The first hard frost changes the garden. Leaves stiffen. Canes darken. Temperatures rise and fall. The ground begins to freeze and thaw. It is time.
Most roses can withstand a quick cold snap of temperatures down to 10 degrees F, but it is best to protect them if you expect an extended period of time when temperatures dip under 20 degrees F. The amount of protection your roses need depends on the climate in which you live. Winter rose care begins after the first hard frost. Protection is not dramatic. It is steady.
In northern areas in Zone 4, winter rose care begins around mid October and if possible before the first snowfall. The first step in protecting bush type roses such as hybrid teas, floribundas, and grandifloras is to loosely tie the canes together to keep them from whipping around in the wind. Then cover the base of the plant with 12 inches of soil. Straw or leaves can be placed over the soil mound for additional insulation. The soil mound looks plain. It works.
If you prefer to use styrofoam rose cones, prune the bushes back so the cone will fit over the plant. Before you cover the bush, mound several inches of soil around the base of the canes, then place the cone over the rose. To keep the cone in place, mound soil around the outer base. It may not look like much in winter, but roses do not need to look like much in winter. They need to rest.
To protect climbing roses, remove the canes from their support and carefully bend them to the ground. Hold the canes in place with pegs or stakes and cover with several inches of soil. This should be done after the roses go dormant and have been exposed to two or three hard freezes. Dormant does not mean gone. It means waiting.
Remove protective materials before the buds break open, normally in late March to mid April. Buds break quickly once they decide to grow. Timing matters.
In Zone 5 or 6, since the winters are not as severe, you can protect your roses as mentioned above or simply pile protective material around the base of the plants. Another option is to create a chicken wire cage filled with leaves around the base. Your main concern is protecting your roses from extended periods of weather below 20 degrees, winter winds, and fluctuating temperatures. Fluctuating temperatures are often the real problem.
In Zone 7 and 8, the biggest danger to roses is when temperatures rise and fall causing the ground to freeze and thaw. This often results in frost heaving of the roots from the ground. To prevent that from happening, mound at least 2 to 3 inches of mulch around the base of the rose. Keep the mulch away from the trunk of the plant so you do not attract rodents and insects. The aim is simple. Keep the roots steady.
Potted roses are another matter. Roots in containers lack the natural shelter of ground soil. Repeated freezing and thawing is what kills roses, and potted roses are especially susceptible because their roots are above ground in a pot. The culprit is freezing and thawing. Bring them in before the roots freeze in the pot. Do not let them freeze first and then bring them in the garage to thaw them out. Let the plants drop their leaves naturally.
In places like Minnesota, gardeners have learned to take winter seriously. Some of the harshest winters in the lower 48 states have shaped ideas of winter rose protection. After watering the pots and cutting the canes back to about 10 inches, move them to an insulated but unheated space where they can rest for the winter. An unheated but insulated garage can work.
Line the back and floor of a corner with foil faced roll insulation. Wedge foam insulation along the back wall and place another piece on the floor so the pots are separated from the concrete. Wrap foil around each pot and make a small cap to cover the canes. Push the pots together tightly inside the insulated space. Cover the top with another piece of foil and tuck it into place. Darkness throughout their dormant period is part of the protection. Water the plants before enclosing them, but do not soak them. Halfway through the dormant period, you can open them a bit and add a little more moisture so they do not completely dry out.
Some gardeners remove small plants from each container after they are completely dormant in late November, shake off most of the soil, bundle them together, pack them in large plastic tubs, and cover with wood chips. Four months later they unpack healthy undamaged budded root stocks and repot them in fresh potting soil. Others use a thick vinyl bag designed for construction debris. After punching drainage holes in the bottom, fill it with potted roses and cover them with wood chips. The tall sides help prevent tiny intruders from camping out for the winter.
Covering container roses with organic material such as wood chips, chopped leaves, seaweed, or manure can provide a winter place for mice and voles. Roots and bark are vulnerable in winter. Protection must consider rodents as well as cold.
Whether you are tying canes in Zone 4, piling leaves in Zone 5, mounding mulch in Zone 7, or building an insulated shelter in a garage in Minnesota, the purpose is the same. Keep the plant dormant. Keep it from repeated freezing and thawing. Hold it through the cold.
When spring returns and the buds begin to swell, remove the coverings before the buds break open. Move the pots back into the light. The roses emerge to grow and bloom another year.
Winter is not the end of the garden. It is a period of rest. Roses die back to their level of coverage and are pruned back to the still living cane wood in spring. They return.
That is enough.
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