Plants for the Cold

By David Tarrant | Image: John Glover/DavidTarrant/Al Dodson/Bob Gibbons/Rosie Mayer/Patricia Habidgell

Those of us in the mild southwestern corner of B.C. often forget about the challenges faced by our fellow gardeners in the colder parts of our province. Over the years I have had the pleasure of seeing gardens in some quite remote and beautiful areas, such as the town of Atlin in its magnificent setting on the lake surrounded by spectacular mountains. Another lovely spot is the community of Dawson Creek, way up in the Peace region close to the Alberta border, with its heritage gardens that welcome summer tourists as they make their way to the Alaska Highway.

There are many attractive plants hardy to such areas, and this seems like a good time of year to highlight some as you sit in the cozy warmth of your home, dreaming about next season's garden.

Acer tataricum ssp. ginnala, more commonly known as Amur maple, is a very nice-looking small tree or shrub native to northern China and Mongolia, making it hardy to zone 2. This delightful shrub can be up to 5 m (16 ft.) tall. Its leaves are opposite and about 7 to 10 cm (2.8 to 4 in.) in length. An elongated central lobe and two smaller ones on each side give them a maple shape. The veins on the undersides of the leaves and the petioles are deep red, adding further interest to the plant. In spring the stems bear tiny panicles of scented yellowish-white flowers.

In fall the foliage turns a glowing orange red. But buyer beware - the colour varies from specimen to specimen according to Sara Williams and Hugh Skinner (authors of Best Trees and Shrubs for the Prairies, published by Fifth House in 2004). It's best to purchase these trees in fall as container plants, when their true colours are showing.

I prefer them left as multi-stemmed specimens, which I think gives them a bold presence in your garden. A grouping of three would be even more impressive in fall. However, some people like to keep them pruned to a single trunk, reminiscent of Japanese maples, which are only hardy in the south. I once saw one pruned in such a manner, with its trunk slightly angled out over a small pond next to a stone lantern. The whole scene was quite exquisite and brought a touch of Japan to a northern garden.

Aesculus glabra, or Ohio buckeye, is another good choice. It is, in fact, native to central and eastern zones of the US and is hardy to zone 3 and up. This delightful tree grows to 15 m (50 ft.) in height and is under-used in colder gardens. The form of the tree is broadly conical - somewhat like the outline of a tree one drew as a child. The foliage is typical of a horse chestnut, palmate with five leaflets, each ovate, pointed and up to 15 cm (6 in.) in length. In fall they turn a beautiful warm yellow. The small, creamy-white flowers are clustered into an upright, cone-shaped inflorescence that reaches 15 cm (6 in.) in length and develops into very sparse prickly fruits. One caution here: all parts of this tree, including the fruits, are poisonous.

Bergenia cordifolia is well known to gardeners throughout the temperate world. Native to Siberia, it can tolerate zone 3 and warmer. A clump-forming evergreen perennial, its rounded, leathery leaves are up to 30 cm (12 in.) long. In summer they are a glossy green but become tinged attractively red during winter. The thick, almost succulent leaves persist under snow, and welcome the sun as the snow melts above them. Then the plant sends up 30- to 60-cm (1- to 2-ft.) red stems carrying clusters of dark-pink flowers.

Bergenias withstand extremely cold temperatures yet have an astounding tolerance of summer drought. They certainly don't seem to be fussy about soil types.

In the exquisite Japanese Garden at the University of Alberta Devonian Botanic Garden are mass plantings of bergenia among rocks. The sight of this in bloom - creating a 2-m (6-ft.) wide burst of pink blossoms in a northern spring certainly lifts one's spirits.

Clematis tangutica, the famous "lemon peel" clematis, is incredibly hardy. I well remember seeing it flourishing and full of bloom on the west wall of a house in Whitehorse. It comes from western China and is hardy to zone 2 and up. This is a vigorous climber or sprawler (it looks nice either way). The flowers appear later in the season and are abundantly borne on solitary stems in a Chinese-lantern shape 4 cm (1.5 in.) long. The bright lemon-yellow petals are thick and leathery to the touch. As the flowers fade they produce fluffy seed heads that stay on all winter long. It looks great on a trellis but can look even more attractive if allowed to climb up through the lacy branches of a weeping caragana.

In some places this clematis can be a bit invasive - in Alberta it is quite widely distributed on the banks of the North Saskatchewan River - so keep it in check and pull up any unwanted seedlings.

Delphinium hybrids seem to love colder climates. I was absolutely taken by the fact that they happily seed themselves about and flourish in the ditches of Dawson, the home of the gold rush in the Yukon.

There are, of course, many hybrids of delphinium on the market under such cultivar names as 'Blue Bees,' a superb pale baby blue, or 'Blue Nile,' which has deep sky-blue flowers with tiny white centres. They have typical deeply lobed buttercup-like foliage and flower spikes up to 2 m (6 ft.) in height.

There are two factors for happy delphiniums: rich soil and guaranteed snow cover. This explains why they do so well in the ditches up north. So add plenty of compost at planting time, then top-dress with a 10-cm (4-in.) layer of compost every spring.

Most winters up north get good snow cover, but with weather being so unpredictable everywhere these days, it is best to be prepared and cover clumps of delphiniums with chicken wire, twigs and leaves. Of course, you must wait until after the first couple of frosts before doing this, otherwise every little mouse and vole will be in there for the winter, feeding on the plants you are trying to protect.