Mortellaro's Nursery
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Rose, Knock Out®
Rosa chinensis 'Radrazz' PP#PP 11836 CPBR#0993
Knock Out Rose (Rosa chinensis 'Radrazz') is a compact, repeat-blooming shrub rose known for its low maintenance needs and disease resistance. It produces clusters of vibrant cherry-red flowers from spring through frost, providing reliable and long-lasting color in Texas landscapes. With no need for deadheading and a naturally rounded growth habit, Knock Out Roses are ideal for foundation plantings, borders, and mass plantings.
These roses perform best in full sun and well-drained soils, and they tolerate a wide range of soil types including alkaline soils common in Central Texas. Once established, they are drought-tolerant and only require moderate supplemental watering during extended dry periods. Knock Out Roses are deer-resistant and attract bees and pollinators, though their fragrance is mild compared to traditional rose varieties.
Knock Out Roses grow to a mature height of 3-5 feet with a similar spread. For mass plantings or informal hedges, space plants 3-4 feet apart. They benefit from annual pruning in late winter to encourage strong, bushy growth and to keep their form tidy.
While Knock Out Roses are generally resistant to black spot and mildew, gardeners should be aware of Rose Rosette Disease (RRD), a serious and fatal viral condition spread by microscopic mites. Although most common in North Texas, RRD has been confirmed in Central Texas as well and poses a risk wherever roses are grown. Symptoms include witch’s broom growth, excessive thorniness, and distorted blooms. There is no cure once infected, and removal of the entire plant is recommended. Additionally, in recent years, mite populations have surged during periods of drought and heat, increasing the threat of disease transmission. Monitoring and early detection are key to protecting healthy plants.
In USDA Zones 5-9, Knock Out Roses are cold-hardy, but in areas with severe freezes, mulching around the base provides added root protection. Prune back damaged stems in spring to rejuvenate the plant and stimulate fresh flowering growth.
More information on the RRD can be found :
https://apsjournals.apsnet.org/doi/10.1094/PDIS-11-22-2686-SC
https://extension.okstate.edu/fact-sheets/rose-rosette-disease.html
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Long blooming season |
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Low-maintenance rose |
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Heat & drought tolerant |
Flower Color:Red |
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Height:3-5 Feet |
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Spread:3-5 Feet |
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Spacing:3-4 feet |
USDA Hardiness Zone 5b
Available Sizes:
| Item | Description | |
| ROS-KNO-03 | #003 ROSE, KNOCK OUT |
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| ROS-KNO-07 | #007 ROSE, KNOCK OUT |
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Characteristics & Attributes
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Deer Tolerance
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Exposure
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Habit
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Soil pH Preference
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Water Needs
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Tolerates Poor Drainage
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