AMES, Iowa — Roses must be protected against not only low winter temperatures, but also fluctuating temperatures and winter winds. Horticulturists with Iowa State University Extension and Outreach explain how to protect roses against winter injury. To have additional yard and garden questions answered, contact the ISU Hortline at 515-294-3108 or email email@example.com.
Most hybrid tea, grandiflora, floribunda and other modern roses require protection during the winter months. Low temperatures and rapid temperature changes in winter can severely injure and sometimes kill unprotected modern roses. (Most old garden roses possess excellent cold hardiness and don’t require winter protection.)
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 helps 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 hybrid tea, grandiflora and floribunda roses for winter after the plants have been hardened by exposure to several nights of temperatures in the low to mid-20s. Normally, this is early November in northern Iowa, mid-November in central areas and late November in southern counties.
A rose growing in a pot may be destroyed if the potted rose is left outdoors on a deck or patio over winter. Potting soil temperatures in containers left above ground are likely to get extremely cold, damaging or destroying the roots of the rose.
To protect a potted rose, dig a hole in the ground in a sheltered location. Set the pot in the ground and then place soil around the pot. Place additional soil over the rose, covering the bottom 6 to 8 inches of the rose canes.
Potted miniature roses also can be brought indoors before a hard freeze in fall and placed in a south or west-facing window and maintained as a houseplant.
The best way to prevent rabbit damage to roses in the home landscape is to place chicken wire fencing or hardware cloth around the plants. To adequately protect plants, the fencing material needs to be high enough that rabbits won’t be able to climb or reach over the fence after a heavy snow. In most cases, a fence that stands 24 to 36 inches tall should be sufficient. To prevent rabbits from crawling underneath the fencing, bury the bottom 2 or 3 inches below the ground or pin the fencing to the soil with u-shaped anchor pins.