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Winter Hardy Roses

By Christie Hale, Colorado Master GardenerSM, Colorado State University Cooperative Extension, Denver County

Growing roses in Colorado can be a challenge with our extreme temperature fluctuations and long periods without rainfall. 

For better chances of success, avoid planting varieties inappropriate for our climate such as many hybrid teas, grandifloras and floribundas. They require a great deal of care and may die even with winter protection. Consider planting roses grown on their own roots that are better adapted to our growing conditions. If the rose dies back to the ground, it will still come back true to the variety. When a grafted rose dies back to the ground the only thing that usually survives is the rootstock. Grafted roses can also send up suckers from the rootstock that can outperform the desired rose. 

A group of winter-hardy roses that perform well in Colorado’s climate are the Explorer and Parkland series. These rose cultivars are offered from Agriculture and Agri-Food Canada, Horticulture Research and Development Center. They are hardy down to –35 degrees C without winter protection other than snow. The roses are disease resistant, flower repeatedly throughout summer and require minimal pruning. Best of all, they come in a wide range of colors and shrub size. To ensure their hardiness, they are best grown as own-root roses.

 There are more than 24 winter-hardy roses from the Explorer series and ten from the Parkland series. A few of these are mentioned here.

Explorer series roses: climbers or shrubs taller than six feet, suitable for tying to supports

  • William Baffin. A vigorous, upright and strongly arching climber. It flowers freely and is highly resistant to blackspot and powdery mildew. The flowers are a strawberry pink, with an average of 20 petals. Blooms are loose and carefree. It forms a dense, full shrub, perfect for a tall hedge. There is little or no winter dieback of canes. This may be the toughest of all the Canadian explorer roses. It reaches a height of 8-10 feet.
  •  John Cabot. A robust, upright, arching shrub, reaching a height of 6-9 feet. Flowers are a deep, rosy pink, with an average of 40 petals. It has a long bloom season and is very resistant to disease. Some spring pruning will be required after a severe winter.
  • Henry Kelsey. (shown above) A shrub with long arching canes that can be tied and used as a climber. Blooms are vivid red, semidouble with showy golden stamens. This rose is resistant to powdery mildew and shows moderate resistance to blackspot. It will grow to 6-7 feet tall. 

Explorer series roses: tall shrubs up to six feet

  • Alexander MacKenzie. An upright, vigorous shrub that will grow to 6 feet x 4 feet. It is highly resistant to blackspot and powdery mildew. Flowers are deep red with 40 to 50 petals. The flowers closely resemble a hybrid tea rose.
  • John Davis. Flowers are medium pink with an average of 40 petals. The semi-double blooms resemble old-fashioned roses. The bush is vigorous, disease resistant and somewhat sprawling and will reach a size of 5 feet x 7 feet. It flowers freely and is very winter-hardy.

Explorer series roses: low shrubs growing up to 4 feet

  • Henry Hudson. A rugosa hybrid, semi-dwarf shrub that is repeat flowering and highly resistant to blackspot and powdery mildew. The flowers are white tinged with pink, with 20 petals. This is a very dense vigorous shrub that is exceptionally hardy. It will spread by suckering, like most rugosas, so it is best to plant where this is desired. It reaches a height of 2 feet and will spread to 3-4 feet through suckering.
  • Royal Edward. A semi-miniature low spreading rose that grows to 18 inches x 22 inches. Repeat flowering with good disease resistance. The buds are deep pink, but open to a medium pink and later fade to pale pink. Flowers have an average of 18 petals and are borne in clusters. Only light pruning is required in spring.
  • George Vancouver. This shrub has an upright growth habit with good disease resistance. It reaches a mature size of 3 feet x 3 feet. The deep red bud opens to medium red and fades to pink once fully opened. Flowers have 24 petals and are produced in clusters.

Parkland series roses: low shrubs under 4 feet

  • Morden Blush. A hardy, low-growing, everblooming shrub, reaching a size of 2 - 3 feet x 2 - 3 feet. Plants tolerate high summer temperatures and are moderately resistant to powdery mildew and blackspot. This rose has the longest flowering of any prairie-developed shrub rose. Flower color is variable depending on temperature. In cooler temperatures blooms are a light pink. In warmer temperatures the blooms are ivory to white. Flowers resemble old-fashioned types of roses when open.
  • Morden Centennial. Flowers are medium pink with about 40 petals. The shrub is hardy with good disease resistance. Deadheading will encourage rebloom. It reaches a mature size of 4 feet x 4 feet.
  • Winnipeg Parks. A dense, hardy shrub that grows to 2 feet x 2 feet. The flowers are a beautiful scarlet red, with 22 petals and produced in clusters. The shrub has moderate to good resistance to powdery mildew and blackspot. Winnipeg Parks has the most attractive foliage of the Parkland roses.
  • Hope for Humanity. A low-growing everblooming shrub. The bush has an open habit with good cane strength. Flower buds are a deep wine red, opening to a double blood red flower. The shrub shows good resistance to powdery mildew and rust, and a fair to good resistance to blackspot. This is a very hardy shrub that requires no additional winter protection. It will reach a size of 2 feet x 3 feet. 

To find out more about winter-hardy roses the following books contain a wealth of information. Hardy Roses, An Organic Guide to Growing Frost- and Disease-Resistant Varieties, by Robert Osborne, Garden Way Publishing; Easy Roses for North American Gardens, by Tom Christopher, Reader’s Digest; and Roses for Dummies, by Lance Walheim and the Editors at the National Gardening Association, IDG Books Worldwide, Inc. 

For additional information and to purchase these and other varieties of winter-hardy roses contact: High Country Roses, 800-552-2082, www.highcountryroses.com or Spring Valley Roses, 715-778-4481, www.springvalleyroses.com. Both specialize in hardy roses that are grown on their own roots. Also check local greenhouses for availability.

Photo: Judy Sedbrook

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Date last revised: 01/05/2010