How you prepare roses for winter depends to some extent on what kind of roses you are growing. Most shrub roses and rugosa roses are very cold hardy and do not require additional protection, while some hybrid tea roses can be severely damaged and require some effort to get them through cold winters unscathed. Roses grown in our area should be winter hardy to at least USDA Zone 8. Gardeners in urban areas can often get away with Zone 6 or even Zone 7 plants, but resign yourself to the fact that they could be lost if we experience an abnormally cold winter. Current forecasts call for a mild winter, but it could change…
All plants survive winter better if they are completely dormant when severe cold arrives. Avoid fertilizing roses after mid-October to avoid causing them to push new growth that may not harden off soon enough. Tender, new growth is more likely to be damaged by a sudden drop in temperature than mature growth. Quit deadheading (removing spent flowers) or pruning in any way after mid-September for the same reason.
Finally, healthy roses are in much better shape to survive cold winters. Protect them from insect and disease problems and apply additional water during the hot, dry summer weather. Severe cold can be the last straw for roses stressed by these factors.
Wait until roses are dormant and have dropped most of their leaves before cutting them back or applying winter protection. Because most roses will experience some winter damage that will have to be pruned out in spring, keep pruning to a minimum except as required to reduce climbers to a manageable size or fit the plant under a cover.
Rake up and remove fallen leaves, especially if diseases such as black spot or powdery mildew have been a problem. This reduces the amount of disease-causing spores present to cause problems the following year. You will probably still need to make fungicide applications in spring to protect susceptible roses from disease, but the pressure will be slightly less if you remove diseased leaves now.
For hybrid tea roses, mound about 8 inches of soil up over the crown to protect the graft union and ensure that the variety survives the winter, not just the rootstock. Be sure to pull the soil from other areas of your yard and not from around the base of the rose. Once the ground has frozen, you can mulch the hilled-up soil with evergreen boughs (a great way to recycle holiday trees!), shredded leaves or straw. Remember, the point of winter protection is keep frozen ground frozen, not to keep plants warm. Our region's frequent freeze-thaw cycles are much harder on plants than consistently cold weather.
You also can cover your most tender hybrid teas with rose cones. These foam covers are designed to protect roses from drying winter wind. Be sure to punch a few holes in the cone to permit some air circulation and to help cut down on disease problems under the cone. You will also have to cut the canes down hard to fit them under cones. Many rose experts recommend a final fungicide application for additional protection when using rose cones because of reduced air circulation.
Very hardy climbers and ramblers can be overwintered on their trellises with no problem. If you have chosen more tender varieties, you may need to remove the canes from the trellis and lay them on the ground, then mound soil over them. As with the hybrid tea roses, you can mulch the soil mounds after the soil has frozen.