Proper care keeps your rose plants healthy and disease-free during the growing season. This increases the winter tolerance of your rose plants. Roses need protection in order to survive winter conditions in most areas. The best time to winterize is in late fall once your rose bush has gone dormant. In a container, a rose plant's roots are in danger of freezing. A rose bush planted in the ground has the insulation of the surrounding soil for protection. As the air around the container drops, so does the temperature of the rootball.
Cut the rose canes back to a length of 30 to 36 inches with clean, sharp pruning shears. Remove any dead canes.
Tie the tips together with a strong piece of twine to help reduce breakage during winter storms.
Remove dead and fallen leaves from the container. Discarding the debris from the rose plant will help get rid of any plant disease or pests hiding in the leaves.
Dig a trench in the ground that is as wide as the container and just as deep. Place the rose plant into the trench and water well. This is to prevent the soil from going bone dry during the winter.
Cover the container with mulch or soil to protect the root system. Some mulches to use include leaves, straw and wood chips. Once the trench is filled in, then create a 12-inch tall mound of mulch that is 12 inches wide covering the bottom portion of the rose plant.