Knock Out shrub roses have become a fast favorite of many gardeners in recent years. It is an easy-to-take-care-of rose and a very showy one, to be sure. Gardeners love the long season of bloom and the fast growth rate, which allows the gardener to plant Knock Out and have beautiful blooms in just a few months.
Knock Out is a shrub rose growing 3 or 4 feet tall and wide in a full, rounded shape. Cherry-red single blooms top the branches in clusters of a dozen or more flowers. It will bloom throughout the season, attracting butterflies, bees and hummingbirds. Since its introduction, Knock Out has become available in red Double Knock Out, pink Blushing Knock Out, Pink Double Knock Out, yellow Sunny Knock Out and Rainbow Knock Out, a single pink with yellow centers.
Grow any variety of Knock Out in full sun in moist, well-drained soil. The soil should be rich in composted manure to maximize nutrient retention, moisture retention and drainage. A regular fertilization schedule helps Knock Out perform its best, blooming from late spring to fall. Like all roses, this easy grower needs about an inch of water a week in the absence of natural rainfall.
New Knock Out bushes planted in early spring should begin growth right away and bloom at the same time as established roses -- late spring or early summer. Don't be surprised if first-year plants don't achieve full size. They are still establishing their extensive root systems for future success. Expect full growth the second year. Fall-planted Knock Outs, on the other hand, should hit the ground running the next spring and grow to full size the first season.
Maximize growth at planting by using a vitamin-rich liquid plant starter to help the roots establish. Begin fertilization two weeks after planting, using a specialized rose fertilizer according to label directions. Water during drought to keep new plants hydrated and growing. Trim established plants back to about a dozen of the freshest canes, about one foot tall, as soon the leaf buds start to open up in early spring. Begin fertilization of established plants at the first pruning.