Garden roses vary in their endurance to winter conditions. Shrub and rose species are generally the hardiest and require no protection, even in the coldest sections of the country.
In regions where the temperature is likely to reach zero, growing the bush roses will likely need protection. If the temperature goes below zero, then protection is essential.

What Causes Winter Injury?
Winter injury is due to cold. Ice crystals form in the minute spaces between the stem cells when the temperature falls below freezing.
As the cold increases, the ice crystals increase in size by drawing water from the surrounding cells, which begin to shrink.
At very low temperatures, the ice masses inside the stem become so large that the tissue is pushed out of the normal arrangement and often torn.
If thawing occurs slowly, the cells reabsorb the water released from the melting ice crystals.
When the rupturing of tissue has not been severe, the stem recovers completely.
Fluctuating temperatures increase damage.
One drop to zero will not seriously harm a mature, well-hardened, hybrid-tea stem, but if the stem thaws and the temperature drops again to zero, the injury may kill the cane.
In this way, comparatively mild winters often damage more than consistently cold ones.
Repeated freezing to ten degrees above zero, with thawing periods between, will often kill the canes that are not protected.
Canes Die from Inside Out
The hot, drying spring winds have often been blamed for injuries, but research does not bear out this idea.
Since canes were previously injured by cold and lost water rapidly during warm spring weather, it appears that the harm was done at this time, but actually, it occurred in the winter.

Strangely enough, different tissues in the stem vary in their resistance to cold. The pith is killed first.
The outer green bark stands at a much lower temperature, so externally, the stem appears uninjured, although the inside wood and pith are dead.
If the stem is cut, the pith will-be brown, the wood. may also be brown or at least show dark, radial streaks. Such a stem will not sustain new growth.
Summer Factors Affect Winter Hardiness
Certain summer factors affect winter hardiness.
A vigorous plant that has retained its leaves throughout the summer and matured gradually in the fall will come through a severe winter with little injury.
A close correlation exists between disease, especially blackspot, and winter killing.
When the disease is serious in summer, severe winter injury invariably follows.
Keeping rose plants healthy is, therefore, the first step toward safe wintering.
Leaves must be retained in summer because the leaves manufacture the sugar and starch, which, stored in the stem, promotes hardiness in the plant.
Other factors affecting cold resistance are the following:
- Poor drainage
- Late or over-fertilization
- Drought
- Overcutting of blooms
- Too much shade
Severe cold early in the fall before plants are hardened is also devastating but will not necessarily kill the plants.
Related: Tips On Rose Watering, Fertilizing, Pruning, and More
Why Winter Protection?
Winter protection aims to keep the temperature from going below the danger point and prevent alternate freezing and thawing.
The most effective method is to mound soil around the base of plants and to cut back or stake any canes over 30” inches on hybrid teas, polyanthas, and floribundas.

Then plants will not be whipped about by the wind, and roots will loosen from their soil anchorage.
Make the soil mound as high as possible, at least 8” inches.
Bring this earth in from a vacant lot, the vegetable garden, or your compost pile.
Lightweight vermiculite rose mulch which you buy at a local garden center, is even more convenient.
Some rosarians get mounding soil from a deep trench along the back of the bed, but this must be at least 3’ feet from the plants so that roots will not be exposed or water will drain in and freeze close to them.
Begin mounding after the first killing frost. After a few heavy spots of rain and before the soil freezes, inspect the plants.
If the soil has settled or washed away, hoe more back, and do this again, if necessary.
In climates where normal temperatures do not drop below zero, no other protection is necessary nor of any special advantage.
Soil mounds keep the temperature of the covered canes from falling below the killing point.
The beat is conducted upward from the warmer layers below.
Even though the soil seems frozen solid, the temperature 2” inches below the surface rarely goes below 20° degrees Fahrenheit, even in the coldest regions.
Normally it ranges from 28° to 30° degrees Fahrenheit, even though the air temperature may be down to zero.
The soil mound protects only the lower part of plants but ensures against complete loss.
Even though they kill back to the top of the mound, enough wood survives to give the plant a good start in spring and the chance to rebuild itself.
With below-zero temperatures, some injury to the tops is bound to occur.
Where temperatures of ten below are expected, provide additional cover.
Use anything that will not hold moisture—evergreen boughs, marsh hay, or coarse straw. Leaves are not so satisfactory because they get soggy.
However, oak leaves or strawy manure can be used to fill in the space between the mounds and hold them in place.
The purpose of the extra coverage is not so much to protect tops as to insulate the soil mounds and keep them from washing away.
The shading and windbreaker effects of deeper mulch are also beneficial.
Protecting Climbers
- Climbers will stand the considerable cold when protected by buildings or close fencing.
- In general, where zero temperatures occur, a soil mound around the base is desirable. Then if the tops are injured by the cold winter, the plants will not die.
- If 10° degrees Fahrenheit below is likely, remove the canes from their supports and lay them on the ground.
- Pin them close to the surface with wire pegs or place boards and bricks on top. In very cold areas, cover the entire plant with soil.

How To Protect Tree Roses?
Tree or standard roses will not stand as low temperatures as other rose types.
Where as low as 15° degrees Fahrenheit is likely, lay them over on their sides and cover them with soil.

Usually, it is necessary to dig under one side of the plant to bend it over far enough to cover it without breaking the trunk.
Pruning tops back 12” to 15” inches will make it easier to cover them.
In the spring, do not be too big a hurry to remove winter protection, but do not put it off too long.
However, it is better to be early than late because the soil mound, which in spring is much warmer than the air, stimulates growth.
Then shoots starting below the mound are easily injured. Removing soil before growth occurs delays buds until conditions are safe for them.
Let the weather guide you. As soon as the danger of a hard freeze seems to have passed, remove the soil mounds.
There is some merit in removing protective material gradually, but this is a matter of practicality.
There is little likelihood of damage if you take it off all at once. Handle carefully the canes that have started growing.
Don’t be too worried if there is a late spring freeze after new growth is well developed.
One freeze is not serious, except that it delays flowering. Although two or three may have a weakening effect, two or three are unlikely.
If you have only a few plants, you can cover them with peach baskets or newspaper when frost warnings are given.
Related: Winter Protection for Roses

Rodents Damaging Roses During Winter
Field mice sometimes cause winter damage of another kind.
When mulch is used or plants are buried under deep snow, guard against cany girdling if rodents abound in the garden.
Place poisoned grain among the roses and especially around the climbers.
You can obtain this bait from seed, hardware, or department stores.
To attract the mice, the poisoned grain must be dry, so place it in glass jars or soup cans and lay them on their sides in protected spots around the roses before you put on the mulch.
A piece of board or shingle laid over the container will keep out the rain and still not prevent the mice from reaching the grain.
Rabbits may also cause damage in winters of heavy snow. A wire fence around the garden or enclosing the rose beds is the only sure protection.
44659 by Dr. R. C. Allen