Rosa, Genus, 'Radrazz', Cultivar,
- Genus
- Cultivar
Knockout Rose
Garden hybrid (bred by William Radler, USA; introduced 2000)
Overview
Rosa 'Radrazz' (trade name Knock Out) is a deciduous shrub rose growing 36-60 inches (90-150 cm / 3-5 feet) tall and wide. Cherry-red to deep pink-red single to semi-double flowers 3-3.5 inches (7-9 cm) in clusters continuously from June through frost — an 18-20+ week bloom season. Self-cleaning: spent petals drop without deadheading. Glossy dark green to purplish-bronze disease-resistant foliage turning gold in fall. In the rose family (Rosaceae). Bred by William Radler (Wisconsin, USA), introduced in 2000. The registered cultivar name is 'Radrazz'; the trade name is Knock Out. AARS 2000 (All-America Rose Selections). The top-selling rose in North America. Disease-resistant: bred for immunity to black spot (Diplocarpon rosae) — fungicide spraying is not required. Lightly fragrant (tea-rose scent). Flowers on new wood (current-season growth) — prune in early spring. Not deer-resistant — deer browse rose foliage and flowers. Rose rosette disease (RRD, transmitted by eriophyid mites) is the primary threat — no cure; infected plants must be removed and destroyed. Tolerates clay soil. Small orange-red hips form in fall but do not inhibit flowering. Drought-tolerant once established. Full sun (6+ hours). Non-toxic. Zones 5-9. Growth rate is fast.
Native Range
Garden hybrid — bred by William Radler in Wisconsin, USA. Introduced 2000. The genus Rosa contains over 300 species, native to the Northern Hemisphere.Suggested Uses
Commonly planted in borders, hedging, mass plantings, and containers of at least 5 gallons (19 L) in zones 5-9. Continuous bloom June-frost without deadheading or spraying. Tolerates clay. The top-selling rose in North America. Not deer-resistant. Rose rosette disease risk. Non-toxic.How to Identify
Appearance
Size & Dimensions
Height3' - 5'
Width/Spread3' - 5'
Bloom Information
Detailed Descriptions
Flower Description
Cherry-red to deep pink-red, single to semi-double, 3-3.5 inches (7-9 cm), in clusters; self-cleaning; continuous June through frostFoliage Description
Glossy dark green to purplish-bronze, disease-resistant; turning gold in fallGrowing Conditions
Sun Requirements
Requires 6-10 hours of direct sunlight daily
• Full Sun: 6+ hours of direct sunlight
• Partial Shade: 3-6 hours of direct sunlight
• Full Shade: Less than 3 hours of direct sunlight
Care & Maintenance
Care Guide
Full sun (6+ hours). Tolerates clay. Flowers on new wood — prune in early spring. Disease-resistant (black spot immune — no spraying). Self-cleaning (no deadheading). Rose rosette disease is the primary threat — remove and destroy infected plants. Not deer-resistant. Non-toxic. Zones 5-9.Pruning
Prune in early spring (February-March) — cut back by one-third to one-half. Flowers on new wood. Remove dead and crossing canes. Can be sheared with hedge trimmers for mass plantings. Rose rosette disease: remove and destroy infected plants immediately.Pruning Schedule
Prune: February–March
early spring
Container Growing
Suitable for container growing
Minimum container size: 5 gallons
