Cannas add tropical garden color, tolerate Texas summers

Gardening in North Texas means we deal with the challenges of hot weather and limited water resources. But we still love to have a bit of the tropics in our gardens, and that's where canna lily plants come in. These heat-hardy beauties will add a splash of color to any landscape.

The basics of cannas

Cannas grow from a thick rhizome that stays very close to the surface of the soil. The stalks rise to between 3 and 8 feet tall, depending on the variety. Each thick stalk has six to eight lance-shaped leaves about 2 feet long. Most leaves are emerald green, but they can also vary in hue from deep green through reddish green, making a bold statement in any garden.

The flowers of the canna appear in summer on short spikes of four to six florets, each with 3- to 4-inch-long petals. They are largely scentless and come in a wide range of colors -- red, orange, pink, yellow, cream, and any combination of these. You won't find any that are blue, purple or true white.

Cannas are native to the tropics of North and South America where they generally grow in shady locations. However, here in Texas, they do quite well with morning sun. Cannas can provide a colorful tropical backdrop to your garden all summer and well into fall.

Most experts recommend growing cannas in heavily amended rich soil to imitate their native habitat. But my cannas have been growing in heavy clay in an east-facing garden bed for perhaps a decade and come back strong year after year. A yearly mulching of my canna bed is really all it needs. If you find your cannas are not blooming, add one or two applications of fertilizer to your yearly care.

Caring for cannas

Cannas will grow best with regular watering but they are also tolerant of dry conditions. I confess to being somewhat of an erratic waterer. Fortunately, cannas grow thickly enough to shade their roots and tolerate dry periods even throughout the heat of summer.

Although canna stalks are quite thick (about 2 inches in diameter), they can be easily cut with hand pruners. During the summer, cannas will produce flowers several times if you clip the spent flower stalks. Clip them down to 2 or 3 feet tall to encourage new growth.

Cannas can be grown in containers but the pots need to be large, at least 2 feet in diameter and at least as deep. Anything smaller just wouldn't have enough soil mass to support the roots and tubers for such a tall flowering plant. Pot-grown cannas should be lifted and repotted with new soil every year to keep them healthy.

The one negative about growing cannas is their response to freezing temperatures. Any above-ground foliage and stems blacken and die when a freeze hits. The underground rhizomes, however, are just fine and will overwinter nicely in Texas. When a freeze hits, cut all the frost-damaged stalks down to the ground with a sharp knife. With the soil uncovered, this is a good time to spread a layer of mulch in preparation for the coming spring.

Pests and problems you may see

Smaller sucking insects such as spider mites and aphids are rarely seen on cannas. You are more likely to have damage from slugs and snails that love the dark moist areas around the base of cannas and climb at night to snack on the leaves. If you notice a series of 1-inch holes in a leaf, it's probably the work of a slug or snail. Snail bait spread around the base of the cannas should take care of this.

Should your canna leaves fail to unfurl, take a closer look and you will probably discover fine webbing holding the leaves together. This is the activity of canna leaf roller caterpillars, immature forms of the brown skipper butterfly living in the furled leaf. Because this pest can produce several generations in a growing year, it's best to clip off the sections with the rolled leaves and discard.

Cannas in your garden

The tall-growing canna plants should be placed in the back of your flower beds, where they can reach their height and be ready to bloom during the summer. Their dramatic tropical foliage will serve as a backdrop for other plants.

Canna rhizomes grow horizontally and will slowly spread to neighboring garden areas. To keep them in check and revitalize the bed, dig up the rhizomes every two to three years during late winter. With a sharp knife, remove any dead or spent sections of the rhizomes. Divide each section so they have at least three reddish growth buds on the top. Replant a few inches below the soil and about 2 feet apart, giving them room to spread.

Varieties to look for

There are dozens of canna varieties, each with a unique combination of leaf and flower colors. Here are just a few of the cannas you can find:

Cannova 'Bronze Scarlet' sports showy scarlet flowers on top of deep-bronze foliage. It grows to about 4 feet tall.

'The President' offers deep red blooms, and the stems grow about 4 feet tall with dark green leaves.

'Yellow King Humbert' has been a garden favorite for over a century. The buttery yellow flowers are splashed with orange. Stalks grow 4 to 5 feet tall.

'Tropicanna' is topped with bright orange flowers and has burgundy leaves that develop fine stripes of red, pink, yellow and green as they mature. It grows to 6 feet tall after the second year.

'Cleopatra' is a spectacular beauty. Flowers on the same plant vary from all-scarlet to yellow with scarlet stripes to dappled scarlet on yellow. Leaves are variegated bronze on 4-foot-tall stalks. This variety can be hard to find some years but worth the effort.

Ann McCormick is a Fort Worth freelance writer.