Nothing could be easier than pruning Knockout roses as they are a low maintenance rose bush. Most of the roses will respond very well to an annual clean up and pruning, done in early spring just as the bud eye starts to emerge, but before active growth is present. Late winter is also an acceptable time to prune.
Start by giving the Knockout an overall pruning and grooming to give it a pleasing and attractive shape. When doing Knockout rose bush pruning, it’s good to cut down the plant by 1/3 to 1/2, to ensure optimum flower production. If your knockouts tend to grow very tall, you could actually be more aggressive when pruning, to about a foot off the ground.
After you cut the ‘Knockout’ down, remove all, but the best flower-producing canes, at the base, leaving you with 4-5 good canes. This method of pruning knockout roses will result in new canes that will grow lots of flower shoots. The end result is lots of rose flowers, which is what we all want.
You should then remove any canes growing inward, or crossing over another cane. Your goal is to open up the center of the bush for better air-circulation. Try to prune just above a bud eye. Check the drawing on this page. Don’t be afraid if you make a “wrong cut”. Rose bushes are rather tough and can take a bad pruning now and then. When you have several annual pruning experiences behind you, it will be a lot easier.
Rose Pruning Drawing Courtesy Of Vancouver’s Rose Society
Another time to do some trimming is right AFTER the first bloom flush in early summer; followed with some rose food. This is only a light trim now to cut off spent blooms and shape it a bit so it looks good. This early summer rose trimming, speeds up another great flower flush, but only if you fertilize also.
If you want your knockout roses to bloom even more, and look super good, deadheading is good idea, even though they are mostly self-cleaning.
By following these easy pruning practices, you should help maintain the health and beauty of your knock out rose.