Cannas are exotic, tropical plants valued for their attractive foliage and showy flowers that appear in shades of white, yellow, orange, red and pink, depending on the variety. Cannas grow from bulb-like structures known as rhizomes that may require special care during the winter months. Native to warm areas of South America, canna bulbs cannot tolerate freezing temperatures and are winter hardy in zones 9 through 11 only. Gardeners in all other zones must dig and store the rhizomes through the winter and re-plant outdoors the following spring.
Plant canna bulbs after all danger of frost has passed in a location that receives full, direct sunlight throughout the day and consists of moist, well-drained soil for optimal growth. Space canna bulbs at least 1 to 2 feet apart to allow room for growth.
Water canna rhizomes once every 14 days, except during periods of drought when water should be applied once every seven days. Do not allow standing water to build up around the plant, as crown rot may occur.
Feed canna bulbs twice per year, once during late spring and again during midsummer. Use a 10-10-10 NPK fertilizer to provide adequate nutrition for foliage, flower and root production. Apply at the rate recommended by the manufacturer for the best results.
Remove faded or spent canna flowers whenever possible to prolong the blooming season and encourage the formation of additional flowers. Snip off the flowers at their point of origin to reduce damage.
Cut canna plants to a height of 4 to 6 inches immediately after the first hard frost of winter. Use a spade to dig up the rhizomes, and allow them to dry at room temperature for three to four hours. Store in a mesh bag at 40 to 50 degrees Fahrenheit until time to replant in spring.