April 07, 2020

Exotic canna a tropical native> Colorful hybrid an elegant addition to our northern gardens

So many plants we grow in our gardens aren’t indigenous to Maine or even to our temperate climate, yet, thanks to technology, we are able to make them thrive. In fact, those of us who enjoy landscaping and flower gardening have come to depend on the visual effects plants of tropical nature can produce in our gardens.

During the Victorian period in America, from about 1860 to the early 1900s, an enthusiasm for cultivating plants native to the tropics became prevalent. The trading of plant material among people throughout the world was so widespread that some plants were used as currency.

For many, the luster of tropical plants was derived from their exotic appearance, richness of texture and lush growth. Today, many of the same aspects create appeal. Technology, including plant breeding, refined methods of plant propagation and techniques in season extension, has made it so that it is easy for us to grow plants that would not grow naturally in our climate.

Here in the north, great landscape effects may be achieved by selecting and growing plants of exotic appearance. One such plant that has resulted from breeding technology — hybridization — is canna. Canna is native to the New World tropics. The botanical name for this exotic-looking plant is Canna x generalis, and many varieties of the plant make a beautiful display in the summer garden.

Ranging in height from 2 feet to 6 feet and available in a wide range of colors, an assortment of canna varieties may be grown from seed or rhizome. Effective in every situation from mass plantings to container gardens, canna hybrids produce either orchidlike or gladioluslike flowers that grow in clusters from about 3 to 6 inches across.

Borne on strong upright stems, red, orange, yellow, white, salmon and pink flowers — some varieties with speckling throughout — are presented atop lush foliage. Simple leaves, 2 feet in length and 6 inches in width, may range in color from green, blue-green, reddish and bronze to purple. Some produce leaves with creamy variegation.

Canna should be grown in full sun. Hardy only to Zone 8, this plant must be grown from seed or rhizome. Grown by rhizome, the specialized stems should be started indoors six to eight weeks before the last expected frost, and should be set out only after the soil is warmed. Once in the garden, cannas require an ample and consistent supply of moisture and can tolerate only occasional bouts of dryness.

For small gardens or a foreground setting, select dwarf varieties such as those in the series Pfitzer Dwarfs. Available in crimson, coral pink and yellow, they will make an eye-catching display. For mid- or background plantings, select a canna that will grow to 3 to 5 feet in height, such as “The President,” “Wyoming,” “Richard Wallace” or “Striped Beauty.”

When frost kills the above-ground foliage of canna in the fall, dig the rhizomes and treat and store them as you would those of gladiolus. Brush away the soil and dip them into a 10 percent bleach solution. Dry the rhizomes for several days, and store them in a well-ventilated box in a cool, dark place for the winter.

Whether grown from seed or rhizome, the old-fashioned flower of canna has a timeless effect in the garden. And although hybridized cannas offer fine visual effects in the garden, one species, Canna edulis or Queensland arrowroot, is valued as the source of arrowroot starch. If you’ve never grown canna, consider selecting from the wide range of hybrids available — you’re certain to find one that fits nicely into your garden plans.

Diana George Chapin is the NEWS garden columnist. Send horticulture questions to Gardening Questions, c/o Maine Weekend, Bangor Daily News, P.O. Box 1329, Bangor 04402-1329. Selected questions will be answered in future columns. Include name, address and telephone number.

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