Time to discuss Knockout roses!
Published 10:36 am Monday, January 6, 2025
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“Your success and happiness lies in you. Resolve to keep happy, and your joy and you shall form an invincible host against difficulties.” – Helen Keller.
“Opportunities don’t happen, you create them.” – Chris Grosser.
“Grow old along with me! The best is yet to be.” – Robert Browning.
“The expert in anything was once a beginner.” – Helen Hayes.
Winter is here and will be around for a few weeks. Now is a good time to discuss Knockout roses and how to maintain them so that you will be better informed when rose time gets here in February.
There are six categories of roses including the hybrid teas, floribunda, grandiflora, climber/rambler, miniatures, and the bush or shrub roses. Common selections of shrub roses include the David Austin “English” roses and the Knockout roses (Rosa ‘RADrazz’) series which were created by rose breeder William Radler. Many landscapers and gardeners select roses from this group because of their prolific blooms throughout the entire growing season, as well as better disease resistance to black spot, one of the main fungal problems of roses.
Knockout roses have stunning flower power and are one of the highest demand plants to be marketed in years. It is an awesome landscape shrub rose with either single or double blossoms exhibiting disease tolerance and a long blooming cycle offering a mild, spice tea fragrance. The Knockout rose was first introduced in 2000 and acclaimed a “breakthrough shrub rose” by the All-American Rose Selections because of its exceptional disease resistance and hardiness. As their name indicates, Knockout roses offer strong curb appeal and are aesthetically pleasing.
They are drought tolerant, self-cleaning (don’t have to deadhead them), and resistant to black spot and powdery mildew. Since they require little maintenance, they are ideal for gardeners who enjoy roses but aren’t interested in the upkeep required to grow hybrid tea roses. The only limitations of Knockout roses are their lack of a strong fragrance, their short duration as cut flowers, and their susceptibility to rose rosette disease (caused by a virus).
The Knockout family of roses includes Knockout (Rosa ‘Radrazz’), Double Knockout (Rosa ‘Radtko’), Pink Knockout (Rosa ‘Radcon’), Pink Double Knockout (Rosa ‘Radtkopink’), Rainbow Knockout (Rosa ‘Radcor’), Blushing Knockout (Rosa ‘Radyod’), and Sunny Knockout (Rosa ‘Radsunny’). Also, the Knockout patio tree roses (Rosa ‘Radrazz’ and Rosa ‘Radsunny’) are available for planting in the ground or in containers. Check out the different colors of Knockout roses. The original color was red and followed by dark pink. The rainbow roses are coral with yellow centers, the blushing roses are a light to shell pink and the sunny roses are yellow. Decide if you want to plant one color or alternate colors in a desirable design pattern.
Grafted and non-grafted plants are available, and both should perform well. The Knockout family of roses can fit into any landscape. Plant them individually among shrubs, annuals and perennials in mixed beds and borders. Also, plant them in large groups to create a colorful hedge or plant them along a foundation to provide a bright border.
Like all roses, Knockout roses need to be planted in micro environments where they will receive at least six to eight hours of sunlight each day, experience good air movement and a well-drained soil with a pH between 6.0 and 6.5. They generally grow three to five feet tall and equally as wide, so be sure to space them appropriately. After planting, water them regularly until they get established. Also apply a three-inch layer of mulch to help retain moisture in the soil, pulling the mulch back from the stem of the plants. These roses are winter hardy and have good heat and humidity tolerance.
Armed with thorns or prickles, this bushy, compact, and rounded rose offers glossy, dark green foliage which turns to burgundy in the fall. Blooms are fire engine red in cool weather and a cherry red in the summer months. They are drought tolerant and adapted to periodic trims for size control or a once a year cut (to about 12-18″ above the ground) around Valentine’s Day – but not until the last hard frost has passed for maximum performance. Do not prune in the fall or the cold of winter. They can be grown in the ground or in a container which will require some winter protection.
Water thoroughly around the base of any new plantings and allow it to soak in. Repeat this procedure as necessary for the next couple of weeks to ensure good health. Mulch around the plant to help retain moisture and reduce weeds. Plant the roses about 4-5 feet apart to allow for room to grow and good air circulation. To insure continuous flowering, feed your roses with a fertilizer blended especially for Knockout roses after each bloom cycle (ie. 3% N, 4% P and 3% K with 9% Ca, 0.5% Mg and 1% S). There is no need to remove faded flowers since these roses are self-cleaning.
The Knockout rose is facing a serious viral disease called rose rosette. Once infected, a healthy plant starts producing Medusa-like bunches of new bright-red shoots. These shoots bloom, but the flowers are distorted. As rose rosette spreads through the plant, the rose gradually dies a slow death. The virus is primarily spread by tiny eriophyid mites which can be blown into landscapes with the wind. As they feed on a rose, they transmit the virus into the rose. Most rose species and their selections are vulnerable to rose rosette.
When planting new roses in the landscape, be sure to leave enough space between plants for each plant to mature without overlapping stems or leaves of neighboring roses. Remove any wild multiflora roses that exist within 100 yards of the landscape since they are very susceptible to this virus and serve to promote the problem. Unfortunately, since infected plants are not curable it is suggested to remove any diseased plants from the landscape. Enjoy your Knockout roses each season with very minimal effort.
“Now you are the body of Christ, and each one of you is a part of it.” 1 Corinthians 12:27. “Therefore, since we are receiving a kingdom that cannot be shaken, let us be thankful, and so worship God acceptably with reverence and awe, for our ‘God is a consuming fire.’” Hebrews 12:28-29. “But seek his kingdom, and these things will be given to you as well.” Luke 12:31. “There is no wisdom, no insight, no plan that can succeed against the Lord.” Proverbs 21:30. “You were taught, with regard to your former way of life, to put off your old self, which is being corrupted by its deceitful desires; to be made new in the attitude of your minds; and to put on the new self, created to be like God in true righteousness and holiness.” Ephesians 4:22-24.