Knock Out shrub roses in bloom.
image by SBJohnny/commons.wikimedia.org
Knock Out roses belong to a family of shrub roses that are bred to withstand cold and heat beyond what most roses can tolerate. At the same time they are very low maintenance, self-cleaning and disease-resistant by typical rose standards. Hardy down to USDA Zone 5, all Knock Out roses will benefit from winter cleanup and preparation. Physical protection from cold winter temperatures and winds also should be provided for Knock Outs growing in areas below Zone 7 or if temperatures in your immediate area drop below zero degrees F.
Tidy the Knock Out roses and planting beds in late fall before the first hard frost. Remove all dead foliage on the plant and any that has fallen to the ground around the base of the rose. Cut back any damaged or dying canes or branching and discard them. A clean plant and clean soil will help prevent the growth of bacteria or fungus over the winter.
Protect the roots from cold temperatures and winter drought by creating a collar around the base of the rose and filling it with an organic insulating material. Fashion a collar from folded lengths of newspaper stapled together or strips of flexible plastic garden edging. Fill in the collar with compost, disease-free potting soil or leaf mold to blanket the roots and cover the bud union.
Wrap the circumference of the plants and the collar with burlap fabric snugly holding the canes in just a bit. Wrap around each Knock Out rose at least twice and secure the burlap at the top and bottom with lengths of tied twine. Your rose will look a bit like a fat wrapped Tootsie Roll. Burlap is ideal because it will not hold condensation during warmer days, which will reduce the risk of disease.
Remove the winter protection measures in early spring after the last hard frost has passed in your region. Brush any compost or mulch that filled the collar to under the rose to feed the soil. Prune the Knock Out canes back so that there is roughly a foot to 18 inches of height from the ground. This pruning will rejuvenate the rose and prompt vigorous vegetative growth in spring and summer flowering. Make sure you complete this annual pruning only after the last hard frost.