I get a lot of questions about taking care of Knock Out Roses at this time of year with people unsure of what to do with those vigorous Knock Out Roses that they are sure will be engulfing their yards soon! You really need to hack them back to stubs and people are scared to do this. You cannot kill a Knock Out Rose! These shrubs are tough and can take lots of abuse.
The natural inclination of The Knock Out® Family of Roses is to grow to about 3′ wide x 4′ tall, but they are easily maintained at a smaller size through pruning, and that means severe pruning!. They are ideal for growing in mixed borders, in containers or as a hedge. A hedge of Knock Outs is beautiful! Think of using these instead of Forsythia for a colorful hedging plant that will give you months of blooms.
Just like other roses, The Knock Out® Family of Roses perform best when planted in full sun. The soil should be well drained and fertile. In partial shade, they will not bloom as profusely and can get leggy looking.
Plant the roses 4 feet apart to allow for room to grow and good air circulation.
To keep the flowers coming, feed your roses with a fertilizer blended especially for roses. This should be done after each bloom cycle. There is no need to remove faded flowers because these roses are self-cleaning – another task you can remove from your to do list!
Prune in late winter or early spring, while the plant is still dormant. Remove any dead or damaged wood, do a little shaping if necessary, and take out some of the interior stems to improve air circulation. Every 2 or 3 years remove about one-third of the old branches to stimulate new, fresh growth. If you are trying to keep the roses at a certain height, you can cut them back hard with hedge shears. No need to worry about the usual rose pruning rule of cutting back to an outward facing leaf bud – just lop them down to the desired size. I’ve even seen Knock Out® Roses spring back beautifully after being cut down to 6-inches.