Not only are Knock Out Roses among the most disease-free roses in the world, they are easy to care for in every other way. Pruning Knock Out Roses is not absolutely necessary, but in our experience they benefit from it and it's very easy to do!
Here are some guidelines for pruning Knock Out Roses the right way...
How To Prune Knock Out Roses
Late Winter Pruning
Knock Out Roses can be pruned heavily in late winter or very early spring. This pruning ensures plants will have a good habit and even more healthy blooms throughout the season. This hard pruning can be done while plants are still dormant in later winter or just when you begin to see new leaves begin to emerge. At this time, cut the shrub back to about 12-18" above the ground.
When pruning, make your cut just above an outward-facing leaf bud. The leaf bud is not the thorn but a small protrusion from which will grow a new leaf or branch. We've found that pruning just above an outward-facing bud will promote a wider, bushier rose bush.
Summer Pruning
Knock Out Roses can be pruned lightly throughout the active growth season. Deadheading spent blooms or clusters will encourage quicker formation of new buds and rebloom. Knock Out Roses usually have several bloom cycles throughout the growing season. After each cycle simply snip off spent blooms or clusters at the base of their stem or down to a point an inch or so above the first five leaflet leaf. A five leaflet leaf set tends to be where the cane is thick enough to support the next long stem bloom that will grow from it. For shaping purposes, you can also cut back stray branches that are spoiling the shape of the bush. Damaged branches can and should be removed any time of year.
Cease pruning about 45 to 60 days before the average first frost date in your area.
That's about it. See, that was easy!