'Knock Out' Roses
The following article was written by Kristen Alexander, Union County Master Gardener Class of 2008.
The 'Knock out' Rose is a group of hybrid shrub roses bred by William Radler and sold by the Conrad Pyle Company (Star Roses). The breeder’s intention was to create a rose requiring less maintenance with greater disease resistance and cold tolerance. He combined rose varieties with noted hardiness and black spot resistance with varieties with the desired color and plant form. In 2000, the original Knock out Red was introduced and won the All American Rose Selection Award. Since this time, the rose has become a best seller.
'Knock out' Roses are compact, mounded and bushy in habit. They can grow to be 3 feet wide and 4 feet tall. They bloom every 5 to 6 weeks from late May or early June to the first hard frost. 'Knock out' Roses are self-cleaning so deadheading is not required. Pruning is recommended once every 3 years in the spring after danger of winter frost has passed. They are heat tolerant and cold tolerant to USDA Zone Five, but winter protection is recommended for the coldest areas of the country. They should be planted in a location receiving at least 4 hours of sun. They are drought tolerant, but a moist, well-drained soil is ideal.
The original 'Knock out' Rose is a red single petal landscape shrub rose. Since this variety’s inception, several other varieties have been introduced. These include the Double 'Knock out' Rose, also in red, but with full double petals that look more like a traditional rose. Other color varieties, such as the Blushing 'Knock out' Rose, have single petals in light pink. The Pink 'Knock out' Rose has single petals in bright pink while the Pink Double 'Knock Out' has double bright pink petals. The Rainbow 'Knock out' Rose has single pink petals with yellow centers. Lastly, the very fragrant Sunny 'Knock out' Rose has single petals in bright yellow that fade to a cream color.