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 prune.
May 18, Remember that your Knock Out will make flowers 16 inches above where you make your summer cuts.
If you want continuous blooming, clip branches 16″ below the level where you want the next flush of flowers. In spring I cut mine to 18″, which is 16″ below the height I want them to flower: about waist high. It is possible to leave them higher than that, depending on how big you want the plants to.
Jan 08, Knockout roses are very fast-growing, and you have to prune them timely. A proper pruning technique is a must. February is the best month for pruning. First, remove the deadheads and any broken branches. Open up the inside of the bush by removing dead or unproductive bushclear.buzzted Reading Time: 4 mins.
Mar 01, When to Prune. The beauty of Knock Out roses is that they can be pruned nearly any time without sacrificing beautiful blooms. Here in the south, we can expect the first flush of blooms around Mother’s Day in early May. This will be the largest flush of bushclear.buzzted Reading Time: 4 mins. 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 prune. Research indicates that Knock Out roses respond best if not cut back lower that 24 inches for the hard pruning in early spring, and more moderately in the fall.
I’m surprised they have done well cut back as short as 12 inches from the ground.