How to Care for a 'Tropicanna' Canna
Lush, tropical foliage, vibrant flowers and low care requirements makes Tropicanna canna (Canna indica 'Phasion'), a true workhorse in the garden. This canna variety is striking with its variegated foliage which sports yellow, red, pink and green stripes on a maroon background. The flowers, which bloom from summer through fall, are bright orange. Tropicanna canna grows in U.S. Department of Agriculture plant hardiness zones 7 thorough 11. In frost-prone climates, the stalks, leaves and flowers die back to the ground in winter.
Feeding and Watering
Water Tropicanna canna plants each time the soil dries out 3 inches deep. Soak the area slowly until the area feels moist 6 to 12 inches deep.
In spring, when new shoots start to emerge, fertilize with slow-release 10-10-10 fertilizer. Use 1/2 tablespoon per plant. For large beds, use 1 cup per 30 square feet, sprinkled evenly over the soil. Water after spreading the fertilizer until the soil is damp 6 inches deep.
To avoid overwatering, time the annual spring fertilizing to coincide with a regular watering.
Trimming and Pruning
In frost-prone climates, cut back all the stalks after the first frost damages the leaves. Use a pair of pruning shears to cut the fleshy stalks level with the soil. Look for new shoots in spring. In frost-free climates, cut down stalks as they start to dry up and die back.
Cut the flowering stalks -- being careful not to damage new shoots of growing leaf stalks -- at the soil level after the flowers fade. Or, leave the flowers to die and drop naturally. Eventually the leaf stalk will die back.
Keep diseases from spreading in the garden by practicing good sanitation. After cutting back Tropicanna cannas, soak the blades of pruning tools in undiluted household disinfectant, such as Lysol, then rinse and dry before storing.
Check Tropicanna for slugs, snails and caterpillars, picking them off by hand as you find them. Crush the pests under a garden boot, or drop them in a bucket of water with a capful of dish soap to drown them. Japanese beetles eat canna leaves. These 1/2-inch-long beetles have a metallic green look to their wings. Inspect cannas weekly or more often. The most effective, least toxic way to eliminate these pests is by handpicking them as you find them. Crush the beetles or drown them in a bucket of soapy water.
Diseases and Troubleshooting
If you notice canna leaves starting to turn yellow, exposing prominent green veins, it indicates a viral infection called aster yellows. Dig up and discard the affected cannas to keep the disease from spreading. Recovery is unlikely.
Overwintering Canna Bulbs
In USDA zones 6 and lower, cut back Tropicanna canna stalks in late fall leaving 4 inches of stalk before the first hard freeze. Dig up the rhizomes and store them in dry sawdust or peat moss through the winter. Keep the bulbs at around 40 degrees Fahrenheit until spring. After the last expected frost, replant the bulbs in the garden 4 to 6 inches deep in a sunny spot.