Cannas add tropical flair to the garden

The trend toward dramatic tropical gardening continues, with canna lilies moving steadily forward from background to center stage. "Hybridizers are seeking new colors, as pinks, magentas and pastels, and new forms, such as the Longwood Water Cannas bred for growing in water," says James W. Waddick, co-author, with Glenn M. Stokes, of a forthcoming book, "Cannas You Can Grow." "Other new trends are dwarf cannas, variegated foliage, and more self-cleaning [flowers that automatically fall off when faded]."

Dr. Waddick specifically mentions the potential of Tropicana with its "hot red and purple, jungle colors in the foliage," and the midsize Liberty Cantaloupe, which produces lots of cantaloupe-colored flowers.

But the choice in garden catalogs and in some nurseries is almost endless. There seems to be a canna for every garden requirement.

The broad reddish-purple leaves of 4-foot high Durban are dramatically yellow striped, which set off, rather than clash with, the large scarlet flowers.

If you need something almost 7 feet high - and really want an eye-popper - Phaison [photo above right] might fit the bill. Purple, yellow, and red stripes create leaves of flame around bright orange flower torches.

A bit much? Never fear. The huge, almost-triangular leaves of 7-foot-high Stuttgart are grass green with large white stripes. And the small peach-colored flowers that appear in late summer are equally serene.

You don't have all that garden space? "I like the dwarf varieties for smaller-scale use," says Pam Peirce, author of "Golden Gate Gardening."

"These include pinks, like Liberty Pink and Pink Futurity - both with burgundy leaves - as well as Salmon Pink. These colors extend the usefulness of cannas in garden color schemes."

Other smaller cannas include:

* Cupid, which stands about 2 feet, and has pearl-pink and lavender blossoms.

* Striped Beauty, which grows between 2 and 3 feet high. Its buds are red, and its yellow-and-white-striped flowers are cradled in green-and-yellow-striped leaves.

* Yellow Leopard, which has lemon-yellow flowers dotted with maroon. Growing to about 18 inches high, it's part of a "new race of groundcover cannas," according to Waddick.

Whether planted in a pond, in the ground, or in a large container, cannas are sturdy plants, if given ample sun and lots of warmth.

Some cannas may be grown without full sunlight. Pretoria - especially trendy in the North, with its gold-and-green striped leaves - tolerates some shade, as do Stuttgart and Intrigue.

Cannas are usually best displayed in groups of a single type, perhaps spotlighted against a quiet background, such as a fence or evergreen shrubs.

Easy-care cannas

Care is minimal. Water well at least once a week, depending on the weather, when the plant is in flower. Fertilize regularly, with a brand mentioning flowering tropical plants. For best appearance, pick off faded blossoms. After the entire flower cluster has bloomed, cut the stalk close to the ground.

If plants become crowded, divide the rhizomatous rootstock in the spring and replant, giving extras to friends or neighbors. There should be at least one prominent "eye," and preferably several, on each divided piece.

For the truly dedicated, some of the dwarf cannas, such as Tropical Rose, may be grown from seed.

This is a fun and usually successful undertaking because of the large seeds. Soak seeds overnight to hasten germination, which usually occurs within two weeks. Flowering may occur the first year. Canna seed isn't the easiest thing to find, however. Check garden catalogs for availability

If your desire to acquire cannas is quelled by a fear that they won't fit in your climate zone, rest easy. "Cannas can be grown in Anchorage if the summer is warm, and they're grown in containers," says Julie Riley, an Alaska extension horticulture agent who has grown cannas in containers on her kitchen table. "Just place them in a 'hot spot,' - i.e., no wind, [but with] reflected light and heat."

"Virtually no part of the United States is too cold for cannas during the summer," emphasizes Mr. Stokes.

Where temperatures never fall below freezing, they may flower throughout the year. In zones where the temperature doesn't drop below 20 degrees F. in winter, cannas bloom during the warmer months and often into fall. When cold weather hits, cut off the fading stalks. The rhizome stays snug underground, waiting to send up new growth when spring arrives.

If you live where temperatures drop below 0 degrees F., cannas in the ground should be lifted and stored during winter. Dig them up after the first cold spell, cutting off all leaves and stalks above the 6-inch mark. Store at about 50 degrees F. in "[slightly moist] peat moss - not damp, not dry," says Stokes.

"Cultivars such as Bangkok have very skinny rhizomes and can be difficult to store" because they easily dry out, mentions Waddick. "Others, like Omega, can almost sit on a shelf all winter and still be fine. Cultivars with large rhizomes store easiest."

Replant in late spring, after the soil has warmed up. For earlier blooms, start the rhizomes indoors about four weeks before the date of the last frost.

One rhizome per half-gallon milk carton containing a mixture of peat moss and loam gets good results. Plant rhizomes outdoors about 4 inches deep and 18 to 36 inches apart, depending on the plant's mature size.

The versatile canna that gardeners enjoy today hardly resembles the cannas of yesteryear. In the 1800s, adventurous botanical collectors traveled worlds quite unknown to Europeans, seeking new plants.

Grown by headhunters

One was a 23-year-old from Scotland, George Don. In 1822, he set sail on the H.M.S. Iphigiea for the coast of Africa. "The Golden Age of Plant Hunters," describes some of Don's exciting finds: "... here, against a backcloth of red ochre earth and dense greenery of mountain slopes, was a picture of foliar color and form so different, so unusual, as to seem incredible.... Large yellow cactus flowers filled the hedges, while the brilliantly hued cannas at their feet shouted their sanguinary message."

More than a century later, noted botanist Wendell H. Camp told of his trek through the Ecuadorian Andes searching for new plant varieties. "Only one real obstacle lay ahead," he wrote in "The World in Your Garden." The obstacle was the Jivaro Indians - former headhunters, he hoped. But worries were quite unfounded. Visiting the tribal chief, he got a peaceful garden tour. Among the many plants was a species of canna, which the Jivaros grew for food, utilizing the starchy, tuberous rhizomes.

The North American nickname for canna is Indian Shot, because the hard, round, shiny seeds somewhat resemble the lead shot ammunition used in 18th- and 19th-century flintlock guns.

South American Indians formerly collected the the seeds, placed them in nutshelss, and used them as rattles.

In today's gardens, butterflies, hummingbirds, moths, and bees enjoy visiting canna lilies.

Plants that go well with cannas include bronze fennel, marigolds, ornamental grasses, salvia, verbena, and zinnias. Bulbs that do well in the same area include Crocosmia, elephant's ear, foxtail lilies, lilies, and Liatris.

Container options can include color harmonies, says Waddick. "Yellow marigolds with yellow cannas, red zinnias with red cannas, or something that will trail around the base of smaller cannas, like trailing nasturtiums. The container should incorporate small, medium, and tall plants to create a very full look."

(c) Copyright 2001. The Christian Science Monitor