How to Care for Knockout Roses in the Winter
Knockout roses are prized as a low-maintenance but prolifically blooming rose shrub. The Knockout produces fresh blooms as six-week intervals from spring until fall, flowering in shades of pink or red. This rose was bred to require only minimal care. Unlike some other rose varieties, Knockout roses are cold-hardy and usually survive winter unscathed. You can further ensure these rose shrubs return to their former glory each spring by taking some time in fall to prepare the roses for the cold months.
Remove dead and damaged canes from the Knockout rose plant in late fall once the bush has gone dormant. Cut the canes from the main plant at their base with pruning shears. Broken and dead canes can harbor disease organisms or pests during the winter.
Apply a winter mulch to the base of the rose bush after the ground has begun to freeze in late fall or early winter. Use dead leaves or straw mulch. Mound the mulch over the crown of the rose bush, which is where the stems emerge from the roots system at the base of the plant. Knockout roses are frost tolerant, but mulch helps prevent winter burn from freezing winds.
Prune out winter-damaged branches in late winter just before new growth begins on the Knockout bush. Shape the remaining canes with the shears into the desired final form for the rose bush.
Prune Knockout Roses In Winter
If you live in a warm climate or in zones 8 through 11, you can prune your knockout roses in the winter. One season occurs in the spring and another in the fall. Pruning mature knockouts in the winter makes sense, but get expert advice from your local nursery or extension service. Sharpen your clean pruning equipment and always cut at a 45-degree angle. Remove any thin canes or any diseased or damaged canes. If your temperature only rarely drops below freezing, you may have rose pests and eggs that do not die as they would in an area where it freezes hard. Be on the look out for insect damage and remove any canes that look questionable. Keep the roses under control. Also cut very thin canes that might be coming up from the ground. Prune mature plants by using the 1/3 rule each year in the winter. This will keep the bush vibrant.
Roses do not require winter or fall fertilization. Fertilizing too late in the year could encourage new growth on the bush that then won't survive winter.
Don't water the Knockout roses, even during brief spells of warmer winter weather. Too much water in the soil can lead to rot when the plant is dormant.