Canna

Family: Cannaceae (Canna family)
Genus: Canna

Lily-of-the-valley—Convallaria majalis—is the “official” plant for the month of May. But this year, let’s think larger and bolder. Much larger and much bolder.

Recently I’ve been bitten by the summer-bulb bug, for reasons that aren’t entirely clear, even to me. Perhaps it’s because I want to explore yet another new aspect of gardening. But it’s also a practical way to deal with some bare spots in the garden—particularly in places where I haven’t yet hit on the specific plant I want to install as a permanent resident. Bulbs are easy and quick to put in and practically grow themselves—and here, I’m using the catchall term “bulb” to include rhizomes, corms, tubers, and tuberous roots. So for summer color I can choose from begonias, lilies, and gladiolus—and dahlias, of course. I leave the growing of the latter to Dick Porter. For years I’ve also eschewed lilies and glads. And cannas I wouldn’t even consider. But this year, inexplicably, I’m fascinated with them all—especially canna lilies. Maybe it’s all the times I’ve admired them in Peace Arch Park while waiting in line to cross the border. Or it might be distant memories of old gardens I knew as a child. Didn’t all our grandmothers grow “common” red cannas?

At last count, the genus Canna—the only one in the Cannaceae family—included 55 species indigenous to the tropics and now naturalized around the world. Canna edulis is native to South America, where its fleshy rhizomes are a food source. They’re dried and pulverized into what’s called tous les mois in France and “arrowroot flour” in Britain—although the arrowroot we use here in cooking as a thickener comes from Maranta arundinacea, another plant entirely. The seeds of several canna species are used to make jewelry, because they’re very hard and uniformly shaped. It’s rumored they served as a substitute for lead shot in flintlock muskets during the 18th and 19th centuries.

The canna lily is a perennial grown from a rhizome, just like the lily-of-the valley. The two plants are otherwise unrelated, although the large leaves of the canna do resemble the tiny leaves of the lily-of-the-valley, in form if not in color or size. Linnaeus categorized Canna indica—and he didn’t use leaves so much as the reproductive parts of flowers to organize his classifications. The Canna flower has one stamen and one pistil, which placed it in the Monandria class and the Monogynia order. The word “canna” is from the Latin for “cane” or “reed,” and Linnaeus named that first species he saw after what he thought was its country of origin—India.

What our grandmothers grew might have been Canna indica. It’s actually a New World native and grows in the wild throughout the Caribbean and Pacific islands, where it’s on the verge of being declared a nuisance. It’s unlikely to take hold to that degree in our area. An enormous number of named varieties are now available for our home gardens, and show-stopping they can be. Choose yours carefully. There are cannas with small flowers and others with very large flowers, in a range of brilliant colors. The foliage varies from variety to variety and is frequently as extraordinary as the flowers. You may actually have to depend on the foliage for effect rather than on the flowers, because cannas bloom late in what they hope will be a hot summer. They may be slow to blossom here, in any given year, and may not come into their own until the weather is too cool to sustain them. Where they do get a great deal of heat, some varieties can top out at almost fifteen feet, but you’re unlikely to see that here in our cool-summer climate. Those that are full-size may make it to five feet. If even that’s too much height for the space you have available, select one of the many dwarf varieties. You’ll get the same great flowers and almost as many outstanding foliage choices, but on plants that are only two or three feet high.

Plant your canna rhizomes before the middle of May in the richest, most moisture-retentive soil you can manage, where they’ll get full sun. Place them about four inches deep and eighteen inches apart—eyes up if you can find them, but don’t worry if you can’t. Just lay the rhizomes in the ground horizontally. Cannas are heavy feeders, so add some fertilizer according to package directions when you plant and at monthly intervals during the summer. Use a complete, balanced formulation or—better—one that goes easy on the nitrogen. Avoid feeding cannas excess amounts of this particular nutrient, so make sure that first number is not greater than the other two. All cannas need at least some moisture administered regularly. Read up on your varieties to learn their specific requirements. Some are actually bog plants and will thrive along the shallow edges of ponds. Others are marginal, and appreciate wet feet. Many will do fine with a weekly deep soak.

Watch for slugs when the shoots emerge, and keep checking through the growing season. We know our abundant slug population has quite a taste for things succulent and tropical! Then stand back. When late summer rolls around, you’ll appreciate the “bold” move you took in May.