Early May is the best time to enjoy the first blooms on modern shrub and groundcover roses in the Roanoke Valley. Two examples are plantings of red Knock Out® roses at the intersection of Williamson Rd NE & Hershberger Rd NW, which brightens this commercial area, and at the entrance planting of Brandon Oaks Retirement Community on Brandon Avenue.
The Knock Out® series of shrub roses is only one of many groups of these modern landscaping roses which grow well here in the Roanoke Valley. They bloom from spring until frost, are easy to grow, need little maintenance and exhibit good disease resistance.
Low–maintenance features mean no deadheading or extensive pruning. Spent blooms either drop off or develop into attractive rose hips which may remain on the bush during the winter. Prune in early spring to 12– to 18–inches above the ground to maintain bushes at attractive heights. When left unpruned, bushes can easily grow to be more than 3-4′ wide x 3-4′ tall. Of course, prune at any time to remove dead or diseased branches.
Disease resistance does not necessarily mean disease proof. These roses are black spot resistant except in the deep south. They remain powdery mildew resistant except under the most difficult conditions of high humidity and moist conditions. Knock Out® roses appear to be resistant to Japansese beetles.
Knock Out® roses are easy to grow when they are planted in suitable rose growing conditions. Bushes need:
- Good air circulation and full sunshine for a minimum of 6 hours each day.
- Soils that are moist but well draining, high in organic matter and fertility, with an average pH between 5.5 and 6.5.
- Mulch to about one to two inches to conserve soil moisture and to keep soil cool when soil is damp. Test soil every year or so because organic mulches may alter the soil pH by increasing acidity; additional nitrogen may also be needed.
- Water with soaker or drip irrigation when needed to a depth of about one foot. Overhead watering especially in late afternoon or evening encourages disease growth.
- Fertilize on a regular schedule. Horticulturalists at the Lewis Ginter Botanical Garden (Richmond, VA) advise monthly feeding with Espoma Rose-tone® 4-3-2 “bloom booster” fertilizer such as 20-20-20 diluted in water.
Bill Radler, Wisconsin-based rose breeder, created this revolutionary series of shrub roses. The bright red-flowered Knock Out® Rose was Radler’s first commercial success and a 2000 AARS winner. It broke all records for sales of a new rose and is the most widely sold rose in North America.
Conard-Pyle Co./Star® Roses, a PA-based wholesale container nursery, introduced all seven members of the Knock Out® family of roses:
- The Knock Out® Rose – The original single red-flowered rose developed by Radler.
- The Double Knock Out® Rose – Fully double red flowers look just like a classic rose.
- The Pink Knock Out® Rose – Single bright pink flowers.
- The Pink Double Knock Out® Rose – Double bright bubble gum pink flowers that are stable and unaffected by heat.
- The Rainbow Knock Out® Rose – Coral pink blooms with yellow centers; 2007 AARS winner.
- The Blushing Knock Out® Rose – Light pink single blooms that, with age, fade to a delicate pink.
- The Sunny Knock Out® Rose – The only fragrant member in the Knock Out® family of roses with bright yellow single flowers that fade with hot temperatures to a pastel cream color.
The Knock Out® family of roses are available in the Roanoke area at:
5881 Starkey Road, 24014