Canna (aquatic group)

Common Name: canna 
Type: Herbaceous perennial
Family: Cannaceae
Zone: 7 to 10
Height: 2.00 to 6.00 feet
Spread: 2.00 to 3.00 feet
Bloom Time: July to September
Bloom Description: Red, salmon pink, yellow, burnt orange
Sun: Full sun to part shade
Water: Medium to wet
Maintenance: Medium
Suggested Use: Annual, Water Plant, Rain Garden
Flower: Showy
Tolerate: Wet Soil

Culture

Winter hardy to USDA Zones 7-10. In St. Louis, plants are best grown in containers submerged in ponds or water gardens with the crowns under no more than 8” of water. Use organically rich soils in the containers and site plants in full sun to part shade. Lift containers in fall, cut back the plant tops and overwinter the containers in cool, dry, frost-free locations until spring. Longwood cultivars may also be grown terrestrially in consistently moist to wet soils that do not dry out.

Noteworthy Characteristics

Native to South America, Canna glauca is a water canna that is noted for its blue-green foliage and its ability to grow well in shallow water. Species plants grow 4-6’ tall and feature narrow, blue-green leaves (to 18” long) and small pale yellow flowers. In the 1970s, Longwood Gardens in Kennett Square, Pennsylvania crossed Canna glauca with several different terrestrial cannas. The result was the Longwood cultivars, which are four hybrid water cannas that typically grow 2-6’ tall with a spread of 2-3’ as follows: (1) ‘Endeavor’ (red flowers), (2) ‘Erubus’ (salmon pink flowers), (3) ‘Ra’ (yellow flowers) and (4) ‘Tanny’ (burnt orange flowers). Longwood cannas typically bloom all summer.

Genus name comes from the Greek word kanna meaning a reed.

Problems

No serious insect or disease problems. Japanese beetles, caterpillars, slugs and snails may chew on the foliage. Watch for aster yellows.

Garden Uses

Accent or mass in pond or water garden margins. Large containers. Backgrounds or borders as long as moist soil requirements can be met.