When to Prune Knock Out Rosebushes

Description

• Knock Out is a shrub rose growing to a loose, global 3 feet tall and 3 feet wide. It bears single, cherry rose blooms in clusters. Knock Out is favored for its disease resistance, being almost immune to black spot, probably the rose world's most infamous fungus. Because of its round, compact form, Knock Out is often planted as foundation plants or hedges.

Spring Pruning

• Plants should be pruned in early spring when the leaf buds start to open up -- usually within two weeks before or after St. Patrick's Day. Prune back the bushes to the dozen strongest canes. Cut to about 12 inches and leave a vase-shaped frame with canes radiating from the center. Cut the canes 1/4 inch above an outward facing bud to direct the new growth in the right direction.

Summer Pruning

• Knock Out is a repeat bloomer and summer pruning helps it bloom its best throughout the season. After the first flush of blooms is past, cut off the top 6 to 12 inches of each cane. This removes spent flower structures and encourages fresh growth. Repeat this a few times throughout summer. Each blooming cycle lasts about six weeks. The last pruning should be about Labor Day to allow the plants to slow down and the canes to toughen up in preparation for winter.

Tips

• If you would like to reduce the size of your plant in summer, don't be afraid to cut it back hard. Many gardeners use hedging shears in summer to trim large plantings of shrub roses. Maximize the benefits of pruning by fertilizing your Knock Outs each time you prune in spring and summer. It is always appropriate cut out dead and diseased plant parts. There is no need to prune any rose in preparation for winter unless there are long or stray branches that might whip in the wind and injure passersby.