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Rosa chinensis ''Radtko''
Rose, Double Knock Out
- Long blooming season
- Low-maintenance rose
- Heat & drought tolerant
- Category: Trees & Shrubs, Discontinued
- Patent: 16202
- Hardiness Zone: 6b
- Height: 3-5 Feet
- Spread: 3-5 Feet
- Spacing: 3-4 feet
- Bloom Color: Pink, Red
Double Knock Out Rose (Rosa chinensis 'Radtko') is a double-blooming variety of the original Knock Out Rose, offering fuller, more lush flowers with the same easy-care appeal. It produces deep cherry-red double blooms that resemble traditional roses but without the high maintenance. Blooming from spring until frost, Double Knock Out brings extended color and form to borders, hedges, and foundation plantings.
Like its single-bloom counterpart, this rose thrives in full sun and well-drained soil, performing well in both alkaline and slightly acidic soils. It is drought-tolerant once established and deer-resistant, making it suitable for low-maintenance gardens throughout Central and North Texas. The dense foliage and consistent flowering habit make it a strong performer in both mass plantings and individual landscape accents.
Double Knock Out grows to a mature size of 3-5 feet tall and wide. When planting in rows or masses, space plants 3-4 feet apart to allow air circulation and full shape development. Regular pruning in late winter encourages compact growth and heavy flowering. The plant rarely requires deadheading, though trimming spent blooms can improve its appearance.
Gardeners should monitor for Rose Rosette Disease (RRD), which is caused by a virus spread by microscopic eriophyid mites. While RRD is most prevalent in North Texas, it has been confirmed in Central Texas as well. Symptoms include abnormal growth, excessive thorns, and distorted buds. The disease is fatal, and affected plants must be removed. In recent years, mite populations have increased during drought and high heat, so it’s critical to inspect roses regularly during the hottest months and practice good sanitation.
In USDA Zones 5-9, Double Knock Out Roses are cold-hardy, but in colder areas of Texas, mulching in winter protects the roots from deep freezes. In spring, pruning away any damaged wood helps the plant rebound vigorously for another season of blooms.
Links about Rose Rosette Disease :
https://extension.okstate.edu/fact-sheets/rose-rosette-disease.html
https://apsjournals.apsnet.org/doi/10.1094/PDIS-11-22-2686-SC