} Jul 21, When to Prune. Prune Knock Out Roses in late February, recommends the University of Georgia Cooperative Extension Service. The last hard frost typically has occurred by this time, making pruning safe, according to the rose's developer, The Conard-Pyle Company. How Much to Prune. In the summer, prune rose bushes to remove dead or diseased branches. Make the cuts one inch below the diseased branch, so only healthy wood remains.
Summer is also the time to look for any branches in the center of the bush that are growing across each other. Knock Out Roses Pruning Steps: To maintain a size of 3–4’ w x 3–4’ h, Knock Out Roses should be cut back once a year to 12” high. Check your rose bush from time to time in late winter/early spring, and when you start to see new shoots growing from the canes on your rose bush, that’s a good sign that it’s time to bushdigging.clubon: 8 Federal Road, Suite 6 West Grove, PA United States.
Sep 17, Many shrub roses bloom on shoots emerging from old wood, so you can't cut back old wood in the spring without sacrificing blooms. When these plants need pruning, do so little by little.
Trim out just a few canes in the spring. And then throughout the year, prune whatever is necessary to maintain the plant's bushdigging.clubted Reading Time: 5 mins.