Knock Out roses are a very popular variety of landscape rose being used in residential as well as commercial landscapes. Capable of growing into large, 4-foot-tall shrubs, Knockout roses produce large numbers of blooms throughout the spring and summer months. As with any landscape shrub, pruning is essential to maintain the health and size of the plant in relationship to the landscape and surrounding area. Take the time during the winter and spring to properly trim and train your Knock Out roses
Perform most of the aggressive pruning to your Knock Out rose bush in the winter. Use a pair of bypass hand pruners to cut back long shoots that could be damaged or broken by wind, snow or ice. Cut the Knock Out rosebush back to between 12 and 15 inches.
Select a shoot that you would like to cut and locate a junction point where a smaller limb grows from the main shoot. Place the pruners just above the junction with the blade of the pruners on the lower side. This will help produce a clean, smooth cut.
Squeeze the handles of the pruners and cut the shoot through completely. Continue working around the Knock Out rosebush repeating the process with other longer shoots.
Examine the overall shape of the Knock Out bush and remove any shoots that are skewed to the side. Also remove any closely growing shoots that may be in competition for space.
Prune the rose one again in the spring following the initial new growth. This time only lightly shape the rose to help maintain the overall shape with the landscape.
Cut or pinch expired blooms from the rose to help make room for new buds. This should be done throughout the blooming season to prolong bloom production.