Location
Type Protection
Climbers
Location
In most areas of the country roses will need some kind of cold or freeze protection. Since I live in the deep south I don't have to worry about this aspect of growing roses, but for those who do let's see if I can give some pointers on how to best care for them during this time. The amount of protection you should do is proportionate to the average temperature you experience. Roses can handle temperatures down to 20º for short periods of time. Anything colder than that could result in some damage to most plants. It is best to protect your plants if you have temperatures below 28º. Also important is the variety or cold hardiness of the plants you have. Some varieties of roses don't handle cold weather very well. Usually shrub roses, climbers, miniatures, and some hybrid teas winter well.
Type Protection
I've heard that the best protection for roses during the winter is a good blanket of snow. This protects the canes from freezing and drying out or warming up to the point they want to start growing too early. It will also protect from damaging wind that will sap the moisture out of the canes. One of the biggest problems with snow is the weight of snow may break the canes if they are not protected.
Where snow is not deep enough all winter, or comes and goes you will need to rely on additional means of winter protection. There are several ways this can be done. Obviously covering the plants with some sort of insulating material such as a large container would protect them from the elements, however this would be a large undertaking if you have a sizable rose garden. If this is done it should remain until spring when it should be removed gradually if possible to reduce the chances of damaging new growth should a late cold snap come.
The traditional way of protecting roses for winter is mounding soil over the base of the canes approximately 12" to 14" deep. This will protect the bud union from frost damage. Most people don't like to do this because it takes a lot of time. The dirt has to be brought in for the winter and taken out in the spring. Another, less time consuming, protection is a type of winter mulch that can be worked into the soil in the spring for soil improvement.
In areas of the country that stay below -10º for long periods of time special rose caps or rose cones can be used. These are made of thick-walled polystyrene that taper toward the top. Some have covers that can be removed or opened to prevent early growth on warm days. Another cover type is to enclose the plants in an open top cage filled with shredded organic material.
In the very cold areas a technique is used called the Minnesota freeze protection. First the canes are tied together then on one side of the plant the roots are cut. A trench is dug to accommodate laying the plant down, carefully so the roots on the other side of the plant are not damaged. Then the entire plant is covered with an organic material such as oak leaves mounded18" to 20" deep.
Climbers
When climbers need protection they can be removed from their trellis, staked to the ground and covered with some type mulch. In early spring remove the protection and tie the canes back to their support. Another protection for climbers is to wrap them with burlap, however , this is very cumbersome.