Q. How soon should I prune my Knock Out roses this spring?
Jenny from Youngstown
A. Most roses are finicky when it comes to care throughout the year. Many types of roses need extra protection through the winter and can be heavily damaged during our winters here in the Mahoning Valley.
Knock Out roses are generally easy to care for throughout the year. They don’t need the extra winter protection. They are less susceptible to the black spot disease that plagues many roses during our hot, humid summers.
When it comes to pruning, Knock Outs are treated somewhat the same as other roses. The big difference is many other roses are pruned with an open center to increase air circulation, resulting in reduced disease pressure. This is not necessary with Knock Out roses planted in full sun. Those planted in partial shade may be pruned to an open center, though, if disease pressure is seen. I have seen black spot pressure on yellow Knock Out roses.
Wait a couple of weeks until you see the forsythia bloom before starting to prune any roses. Always start with a clean, sharp pair of pruners. Begin with anvil pruners to cut out the completely dead canes (bypass pruners could be bent or damaged by the stiffness of dead canes).
Then, move on to bypass pruners to make precise, clean cuts on canes which show life, but have dark brown patches from winter damage. Cut just below the damaged part of the cane. Be sure to cut at a 45 degree angle, and about º inch above a bud.
Reduce the remaining canes to about 12-18 inches high. This will encourage growth, where you will see the first blooms of the season. If you have lots of canes left, you’ll need to decide which ones are best. You only need five or so canes when you are done pruning to have a vigorous plant to start spring.
From year to year, you’ll get better at pruning these roses. Knock Outs can be pruned rather harshly compared to other roses, and will still produce well throughout the season.
For more information see: http://go.osu.edu/roseprune.
Eric Barrett is OSU Ext. educator for agriculture and natural resources in Mahoning County. Call the office hotline at 330-533-5538 from 9 a.m. to noon Mondays and Thursdays to submit your questions.