Knock Out roses are shrub roses that bloom all summer long. Although their roses lack a strong fragrance they do provide a nice long season of color in many gardens. Also, Knock Out roses are very resistant to many types of rose diseases, like black spot and powdery mildew, and they are tolerant to drought and require very little upkeep. However, like all roses, Knock Out roses need to be trimmed to keep them in line.
Remove any dead, diseased or damaged wood in the early spring. Cut it back to the nearest healthy bud on the Knock Out roses. Make the cut with the pruning shears at a 45-degree angle. If no part of the cane is living, cut the cane at the base of the Knock Out rose bush.
Remove the oldest canes in the early spring. Old canes are the thickest, usually an inch or more in circumference. Cut them back with the pruning shears to the base of the Knock Out rose bushes to promote new growth.
Shape the Knock Out roses in the spring to your desired shape. Do not remove more than one-third of their height.
Trim back Knock Out roses during their growing season as needed. Cut back canes that are growing over their bounds.