Beth R. Jarvis
Hardy roses are ideal for gardeners who love roses but don't want to protect them. While few roses are immune to winter injury, many do not suffer significant dieback. This brief focuses on cultivars and species that suffer little or no dieback or, if grown on their own roots, have the ability to regrow and bloom on new wood after most or all of their tops have been killed by winter cold.
When shopping for hardy roses, ask if the plants are "own root", "grafted" or "budded." Roses growing on their own roots will grow back true to type. When grafted or budded plants send up suckers (canes that sprout from underground), those suckers will likely be from the rootstock rather than the desired cultivar that has been grafted onto the roots.
Don't assume that all shrub roses, old garden roses, species or other hardy roses are grown on their own roots; quite a few hardy roses are grafted or budded. In a cold climate like Minnesota's, "own root" plants are insurance against extraordinarily harsh winters. Their only disadvantage is that some cultivars sucker so profusely that they may spread too much or even become invasive.
Many roses bloom on new wood, which means the flower buds are initiated in spring. A hard winter will not reduce the number of flowers such cultivars produce. Other cultivars, however, bloom on growth with flower buds initiated the previous summer. Flower buds on those roses may be killed in a harsh winter, resulting in little or no bloom the following summer. Many climbing roses fall into this category.
Roses thrive in well-drained soil of any type with a pH of 6.0-7.0. For best results in poorly drained clay soils, make a raised planting area. Spread 2-4 inches of compost or peat over the area to be planted and mix it in well. Dig generous holes to accommodate the plants' roots.
Hardy roses will grow and bloom well if you:
Although many hardy roses are quite disease resistant, you can minimize fungal diseases such as powdery mildew and blackspot if you water only at the base of the plants or wet their foliage early enough in the day so it dries by nightfall. Many rugosa cultivars should not be sprayed with fungicides because the chemicals will burn the foliage and possibly even defoliate them.
A number of new hardy roses have been released through two Canadian breeding programs over the past 20-30 years. The "Explorer Series" and "Parkland Series" were developed by Agriculture Canada in Ontario. The developers of these roses intended that they be grown on their own roots so that if their tops were killed by winter cold, they'd be able to send out suckers from their roots in spring and flower on new growth that summer.
A number of other groups of roses touted as "hardy" lack the hardiness to survive most Minnesota winters unprotected. A warmer microclimate, such as along a house wall, may give marginally hardy roses an extra bit of protection and enable them to survive.
The Meidiland (MAY-dee-land) roses are marginally hardy in USDA Zone 4 and need some winter protection. Ferdy, Bonica, Royal Bonica, and Sevillana are part of this series. David Austin's English roses also lack sufficient hardiness for Minnesota, although some may eventually prove to be hardy here. The same is true (with a few exceptions, such as "Carefree Beauty") of the roses developed in Iowa by Dr. Griffith Buck. Nor are the Simplicity, Freedom, or Robin Hood roses, often sold for hedges, hardy enough for Minnesota.
Minnesota extends into three USDA zones. The lower third of the state is in zone 4, the upper two thirds are largely in zone 3 but southern Lake of the Woods County, northern and eastern Beltrami County and a portion of northern St. Louis county are in zone 2.
List of hardy roses available to Minnesota gardeners.
The authors wish to thank David Zlesak, Department of Horticultural Science, University of Minnesota, and Doug Foulk, Minnesota Extension Service, for their assistance.