Knock Out roses are a trademarked variety of shrub rose that require relatively little care, compared with other types of roses. Unlike tea roses, Knock Out roses push the old blooms out of the way when a new bud forms, eliminating the need to deadhead. They are highly resistant to insects and disease, making them popular in gardens where roses have often failed due to chronic environmental problems.
Success with Knock Out roses begins with solid establishment. Rototill your future rose bed to at least 12 inches and incorporate lots of organic matter to ensure good drainage. Roses require lots of nitrogen and a pH of about 6.5 -- test the soil to ensure these requirements are met before planting your Knock Out roses. Planting tends to be most successful in fall or early spring, while the plant is dormant.
Keep a new Knock Out rose moist for the first month after planting to ensure it is well-established. After that, water only when the soil is dry, to a depth of about one inch. Mulch will help retain moisture between waterings. Do not irrigate with a sprinkler, since wet foliage can encourage disease.
Knock Out roses are heavy feeders, just like other roses. Apply a balanced fertilizer at a rate of 2 to 3 pounds per 100 square feet between two feedings in early spring. Apply an additional 1 to 2 pounds of balanced fertilizer per 100 square feet once buds form and continue every four weeks until mid-August.
Pruning is the most important thing you can do for a Knock Out rose. In February, remove dead wood or broken branches before shaping the bush. Open up the inside of the bush by removing unproductive interior branches. Cut back the healthy branches by one-third to one-half, but do not shear them like hedges. Selectively shape the bush by following its natural lines, leaving as much new wood as possible.
Knock Out roses require little care in winter. They are hardy from USDA Hardiness Zone 5b to 9. Where winters can be particularly harsh, mulch the plant with several inches of straw but pull the straw away from the crown as soon as the weather breaks. Your roses may suffer minimal ice damage from winter storms, but if you remove this damage during your late winter pruning, your Knock Out rose will be as good as new.
- University of California Davis: Roses: Cultural Practices and Weed Control
- Texas Agrilife Extension Service: Knock Out
- North Carolina Cooperative Extension Service: Roses for North Carolina
- University of Florida IFAS Extension: Knock Out Roses
- Univeristy of Arkansas Cooperative Extension System: Roses - Pruning
- Univeristy of Nebraska-Lincoln Extension: Pruning Roses
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