Although Gertrude Jekyll, English plantswoman par excellence, was unlikely to imagine the cold in a typical Canadian winter, she did recognize the superior hardiness of R. rugosa hybrids, advising (in her book: Roses for English Gardens, 1902), “The great hardiness of the rugosas enables them to be used in exposed places where many kinds of roses would be crippled or would perish.” Nearer in time and closer to home, Jan Mather, author of The Prairie Rose Gardener (1997) lists 28 R. rugosa hybrids, all with cold hardiness to Zone 2 and most with repeat bloom. Among them is a great favourite of mine, ‘Thérèse Bugnet', bred in Alberta, with deep raspberry-tinted canes and double, fragrant pink flowers. Another familiar rose is ‘Blanc Double de Coubert' (Zone 2), a strongly scented white rose (reputedly much admired by the late Queen Mother) that regrettably I struggled to remove (yes, it's true) because its vigour knew no bounds. ‘Dart's Dash' (Zone 2), a semi-double, reddish violet flower with strong perfume, is more constrained and has the dividend of ornamental hips in autumn. The taller, clove-scented ‘Hansa' (Zone 3) with soft magenta petals, and semi-double ‘Jens Munk' (Zone 2), with clear pink flowers, both make good flowering hedges at the back of a border.
The Explorer and Parkland series roses, expressly bred for the Canadian climate, are generally categorized as shrub roses. Among them is a new 2005 introduction, ‘Morden Belle' (Zone 3, to 1 m), with double, pink flowers and glossy leaves. An older cultivar and a real beauty with Old Rose style, ‘Morden Blush' (Zone 2, 1 m) is very double and scented, with quartered, pink-ivory petals and a button centre. It has the longest blooming period of the Parkland roses, and its height makes it perfect for garden borders. ‘Cuthbert Grant' (Zone 2), named for a famous leader of Manitoba's Métis, is similar in size, with deep red flowers in hybrid tea style.
The Iowa-bred Buck roses (all Zone 4) are also popular shrub roses in Canadian gardens, including pink ‘Carefree Beauty', and ‘Applejack', with intensely fragrant petals of rose pink tinged with crimson. ‘Folksinger' has slightly cupped yellow flowers flushed with apricot, and ‘Pearlie Mae', huge clusters of blended yellow-and-pink bicoloured blooms.
When planting grafted roses in cold zones, be sure to set the bud union five to 10 centimetres below the surface of the soil. Be prepared to water weekly and more often during dry spells, wetting the soil to a depth of at least 45 centimetres. (Moisture stress erodes winter hardiness by interrupting biological processes necessary to store carbohydrate energy and harden wood.) It may not be necessary to provide winter protection to reliably hardy roses, but if you want to give them a light blanket of added winter insurance, pile leaves around the base of each plant and hold them in place with shrubby sticks and evergreen boughs. In spring the leaves can be spread out as mulch around each plant.