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Archive for Sunday, April 4, 2010

Prune shrub roses to control size

Nick Krug/Journal-World Photo.Douglas County maintenance workers Jim Rousselo, left, and Brad Betts are careful as they prune a knockout rose shrub Monday, March 29, 2010 on the west side of the Douglas County Courthouse.

Nick Krug/Journal-World Photo.Douglas County maintenance workers Jim Rousselo, left, and Brad Betts are careful as they prune a knockout rose shrub Monday, March 29, 2010 on the west side of the Douglas County Courthouse.

April 4, 2010

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If your shrub roses have gotten a little bigger than you anticipated, they can easily be brought back down to size. All you need is a good pair of gloves, hand pruners, loppers and maybe a pruning saw.

The Knock Out Roses, one of the most popular varieties available, are one type of shrub rose that gets a little bigger than its tag might imply.

The Conard-Pyle Company, who produces Knock Out and its relatives says, "If unpruned, The Knock Out Family of Roses can easily grow to be more than three to four feet wide by three to four feet tall. Periodic trims will keep them maintained at a smaller size. A once a year cut (to about 12 to 18 inches above the ground) in early spring (after the last hard frost) is also recommended for maximum performance."

Twelve to 18 inches might seem a little extreme, but vigorous shrub roses should easily grow back to three to four feet tall in a single season. The shrub roses next to the Douglas County Courthouse reached more than six feet tall after being left unpruned since 2007.

Remove dead and/or diseased canes first when pruning shrub roses. Make the cut near the crown (base) of the plant. If a branch is only partially dead, prune it back to a healthy bud.

Pruning cuts should always be made to a healthy bud, a branch, or to the base of the plant. When cutting to a bud, try to cut the stem in the same angle as the bud, about a quarter-inch above. When cutting to a branch, make the cut in the same angle as the branch. Stubs (lengths of the stem left above a cut) will die back and lengthen the amount of time the plant takes to heal, but you should also avoid cutting too close and damaging the bud.

Once the dead canes are removed, take out some of the largest, oldest stems to encourage new growth in the plant. A pruning saw may be necessary to remove the largest canes from the plant's crown.

When green healthy canes remain, prune those stems back to healthy buds and branches. Cut out spindly growth and stems that cross over each other or are growing across the middle of the plant.

Although researchers recommend rinsing pruners with bleach solution when pruning some roses, the practice is usually overlooked for shrub-type roses. Hybrid tea roses, climbers, and other types are more susceptible to virus diseases that can be transferred from plant to plant during the pruning process.

If you plan to prune roses other than shrub roses this spring, determine what type of roses they are and investigate the proper pruning practices for the particular classification. Each rose type has a little different process.

Most importantly, have confidence that your shrub roses will grow back better than ever this year. Just spend a little time with them in the next few weeks.

  • Jennifer Smith is the Horticulture Extension Agent for K-State Research and Extension in Douglas County. Contact her or the Extension Master Gardener Hotline at 843-7058.

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