Iowa's winter weather can be brutal. Most modern roses grown in the state require winter protection. Exposure to low temperatures and rapid temperature changes can severely injure and sometimes kill unprotected roses.
Bush-type roses include hybrid teas, floribundas, and grandifloras. An excellent way to protect bush-type roses is by hilling or mounding soil around the base of each plant.
Begin by removing fallen leaves and other debris from around each plant. Removal of diseased plant debris will help reduce disease problems next season. Then loosely tie the canes together with twine to prevent the canes from being whipped by strong winds. Next, cover the bottom 10 to 12 inches of the rose canes with soil. Place additional material, such as straw or leaves over the mound of soil. The straw or leaves can be held in place with chicken wire fencing or by placing a small amount of soil over the materials.
Most climbing roses bloom on the previous season's growth. Unfortunately, the canes of many climbing roses are highly susceptible to winter injury. If much of the plant is destroyed during winter, these types of roses produce few, if any flowers.
To protect climbing roses, remove the canes from the trellis or support and carefully bend them to the ground. Hold the canes to the ground with pegs or stakes, then completely bury the canes with several inches of soil.
Tree or standard roses are produced by bud-grafting the desired rose variety onto a tall stem. Since the cold-sensitive bud union may be 2 or 3 feet above the ground, tree roses are extremely vulnerable to winter injury or death. (Tree roses are best suited to areas with mild winter climates.)
The first step in protecting a tree rose is to decide which direction to lay the plant. Then loosen the soil in the opposite direction with a spade. Put the blade into the soil about 1 to 1 1/2 feet from the base of the stem. Then gently rock the spade back and forth to loosen the soil and free the roots. Loosen the soil in a semicircle around the plant. On the other side of the tree rose, dig a trench to accommodate the plant and then carefully bend the trunk (stem) down to the ground. Peg the stem down with stakes. Finally, completely cover the tree rose with several inches of soil.
Roses in Containers
Roses growing in pots or other containers also need winter protection. To protect potted roses, dig holes in the ground in a sheltered location. Place the pots in the ground. Then cover the roses with soil. (Potted miniature roses can also be brought indoors in the fall and placed in a south or west-facing window and maintained as a houseplant.)
Prepare roses for winter after plants have been hardened by exposure to several nights of temperatures in the low to mid-twenties. Normally, this is early November in northern Iowa, mid-November in central areas, and late November in southern counties.
This article originally appeared in the 11/7/2003 issue.