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 in early spring (after the last hard frost of the year). In general, if you cut your Knock Out® Rose back in early spring, it will triple in size by the end of the season (cutting back to 12” high should yield a plant that is about 3’ tall by the end of the season).
Follow these simple steps to prune your Knock Out® Roses:
STEP 1: Decide When to Prune
Prune your rose bush in early spring, never in the fall and never in the winter. Check your rose bush from time to time as spring moves along and when you start to see new shoots growing from the canes on your rose bush, that’s a good sign that it is time to prune.
STEP 2: Use Proper the Tools
You will need a few basic tools when the time comes to prune your roses: gloves, lopping shears, small hand shears, and a pair of hedge trimmers.
STEP 3: Determine How High to Prune
Determining how high you want to prune depends on how high you want your rose bush to finish. Your rose bush will usually triple in size after pruning so cutting it back to about a foot will leave it at 3 feet when it finished growing.