Gardening: Hardy Clematis That Thrive on the Prairies

How do you know if the plant you are considering is hardy or needs shelter?

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Clematis (from the Greek word for vine) are among our most beautiful vines. While many do very well on the Prairies with average care, others, such as the Jackmanii, require plenty of pampering, coupled with your most protected microclimate. Even then, they may not survive our winters.

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All Clematis share the same amount of space on benches in garden centers and nurseries. So how do you know if the plant you’re considering is hardy or needs shelter? Start with the Latin or botanical name – which should always be italicized on the plant label.

The hybrids of Clematis alpina and Clematis macropetala (both native to China) are among the most beautiful and tough. They range in height from about 2.6 to four meters and climb by twin petioles, so leave room behind their supports for the leaves to do their job. Both varieties bloom on the previous year’s growth from late spring to early summer. The hybrid varieties of both species require little pruning unless blocking a window or arbor, usually every three or four years. They benefit from being planted in deep, organically enriched soil with a 10cm layer of organic mulch at the base, and water deeply every two weeks (to a depth of 45cm). Flowering is greater if the vine is in sunlight. These clematis are hardy, easy to grow and vigorous. No hassle, no hassle.

The alpine clematis (Clematis alpina), native to the Alpine slopes of Europe and Asia, was introduced to England in 1792. It has bell-shaped flowers in shades of white, pink, or blue. The compound leaves consist of three groups of three leaflets and coil around the support as it grows. They generally reach a height of two to 2.5 m. Among the cultivars are ‘Ruby’ with deep pink-dusty rose-red flowers; ‘Willy’ with pale mauve-pink flowers with a darker edge; ‘Constance’ with bright pink, almost red flowers; ‘Francis Rivis’ with larger deep blue flowers; ‘Pamela Jackman’ with rich, deep purple-blue flowers; and ‘Helsingborg’ with deep purple flowers.

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The large-leaved clematis (Clematis macropetela) was first discovered in China by a French missionary, Pierre Nicholas Le Chéron D’Incarville, in 1742. But it was not introduced to Europe until just before World War I. It is slightly larger, usually between 3.6 and four meters, with bell-shaped flowers. Many of its varieties were developed by Prairie breeders such as Frank Skinner and Stan Zubrowski. Among Skinner’s introductions are ‘Blue Bird’ with deep lavender-blue flowers, ‘Rosy O’Grady’ with long dark pink pointed sepals, and the snow-white ‘White Swan’. ‘Joe Zary’, in honor of one of Saskatoon’s promoters of horticulture, has double purple flowers and was introduced by Stan Zubrowski of Prairie River. Other Clematis macropetala varieties include ‘Lagoon’ and ‘Maidwell Hall’ with blue flowers and ‘Markham’s Pink’ with pink flowers. A Scandinavian introduction, ‘Jan Lindmark’ has dark blue-pink flowers, while ‘Purple Spider’ has double purple flowers.

'White Swan' was crossed by Frank Skinner.
‘White Swan’ was crossed by Frank Skinner. Photo by Brian BaldwinIncluded photo

Very different from all of the above are the hybrids of the herbaceous Clematis integrifolia and the climbing Clematis jackmanii. These begin growing at ground level each spring and grow to about a foot or two on the current season’s growth rate in late summer. Although the roots survive, the above-ground part is killed to ground level each winter and should be pruned in early spring. One of the best known of these is ‘Blue Boy’, introduced by Frank Skinner in 1947. Beautiful blue, it blooms in late summer. A more recent introduction from Crimea, Ukraine is ‘Pamiat Serdta’ with light purple flowers.

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Note: Golden clematis (Clematis tangutica) is on Alberta’s list of noxious weeds and is discouraged by the Native Plant Society of Saskatchewan for its vigor and abundant self-seeding.

Sara’s most recent book, retired from the University of Saskatchewan, is Growing Fruit in Northern Gardens with Bob Bors. She has been organizing garden trips for over 20 years – to Great Britain, Ireland, Europe, Turkey and Iceland. Join her on a tour of the French Gardens in September [Contact Ruth at 1-888-778-2378, worldwideecotours.com]

This column was made available by the Saskatchewan Perennial Society. Reach the association by email at saskperennial@hotmail.com or visit their website at saskperennial.ca. You can find them on Facebook at facebook.com/saskperennial.

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