How to Deadhead Knock Out Roses

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You can deadhead a Knock Out rose to keep it looking neat.
Image Credit: JENNIFER E. WOLF/iStock/GettyImages

Your search is over if you've been looking for a rose (​Rosa​ spp.) that doesn't require hours of maintenance to retain good looks and healthy growth. Knock Out roses (​Rosa​ 'Knock Out') are one rose species that won't be the problem child in your garden. Besides being relatively free of major pest and disease problems, it doesn't require much pruning or deadheading to continue offering its colorful display of flowers in the garden.


Knock Out Rose Noteworthy Characteristics

The first Knock Out rose was introduced to the consumer market in 2000. It was bred by William J. Radler and marketed by the Conard-Pyle company. Since then, it has become one of the most popular roses available due to its hardy nature and repeat blooming. 'Radrazz' was the original Knock Out sporting cherry-red blooms and was the winner of the All-America Rose Selections in 2000. It's developed from a cross between 'Carefree Beauty' and an unknown seedling and 'Razzle Dazzle' and an unknown seedling.

Knock Out roses have two growth patterns with the vast majority growing into bushes ranging around 4 feet tall and 4 feet wide and are hardy in USDA zones 5 through 11. However, there's a petite variety that grows to around 18 inches tall and 18 inches wide and is hardy in USDA zones 5 through 10. All produce evergreen foliage that's serrated, ranging from glossy to dull, and in colors of greens to those with tinges of purple or blue. The lightly fragranced flowers bloom almost continuously throughout the year in hues of reds, pinks, white and coral with some having yellow centers.


Deadheading and Pruning Needs

Many types of flowering plants require deadheading to promote more blooms. However, this isn't the case with Knock Out roses. The rose continues to produce a wealth of flowers regardless of whether you deadhead or not as the plant is self-cleaning. Although not necessary, you can deadhead the spent blooms for a groomed look. When deadheading the spent flowers, always use clean pruning tools so you don't transfer unwanted pests or diseases to the rose. Using hand pruners, you can simply snip the spent roses from the plant.

When it comes to other types of pruning, you should wait until the rose bush has established itself in the planting site and has grown in the location for a couple of years. If the rose requires some shaping throughout the year, only remove one-third of the growth. However, in winter or early spring, you can hard prune the plant. Cut the canes down to about 1 foot, and by the end of the season, the rose bush will have developed its full size once again.


Knock Out Rose Continued Care

The best care you can give your Knock Out rose for optimal growth is making sure it's planted in its desired conditions of full sun and in soil that drains well with a pH of 6.0 to 6.5. Select a location where the rose has room to achieve its mature size without interference so it receives good air circulation to prevents potential disease problems.

Water several times a week while the rose establishes itself. Once established, water regularly while the plant is flowering and when outdoor conditions are especially dry and hot. Using a several-inch layer of organic mulch will help the soil retain coolness and moisture and reduce unwanted growth in the area. Although not big feeders, you can apply a general-purpose blend for roses after the rose finishes a cycle of flowering. Follow the directions on the package and water it into the soil after applying.



Joyce Starr has been a professional writer and editor for over 15 years, specializing in the topics of horticulture and home improvement. For 20 years, she’s owned a garden center and landscaping/consulting business and holds numerous horticulture certificates. She’s covered numerous DIY home topics and has hundreds of articles published on gardening topics. Her work appears in SpaceCoast Living magazine, Atlanta Constitution Journal, SFGate Home Guides, 1-800-Flowers and many more.