Knock Out roses come in a variety of colors ranging from pink to yellow, including the deep, maroon-red original trademarked Knock Out (Rosa "Radrazz"). Knock Outs are hardy in U.S. Department of Agriculture plant hardiness zones 5 through 11, making them ideal landscape plants for Kentucky as it lies in USDA zones 6 through 7. These hardy roses don't require much care and pruning isn't required, although pruning can help you keep the size in check while tidying up your shrubs.
For regular pruning, spring is the best time of year to cut back your Knock Out rose bushes. The developers of the Knock Out family recommend using the shrub as your timeline: When you see new, tender shoots coming off your shrub, it's time to prune. You can either do regular shape-controlling pruning at this time or a massive rejuvenation pruning in which you cut your Knock Out to approximately 12 or 18 inches above the ground. For most branches, a durable set of high-quality pruning shears will do the trick. For larger branches or to cut the shrub down to 12 or 18 inches above the ground, lopping shears may be required. Sanitize your pruning shears or loppers in a full-strength solution of common household disinfecting cleaner for two to five minutes. This helps kill any bacteria, fungal or viral diseases that may be spread to your Knock Out roses from other plants.
Protecting from Cold
Kentucky has distinct seasons and, like much of the Midwest and northern part of the South, winter and spring can run together, overlap and sometimes swap weather conditions. Pruning in early spring allows for a flush of new growth for the following season, which may be harmed by a late frost or snow storm. If you happen to get one of Kentucky's late-winter cold snaps, protect your tender, newly cut Knock Out by covering it with burlap or a bed sheet.
Although Knock Out roses are self-cleaning, deadheading can make for a tidier-looking shrub. Deadheading refers to cutting off the spent blooms as they begin to wither. What's left after the blooms are spent are crumbled, browning flowers and then a bare, star-shaped sepal. To deadhead, slide your pruners down to the next leaf terminal or branch and make an angled cut, just as you would with regular pruning. You can deadhead throughout the growing season as the blooms begin to fade.
True pruning should always happen in spring, but there are times when you may need to make some additional cuts. Remove any broken or diseased branches whenever you find them, no matter what time of year. Diseases and pest infestations can sometimes be stopped by removing the infested branches or sections.