Roses need special care to survive winter in Colorado. Insulating roses from temperature fluctuations helps their natural defense system operate properly. It’s not cold weather that damages roses; it’s the see-saw slide between warm and cold days and nights.
Proper winter rose protection should actually begin at the end of August. Stop fertilizing at this time and gradually reduce water. Roses will begin the hardening off process which prepares them for dormancy. In November, once night temperatures have consistently dipped to 20 degrees, prepare roses for winter. Cut down any high canes that could break in high winds or heavy snow. But don’t do any serious pruning until mid- April.
Once the rose is dormant, it can withstand very low temperatures without harm. In our climate with temperatures fluctuating as much as 40 degrees in one day, roses can come out of dormancy. That’s when damage can occur.
For hybrid teas or grandiflora roses, 12 inches of mulch contained by a plastic rose ‘collar’ or a wire mesh cylinder will keep roses in dormancy. There are many good mulches available, but some gardeners like to combine shredded leaves with soil from summer containers as a cost effective mulch. In December strip away dead or diseased leaves from the branches and clean up any debris around the base of the rose so diseases won’t survive winter.
Most miniature roses are very hardy. Because the plants are usually small, they are easy to protect. Mound mulch around the stems to a depth of 5 to 7 inches. Chipped evergreen boughs or loosely packed straw are good mulches for miniature roses.
Because of their height, protecting climbing roses can be challenging. Many gardeners mulch the graft area and tie the canes firmly in place. This is the easiest method. Other gardeners take the climber canes off their supports after they are dormant and secure them to the ground. The canes are then totally covered with mounded mulch. This is a more complex method.
Finally, remember to water roses during extended dry spells.
“November and December Tips,” by Barbara Kemp, The Denver Rose Society, www.denverrosesociety.org/home_page/11RoseGrowingTipForNovember.pdf
Planttalk #1726 – Roses: Winter Care
“Winter Protection for Your Roses” by Stan Barrett, Colorado Master Gardener, www.colostate.edu/Dept/CoopExt/4DMG/Flowers/Roses/wintrose.htm
Contributed by Eileen Tully, Certified Colorado Gardener
Photo courtesy of Colorado State University Extension, Tri River Area