The Knock Out is one of the best-selling roses in North America. Knock Out Roses are known for their low-maintenance growth, their cold and heat tolerance and their resistance to disease. These beautiful roses will flower every five to six weeks for five to seven months. In 2000 the original Knock Out variety was given the All-American Rose Selection Award.
The Knock Out Rose was created by William Radler, a lifelong rose breeder. After obtaining his first rose at age 9, he quickly became an experienced rose grower. Eventually he decided to work on creating a rose that did not require the extensive maintenance demanded by most varieties. He combined many varieties, including Faberge, Playboy, Razzle Dazzle, Deep Purple, Applejack, Eddie's Crimson and Tampico, eventually producing a single seed from a father and mother plant. That seed grew to become the first Knock Out Rose, which is now sold by the Conrad-Pyle Co.
One of the biggest problems with many rose varieties is their susceptibility to disease. The Knock Out Rose was specially bred to create a high level of tolerance to many diseases, especially black spot. It is also resistant to powdery mildew--another common fungal disease--and to aphids.
The Knock Out Rose was bred in USDA Zone 5, where winter temperatures can go below -10 F. According to Texas A&M University, the rose is also hardy to Zone 4, where temperatures can descend to -20 F. Knock Out Roses are also tolerant of heat and drought. The rose will continue to produce flowers well into the fall and will only stop when the first hard frost arrives.
Care & Maintenance
Knock Out Roses were bred to require relatively little care, and they live up to that ideal. The rose requires only a light pruning in spring. Hedge trimmers should be used to cut the plant down to half or one-third of its height. Deadheading is unnecessary; the plant is self-cleaning. Pesticides are usually unnecessary as well.
Knock Out Roses are available in seven varieties as of August 2010. Two versions boast double-type blooms: the Pink Knock Out and Double Knock Out varieties. There are also versions with more basic flower shapes in a number of colors, including yellow-white, light pink, and darker pink with yellow centers. Of these, the yellow-white type, called the Sunny Knock Out, is the only one with a strong fragrance.