Canna As Foundation Planting

Size and Space

• Canna lilies are tropical bulb perennials that grow up to 3 to 8 feet in height and to 3 feet in spread. These plants require generous spacing in the landscape, and may fail if their growing location becomes crowded and competitive. Plant cannas in spots that provide good air circulation and plenty of room. Divide canna lily bulbs every three to four years to propagate new plants and keep sites from becoming crowded.

Cold Hardiness

• Cannas are not hardy bulbs, and fail in the frozen winters of U.S. Department of Agriculture growing zones 8 and below. While gardeners in zones 9, 10 and 11 can leave canna bulbs in the ground year-round, gardeners in zone 8 and below must dig canna bulbs in fall and replant them in a box of topsoil for winter storage and protection. For this reason, cannas should not be considered for winter landscaping.

Location

• Cannas are tropical plants, and do best with full sunshine for six to eight hours a day. Plant them only in sites where they receive full sun and quick drainage. As foundation plants, cannas should only grow in open areas, as they will not thrive under trees or taller plants.

Ongoing Care

• As perennials, cannas bloom, then yellow and die down to the ground in preparation for winter dormancy. Plant the bulbs in a loose, nutritious mixture of garden soil and organic compost for healthy growth, and water them with 1 to 2 inches of water every three to four days to maintain good soil moisture. Cannas that don't have enough nutrition or water may not have the resources for blooming. When cannas begin to yellow, allow the foliage to die on its own; the leaves gather nutrition for future blooms at this time, so cutting off yellow foliage damages the bulb's store of nutrition.