Most hybrid tea, grandiflora, and floribunda roses require winter protection in Iowa. The low temperatures and rapid temperature changes in winter can severely injure and sometimes kill unprotected roses.
Hilling or mounding soil over the base of each plant is an excellent way to protect hybrid tea, grandiflora, and floribunda roses. 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. A small amount of soil placed over the straw or leaves should hold these materials in place. Prepare roses for winter after plants have been hardened by 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.