Canna lilies (Canna spp.) are not true lilies, but a close relative of the banana tree. These tender perennials grow in U.S. Department of Agriculture plant hardiness zones 8 through 12. Cannas grow from rhizomes that send up tightly folded leaves and flower stalks. You can't root the flower stalks to produce a new canna lily, nor can you root the leaves. Propagation is done through division, because seeds do not grow true to the parent plant.
LIfting the Clump
Canna lily rhizomes can be as large as 12 inches long. A good way to lift the rhizome is to locate the edges of the canna clump and use a small spade to loosen the soil around the outer edges. Slide a garden fork under the mass and gently lift it from the flower bed. The rhizomes need wiped off to remove as much soil as possible. You can clean the rhizomes with bleach water that is one cup of bleach to nine cups of water. This helps eliminate any bacteria that may be on the rhizomes.
Dividing the Rhizomes
The canna lily rhizomes grow in sections that may twist and turn. The sections contain eyes, much like a potato, from which the plant grows. You may need to cut back the leaves to see the rhizomes properly. Use a sharp knife to cut the leaves about an inch above the rhizomes. Once the root mass is exposed, simply snap the rhizomes into the number of sections you desire for new plants. For successful propagation and rooting, each section must contain an eye.
Planting Rhizome Pieces
In cool climates, canna lilies are planted after all danger of frost has passed. For warmer or a Mediterranean climate, it's safe to plant Canna lilies at any time. Canna lilies prefer a rich, moist soil and will tolerate slightly more water than many other plants. Choose an area that receives full sun. Mix a generous portion of compost into the soil as a natural fertilizer for the plants. Lay a rhizome section about 3 inches below the soil surface. If possible, have the eyes facing upward, though this is not a necessity. Space the rhizome sections about 24 inches apart to eliminate overcrowding when the plants grow. Cover the rhizomes with a 3 to 4 inch layer of soil and water them to the depth they are planted. Keep the soil slightly moist while the new plants become established.
New Plant Care
Once the new canna lilies start growing, increase the watering schedule. A layer of mulch around the new plants will help the soil retain moisture and provide a weed barrier. Canna lilies send up flower stems in between the leaves. These stems are generally higher than the leaves and don't uncurl. Once a stem flowers and fades, cut that stem down to the next node. Each node will produce another spray of flowers. Deadhead each stem for continuous blooms throughout the growing season. When all the nodes have bloomed, remove the stem and the surrounding leaves to make space for a neighboring canna lily to bloom.
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