Knockout roses are a new variety designed to be disease-resistant and easy to care for. They were developed by botanist and rose expert William Radler. Unlike many other roses, Knockout roses are not designed to be used as cut flowers. They were designed specifically for outdoor landscapes and are easy enough to care for that even the most inexperienced rose grower can be successful. Introduced in 2000, they have rapidly become one of the most popular landscape roses.
In addition to being disease-resistant, Knockout roses are also "self-cleaning" which means there is no need to deadhead them to keep them blooming. They bloom in five- to six-week cycles and require very little care. They will take up a space about 3' by 3', in a rounded shape that requires little pruning. The blossoms are about 3 inches across, bright red, and bloom clear through the summer and well into fall.
Like all roses, Knockout roses need bright sunlight although they can tolerate some shade. They are heat-resistant so you can plant them in sunny hot locations. Plant them in well-drained, fertile soil. Because they tend to be somewhat unattractive in the winter, give them a backdrop of evergreens for camouflage.
As with other roses, water only at the base and avoid getting the leaves wet to prevent fungus problems. They are rated for USDA zones 5 and south, so a layer of mulch in the winter will protect the roots. Place the mulch after the first frost. If your Knockouts are planted in pots, take them indoors to overwinter.
Prune your Knockout roses in the early spring. If your winters are mild, prune them to 12 to 18 inches above the ground. If your winters are harsh, you can remove all the dead canes and prune to three inches. Prune throughout the growing season to keep them the size and shape desired.
Feed with granular rose food in the spring and then fertilize throughout the blooming season with foliar feedings by spraying liquid fertilizer directly on the leaves.