Harden Off Roses
New growth on roses is the most susceptible to winter damage. To give time for all stems to become woody, stop pruning and fertilizing four to six weeks before the first fall frost. It's also a good idea to gradually reduce watering during this time, although you'll want to water plants deeply a week or so before the ground freezes hard.
Throughout summer it's important to remove any diseased or damaged foliage both on plants as well as on the ground. This fall, be sure to remove any remaining leaves that have fallen beneath the roses. As winter approaches, remove any leaves that remain on the plants. This cleanup helps to limit overwintering diseases. A dormant spray of lime-sulfur can destroy overwintering pests.
Plan for Wind
Winter winds hasten evaporation of moisture from rose canes in winter. Even if the soil is moist, the plant is unable to draw up enough moisture to replace that which is lost. The problem is especially severe when the soil is frozen. In addition to using windbreaks around rose plantings, you can spray canes with an antidessicant spray in late fall.
Overwintering Container Roses
When temperatures fall below 28 degrees F, place container-grown roses in an unheated shelter where the temperature will not go below 10 degrees F. Remove all foliage and water occasionally during the winter so the soil does not completely dry out. Bring containers back outdoors next April, and prune as needed.
Protecting Roses for Winter
To protect tender roses during winter, wait to apply protection until late fall. Prune bushes back to 2 feet. Cover with an 8- to 10-inch mound of loose soil, compost, or peat moss. To prevent peat moss from blowing away, apply a small amount of soil on top. Spray the surface with water, which will freeze and form a crust. If desired, surround the mound with a wire mesh cylinder to keep it in place. Keep the mound frozen with evergreen boughs or tree leaves.