Cannas
Many gardeners have strong opinions about cannas. Some adore their bold presence and minimal maintenance, while others find them too big or flat-out gaudy. The way I see it, you’ve got to like, if not respect, a statuesque plant that doesn’t require staking. Plus there’s the wide variety of foliage and flowers available in cannas, which are popularly called canna “lilies”. Hands down, my favorite canna—and probably the best-known variegated variety—is ‘Bengal Tiger’. Four to 6 feet tall, it has large, bright-green leaves with yellow pinstripes and a narrow purplish edge. The orange flowers are akin to gladiolus, opening in succession from the bottom of the stalk up. ‘Bengal Tiger’ plays surprisingly well with others—complementing a wide range of color and textures in other perennials. The foliage is a nice backdrop for my lavender-flowered bee balm, which brings out the purple outline of the leaf. It also looks dashing with red hot pokers (Kniphofia uvaria). If you like the foliage but the flowers clash with your color scheme, just remove the flower stalks as they appear. ‘Tropicanna’ is another eye-popping canna that has purple and red striped leaves and large bright-orange flowers. For its nice green-and-white variegation, ‘Stuttgart’ is another stunner. Unlike most cannas, which perform best in full fun, this one needs some shade to prevent leaf scorch. Some cannas have bi-color and speckled blossoms. If you’re adventurous, ‘Cleopatra’ is an unpredictable charmer—its flowers are red, yellow, red-and-yellow or yellow with red spots, and its foliage may be green, burgundy or a combination.
Though varieties with red, yellow and orange flowers abound, not all cannas are overstated. Some have flowers of peach, pale pink and buttery yellow. Shorter varieties are also available (18 inches and up). Depending on variety, the flowers of various cannas may be shaped like gladiolus, iris or orchids.
Though cannas are easy to grow, they are susceptible to some pests and diseases. Canna leaf rollers are caterpillars that feed on leaves. The best way to prevent infestation is to remove and destroy the dead foliage after frost, which will eliminate the pupae that overwinter in the leaves. Infested plants may be treated with selective pesticides that target leaf-chewing caterpillars. An organic option is Bt (Bacillus thuringiensis), available in powder or liquid form under various trade names. Pesticides should be applied to both the upper and lower surfaces of the leaves. A host of viruses may cause distorted growth and crinkling, streaking or mottling of leaves. No treatment exists for viruses. Sick plants should be dug up and destroyed. It’s a good idea to pot up rhizomes you’ve purchased or begged before setting out the plants so you can check for disease.