Dr. Leonard Perry, Horticulture Professor Emeritus
University of Vermont
While tea roses and a few other types usually don’t survive in cold climates, many of the new series, as well as some of the older shrub rose cultivars (cultivated varieties), can survive cold winters with some protection. While these methods don’t guarantee that your rose plants will survive, they’ll surely help those that are marginally hardy.
Roses can be killed or injured during winter in several ways:
direct injury to tops or roots from extreme cold; rapid
temperature changes; root injury from drying out as a result of
plants being heaved by alternate freezing and thawing; injury
caused to stems by mice living under snow or in straw around
plants; and snow or ice breakage.
Injury from extreme cold can be avoided only by selecting hardy
cultivars. As a very general guide, roses with small blossoms
tend to be hardier than the largest flowering types. Most hybrid
tea roses are less hardy than the grandifloras or floribundas. In
addition, some climbing roses and many old-fashioned shrub
cultivars tend to be hardy as are some series such as the Explorer
roses that were originally bred in Canada.
Whether a rose survives, as with other perennials, depends in
part on the microclimate”—the immediate area where it is planted.
Adjacent to the warm south-facing wall of a building, or a slope
facing north and exposed to winds, are all examples of
microclimates. Even with a cold climate, or microclimate, proper
winter protection can help plants to survive.
For shrub varieties, start by mounding soil or compost 10 to 12
inches around the base of the plants. Then, add another 12 to 16
inches of mulching material such as leaf mold, straw, or pine
needles over the mound to help stabilize soil temperatures. This
extra protection means less freezing, thawing, and subsequent
heaving out of the soil. If you have many mice around, you may
want to skip the mulch materials as they provide a winter home and
ready food source in your rose stems. Ideally, mounding should be
applied in mid to late November. Earlier application may slow
development of stem maturity and hardiness.
If you have rabbits living in your landscape or nearby, you may
want to surround your rose bush with a wire cage, especially if
canes will be exposed and above the usual snow depth. Smaller
mesh chicken wire usually is sufficient, but can be chewed by a
hungry rabbit. Heavier gauge rabbit fencing, or hardware cloth,
provide better protection. You may want to install this first,
then add your compost or soil within the cage frame.
You may need to prune the canes back to the surface of the mulch
for ease of covering, but don’t cut back any further. Wait until
spring, so you can see which canes or parts of canes have died,
then cut them back. If the winter is mild, or your mulching is
thick, you may have to cut back very little.
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