and hot weather. They prefer moist soil enriched with lots of organic material. This tender perennial creates dramatic displays in the landscape with tropical foliage and brilliant flower colors. Canna bulbs produce flowers all through the growing season. Since canna plants are tender perennials, they will not survive harsh winter weather if left outside.
Canna lilies grow 1 1/2 to over 5 feet tall, depending on the variety. The plant looks like a banana tree without the thick trunk. The foliage consists of large, glossy green leaves that are 6 to 12 inches wide. Cannas produce 1-foot-tall flower stalks with iris-like blossoms at the top. The flowers form clusters of red, rose, pink, yellow, red with yellow and dark red with bronze blooms.
Cannas are native to tropical and subtropical areas around the world, so they are not cold hardy. The USDA planting zone rates canna lilies for zones 8 to 12. Zone 8 is the coldest zone a canna can survive naturally in with occasional temperatures of 10 to 20 degrees F. In areas like Georgia, Texas, Florida, California, Hawaii and Mexico, canna bulbs do not need any special treatment to survive the winter.
Cannas are commonly grown as annuals in areas with freezing temperatures. They sometimes survive temperatures down to 0 degrees F if they are mulched. Spread 6 to 10 inches of sawdust or straw mulch around the crowns of the canna plants. This will regulate the soil temperature and protect the bulbs underground. If canna bulbs freeze, they may rot in the ground once they thaw out.
Cannas bloom year-round in tropical climates, so storing the bulbs over the winter is just for protection and not a required period of dormancy for flowering. Wait until a frost has damaged the leaves, then cut the canna plants back 3 to 4 inches above the soil line. Dig up the bulbs with a shovel and be careful not to accidentally scrape or cut the bulbs. Remove all the soil from the bulbs. Lay them out to dry for a couple of hours in an area out of direct sunlight. Fill a container like a wooden crate or plastic tub with peat moss. Bury the bulbs so they do not completely dry out over the winter and store in a cool area that stays above freezing.
Replant the canna bulbs outside once the soil has warmed up and there is no danger of spring frosts. Work 2 to 4 inches of compost into the flower bed. If your soil does not drain well, add a layer of sand to the soil. Plant the bulbs 3 to 4 inches deep and 1 1/2 to 3 feet apart. Canna lilies need room to grow since they are large plants.
Canna lilies are used in raised beds and as background plants in the landscape. Their brilliant colors and oversized leaves brighten any corner of your garden. Plant canna bulbs in large containers to create thriving houseplants. Use 1 or 2 canna bulbs in a 3-foot diameter container.