There's nothing timid about cannas. Native to the southeastern region of the U.S. as well as to subtropical and tropical parts of Central and South America, they loudly proclaim their presence with large, bold leaves and wildly colorful flowers.
In summer and fall, flower stalks (typically 36 ft. tall) bear blossoms to 3 in. across, in shades of red, orange, yellow, salmon, coral, pink, and cream; both solids and bicolors are available. Lance-shaped, 1- to 4-ft.-long leaves resemble banana foliage. Green and bronze are the typical leaf colors, but many newer selections feature shockingly bright striped and variegated foliage in all sorts of riotous combinations. Deep-colored foliage typically fades somewhat in hot sun.
Cannas are most effective when planted as masses of a single color against a solid background. They grow best with full sun and high heat, forming lush, spreading colonies. Their leaves combine well with finer-textured foliage, such as that of daylilies (Hemerocallis) and lantana. Use taller kinds at the back of borders; compact sorts make good container plants.
C. flaccida. SWAMP CANNA, SOUTHERN MARSH CANNA. Native to swamps and riverbanks from South Carolina to Florida. Grows 4 ft. tall, 3 ft. wide, with green leaves reaching 2 ft. long and 6 in. wide. Bright yellow, 3-in.-wide flowers.
C. hybrids. The vast majority of cannas grown are hybrids grouped under Canna x generalis. They feature larger flowers than their parent species and often have strikingly ornate foliage. Most are good subjects for the back of the border. Give them plenty of room, as nearly all spread quickly. Recommended selections include the following.
'Australia'. To 45 ft. tall. Glossy, burgundy-black foliage holds color in summer heat. Bright red flowers.
'Black Knight'. To 56 ft. tall, with blackish bronze foliage and velvety deep red flowers.
'City of Portland'. To 4 ft. tall. Vigorous, bushy plant. Broad green leaves; showy rosy pink-to-salmon flowers.
'Cleopatra'. To 4 ft. tall. Green leaves and stalks are marked with large purple blotches. Flowers arising from purple tissue are red; those coming from green tissue are yellow. The bicolored foliage tends to revert to plain green; cut out solid green stalks to prevent reversion.
'Constitution'. Grows 5 ft. tall. Narrow, grayish purple leaves with burgundy edges; pale coral-pink flowers. Slower spreader than most cannas.
'Durban'. To 4 ft. tall. Strikingly variegated foliage features yellow veins against a reddish purple background. Large scarlet flowers. Slow spreader.
'Ehemanii' (C. x ehemanii). Old-fashioned favorite grows 68 ft. tall, with rich green leaves and pendulous flowers in deep rose-pink. Good for back of border.
'Erebus'. Compact grower to 34 ft., bred for use in water gardens. Gray-green leaves and salmon-pink flowers.
'Ermine'. To 3 ft. tall. Large, creamy white flowers with a pale yellow center. Gray-green foliage.
'Intrigue'. To 78 ft. tall. Narrow, erect, deep burgundy leaves are topped with many small, light salmon blooms.
'Minerva'. To 5 ft. tall. Leaves are striped green and white; large yellow flowers open from red buds.
'Phaison' ('Tropicanna'). To 6 ft. The most shockingly gaudy foliage imaginablepurple leaves striped with yellow and red. Backlit leaves glow as if ablaze; bright orange flowers complete the fiery picture. Very susceptible to canna leaf roller. Feed frequently to keep foliage looking its best.
'President'. To 4 ft. Masses of large scarlet blooms top glossy green foliage.
'Pretoria' ('Bengal Tiger', 'Striata'). To 6 ft. tall. Dramatic-looking foliage features green and yellow stripes and maroon edges; glows brilliantly when backlit. Bright orange flowers.
'Red King Humbert' ('Roi Humbert'). To 4 ft. Reddish bronze foliage; large orange-scarlet to red flowers.
'Tropicanna Gold'. To 45 ft. Orange-yellow flowers speckled with dark orange. Leaves striped in green and gold.
'Wyoming'. To 4 ft. Bronzy purple foliage and bright orange blooms.
'Yellow Humbert'. To 5 ft. Green leaves; large bright yellow flowers splashed with spots of crimson.
Low-growing hybrids. Standard-size cannas take up a lot of roombut fortunately, you can find many low-growing hybrids that are better suited to containers and small gardens. 'Striped Beauty' ('Bangkok Yellow'), to 23 ft. tall, has striped foliage and flowers; leaves are striped in green and white, and red-throated yellow flowers are marked with white stripes. 'Pink Sunburst', to 3 ft. tall, has green- and white-striped leaves with a reddish cast; its large flowers are salmon-pink. Cannas in the Futurity series grow 23 ft. tall and come in orange, pink, red, rose (all with burgundy foliage), and yellow (with green leaves). Pfitzer's series are green-leafed plants 2212 ft. tall, with coral, crimson, primrose yellow, or salmon-pink flowers. Tropical series plants grow 212 ft. tall, have green leaves and rose, red, salmon, or white flowers. They're easy to grow from seed, blooming 90 days after sowing. The shortest of all cannas to just 112 ft. highbelong to the Seven Dwarfs series; they have green leaves and sport flowers in the full range of typical canna colors.
C. indica. INDIAN SHOT. Native to the tropical Americas; naturalized in the Southeast. To 4 ft. tall, 112 ft. wide. Green leaves 112 ft. long, 8 in. wide. Bright red, tubular, 3-in. flowers. The hard, round seeds were used as shot by early colonists.
C. musifolia. BANANA CANNA. Grows 12 ft. tall. Huge canna that resembles a banana tree. Large green leavesto 2 ft. long and half as widehave burgundy-red margins and stalks. Small red flowers are sparsely produced. Great as a tropical-looking accent.
C. warscewiczii. Native to Mexico. To 6 ft. tall, 3 ft. wide. Big burgundy leaves, 2 ft. long and 1 ft. wide, on very dark stems. Small, tubular red flowers, attractive to hummingbirds, are carried in spikes held high above the foliage; spent blossoms drop cleanly from the spike. Not susceptible to canna leaf roller.
Choose a spot with plenty of heat and bright sunshine. Plant rhizomes in spring, after the danger of frost is past. Set them 24 in. deep and 12 ft. apart. Cannas like lots of moisture (they'll even grow in standing water), but the soil doesn't need to be boggy, just moist. They're heavy feeders and prefer rich soil containing lots of organic matter, such as composted manure and chopped leaves. If you see ragged, stunted foliage and canna leaf roller (see below) is not the problem, the plants are hungry; give them weekly feedings of water-soluble 20-20-20 fertilizer until they perk up. Cut each flower stalk to the ground after it finishes blooming; new stalks will appear and continue to grow into early fall. In the Lower, Coastal, and Tropical South, cannas can overwinter in the ground; elsewhere, lift the rhizomes in fall and store over winter. Divide clumps every 3 or 4 years, making sure each piece of rhizome includes a bud or eye.
Canna leaf roller is a common pest, mainly attacking hybrids. This caterpillar rolls up the leaves and feeds inside them; infested foliage looks ragged and is full of holes. Sanitation is the best solution. Cut off and destroy infested leaves as soon as you notice them and, in late fall, cut all plants to the ground and destroy all leaves and stems to prevent the pest from overwintering.
Unfortunately, an incurable viral disease has spread rapidly in recent years to infect many cannas worldwide. Plants are not killed outright, but their leaves are seriously disfigured by brown edges and dead areas. Early signs include yellow streaks and tiny, sandlike spots; flowers may also show viral streaking. Immediately dig and destroy infected plants. Buy replacement rhizomes only from sources you trust to have disease-free stock. Or buy plants in leaf, making sure there are no signs of virus on your chosen cannaor any others in the nursery.