Known botanically as Canna X generalis, canna lilies are rhizomatous, perennial herbaceous plants that bloom best in warm climates such as those found in U.S. Department of Agriculture plant hardiness zones 8 thorough 11. Gardeners living outside of these zones may also enjoy canna lilies' attractive ovate leaves and showy blossoms by removing the plant's rhizomes from their garden after they've completed their blooming cycle. With the proper care, canna lilies are capable of blooming continuously from midsummer until the first fall frost.
Plant your canna lilies in a full sun location to ensure a long and productive blooming cycle. Canna lilies perform best in sites that receive at least six hours of direct sunlight per day. Plant canna lily rhizomes 3 to 4 inches deep in a prepared garden bed; when planting multiple rhizomes, space them 2 to 3 feet apart.
Irrigate canna lilies weekly while the plants are actively growing and flowering. Provide 1 to 1 1/2 inches of supplemental irrigation each time you water; canna lilies bloom best in moist, well-draining soil.
Fertilize canna lilies in early spring with a water-soluble 5-10-5 fertilizer, applied according to label instructions. Apply subsequent fertilizer applications at the beginning of each month to keep your canna lilies blooming all season long. Cease fertilization just before the first fall frost; resume your regular fertilization schedule the following spring.
Deadhead canna lilies throughout the growing season to keep them blooming for as long as possible. Cut spent blossoms from your canna lilies with sharpened and sterilized garden shears; this stimulates canna lilies to produce another round of blooms.