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Dazzling Dahlias
by Liesbeth Leatherbarrow
by Liesbeth Leatherbarrow

Liesbeth has written for several western gardening publications, including Gardens West and The Gardener for the Prairies. She has also co-authored three gardening books: The Calgary Gardener (with the Calgary Horticultural Society), The Calgary Gardener, Volume Two: Beyond the Basics (with Lesley Reynolds), and 101 Best Plants for the Prairies (with Lesley Reynolds).

June 10, 2007

Dahlias were first discovered in Mexican gardens by Spanish explorers who, enamoured with their novelty and beauty, sent them back to their homeland. Originally named cocoxochitl in their native Mexico, these plants did not take Europe by storm as expected. However, the Spanish loved them, and in 1789 the Spanish king renamed the lovely plants dahlias, after Professor Anders Dahl (1751-1789), a Swedish botanist responsible for developing many new varieties. He also proclaimed that any other country possessing this flower did so illegally because its country of origin, Mexico, was a province of Spain. Until recently, dahlias were also called georginas, after Johann Georgi of Petersburg. The name georgina is still used in Eastern Europe today.

Although dahlias were slow to catch on in Europe for their ornamenatal value, many people thought that the fleshy tubers, which were high in fructose and thus very nutritious, would be an admirable food source and substitute for potatoes. After all, they had been eaten in Mexico, and South and Central America for centuries. The only problem was their terrible taste. According to one Victorian, dahlias have a "repulsive, nauseous, peppery taste [which] inspires equal disgust in man and beast."

Because of their high sugar content, dahlia tuber were sometimes used medicinally. In fact, before insulin was discovered, diabetics were given injections of "diabetic sugar" made from dahlia tubers.

Dahlias, with their staggering diversity in size, shape, and colour, are a plant collector's dream. From the short, compact, bushy bedding dahlias, to the tall, large-flowered favourites with blossoms the size of dinner plates, dahlias are flamboyant and colourful from mid-summer to first frost.

No matter what their size, all dahlias produce stiff, upright stems and divided green or purplish leaves in abundance. Blossoms can range in size from a few centimeters to over 25 centimeters, and come in almost every colour except true blue. The variety in flower forms is astonishing; globe-shaped ball and pom-pom types, spiky cactus-flowered types, daisylike singles, puffy centered anemone types, and elegant peonylike flowers are all available at garden centers or through specialty catalogues.

Dahlias grow from tuberous roots; plant them in full sun, in average to fertile, well-drained soil, after the last expected spring frost, and make sure the growth points are at least 10 centimeters below the soil surface. An organic mulch helps to conserve soil moisture and regular deadheading prolongs the period of bloom. Dahlias are heavy feeders, so they also benefit from supplemental feeding.

Because dahlia tubers are not hardy here, many gardeners grow them as annuals and replace the tubers every year. Others lift, dry, and store them in a cool dry place until spring. Before replanting them, divide the tubers, making sure that each section has some stem attached.


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