Double forms add diversity to Knock Out roses

Richard Bogren, Huffstickler, Kyle, Gill, Daniel J., Owings, Allen D.

Pink Double Knock Out flowers feature 18-22 petals per flower.

A Pink Double Knock Out rose plant displays blossoms to their fullest.

News Release Distributed 04/08/11

By LSU AgCenter Horticulturists Dan Gill, Kyle Huffstickler and Allen Owings

Most Louisiana gardeners are familiar with Knock Out roses. They have introduced roses to many home gardeners who otherwise never would have grown them. And they fit perfectly into a sustainable, low-maintenance landscape.

Knock Out is classified as a landscape shrub rose. This type of rose doesn’t make great cut flowers, but it will give a landscape an abundance of flowers for 75 percent of the year. They practically bloom nonstop from March to November in south Louisiana and April through October in north Louisiana. In warm winters, they may even flower in December, January and February.

Knock Out roses are less prone to blackspot disease than traditional hybrid tea, floribunda and grandiflora roses. Although they may be promoted as blackspot resistant, that’s not necessarily true. You don’t need to spray fungicides on the majority of the Knock Out roses, and the double forms have great disease resistance.

Double forms of Knock Out roses are available with pink or red flowers. Most of the Knock Out roses have single flowers with six to eight petals per flower. The double forms feature 18-22 petals per flower. This produces a pronounced visual impact when the double forms are compared with the single forms in the landscape.

The petal count and flower color are best during spring and fall blooms. Summer blooms are usually smaller with fewer petals and less intense color.

Plant these roses where you would plant other roses. They need full sun, minimum irrigation and well-prepared, well-drained landscape beds. They prefer a soil pH between 6.0-6.5. Although most gardeners plant roses in late winter through spring, Knock Out roses can be planted almost anytime of the year.

Double Knock Out and Pink Double Knock Out are advertised to grow to a height of 4-5 feet with a spread of 4-5 feet. Space individual plants 4-5 feet apart. If left unpruned, these plants can easily reach 8 feet tall.

Double Knock Out roses, like all roses, do best when pruned in mid-February and in late August to early September. A number of home gardeners, though, who are serious about their roses, lightly prune and/or remove old flowers constantly during the growing season.

Try some Double Knock Out roses in your home landscape. You’ll be amazed with the blooms and easy care for these great rose varieties.

Visit LaHouse in Baton Rouge to see sustainable landscape practices in action. The home and landscape resource center is near the intersection of Burbank Drive and Nicholson Drive (Louisiana Highway 30) in Baton Rouge, across the street from the LSU baseball stadium. For more information, go to and

Rick Bogren

4/9/2011 12:26:53 AM
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