'Knock Out' was developed by amateur rose breeder William Radler in his Milwaukee, Wisconsin basement in 1989.

The cultivar was developed from a cross between two unpatented, unnamed seedlings bred by Radler himself.

The pollen parent, code RAD84-196.8, had as parentage Razzle Dazzle x [Deep purple x (Fabergé x Eddie's Crimson)] Compared to the other new hybrid rose plants in his backyard test garden that year, Radler recalled that new cultivar was exceptional.

It is a landscaping or shrub rose in the Floribunda style, but totally disease-free, drought-tolerant, extremely hardy and amazingly floriferous."

[3] Flowers open from attractive buds, and are a bright cherry red with a white center and green-yellow stamens.