Knock Out roses rebloom every 5 to 6 weeks until frost.
image by Ryan Somma/ Flickr Creative Commons
The Knock Out rose, bred by William Radler, is actually a group of shrub roses specifically bred to be low maintenance, disease-resistant and cold-hardy. In 2000, the original red Knock Out rose received the All American Rose Selection Award and soon became a best-selling rose in the US. These mounded rose bushes spread to 3 feet and reach heights of 4 feet, blooming repeatedly from spring until frost. Cold hardy to zones 5, these hardy roses provide a profusion of rich color throughout the summer. With winter protection, they may survive in colder climates.
Prune Knock Out roses lightly in late fall to maintain overall shape of the bush. Cutting back is not recommended at this time. Wait until after the last hard frost of spring to cut back overgrown bushes to 6 to 8 inches, if desired. This promotes lush green foliage and dense growth.
Remove leaves after a killing frost and clean any plant debris from the surrounding area. Trim away dead or diseased branches. Tie canes upright with garden rope to prevent breakage and damage from cold winter winds.
Mound loose soil around the base of the bush to a depth of 6 to 8 inches. This protects tender roots from the damaging effects of freezing and thawing soil.
Create a cylinder from chicken wire or hardware cloth that fits around the bush leaving 3-5 inches of space between the canes and the inside of the cylinder. The cylinder should be three to four inches taller than the tallest canes. Anchor the cylinder in the soil with spikes or wooden stakes.
Fill the gap between the Knock Out rose bush and the wire cage with straw or leaves. Cover the top of the bush with 3-4 inches of mulch.
Wrap the cage with burlap and secure with garden rope. This provides insulation against sharp winter winds and prevents damage from repeated freezing and thawing that may occur during the winter.