DOUBLE KNOCK OUT® – red landscape shrub rose - Radler
In a cottage-style garden where kitchen herbs meet climbing clematis, DOUBLE KNOCK OUT® settles in quickly to create a romantic yet practical backdrop of cherry-red blossoms. This compact, bushy shrub is ideal for busy households who want colour without fuss, shrugging off typical coastal rain and wind with reassuring resilience. The flowers refresh themselves with reliable self-cleaning, so You spend more time enjoying the view and less time deadheading. Planted as a low hedge, in a border or in a large 40–50 litre container, its dense foliage and continuous flowering bring instant impact, while the own-root form promises long-term stability, easy regeneration after hard pruning and a naturally extended lifespan. From an early flush of roots, through strengthening shoots, to full garden presence by the third year, it matures into an easy-care centrepiece for family outdoor life.
Usage options
| Target area |
Reasoning |
| Front-of-border cottage bed |
Compact, bushy growth keeps to a manageable 85–115 cm, giving an even ribbon of cherry-red flowers along mixed cottage borders without dominating taller perennials or shrubs, ideal for low-maintenance structure for beginners |
| Low flowering hedge beside paths or drives |
Even height and dense foliage allow a neat, colourful hedge at 60–70 cm spacing, with self-cleaning flowers that keep the line tidy with little clipping, attractive where easy everyday upkeep suits busy-owners |
| Family play garden with limited gardening time |
Outstanding disease resistance and low maintenance needs mean fewer sprays and minimal fuss, staying attractive even when life is hectic, particularly helpful for households wanting reliable colour for young-families |
| Urban front garden or small terrace |
High tolerance of heat, reflected light and intermittent drying makes it well suited to paved or street-facing plots, holding its cherry-red display even in warm, exposed spots valued by time-pressed city-gardeners |
| Large container on patio (40–50 litres minimum) |
The rounded habit and steady flowering work beautifully in generous pots, where an own-root shrub can be rejuvenated with hard pruning and fresh compost, giving long use to budget-conscious balcony-owners |
| Mixed shrub group with seasonal interest |
Its vibrant red clusters contrast well with purple or lime foliage shrubs, while equal spread and height help knit groups together, creating a cohesive, long-lived planting scheme appreciated by planning-minded homeowners |
| Lightly shaded cottage corner |
Tolerant of partial shade, it still flowers generously where sun is filtered for part of the day, enabling colour near fences or taller trees that might otherwise feel dull to traditional-style garden-lovers |
| Coastal or exposed suburban site |
Strong framework, firm anchoring roots and healthy foliage allow the plant to cope with blustery, rain-swept conditions typical of open, windswept plots, a reassuring choice for weather-aware coastal-gardeners |
Styling ideas
- Cherry-hedge – Line a front path with evenly spaced plants for a low red hedge, underplant with lavender for scent and soft edging – for homeowners wanting classic welcome.
- Teatime-border – Pair with creamy clematis and soft pink geraniums near a seating area to create a relaxed, storybook corner – for romantic cottage-garden fans.
- Kitchen-companion – Mix among herbs and leafy vegetables in raised beds, where compact shrubs add colour without stealing space – for practical kitchen-garden keepers.
- Patio-anchor – Grow one plant in a 50 litre terracotta pot with trailing thyme and bacopa for a long-season focal point – for balcony and terrace decorators.
- Colour-drift – Mass-plant in a gentle curve with smoke bush and ornamental grasses for a naturalistic, low-care sweep of red – for design-conscious family gardeners.
Technical cultivar profile
| Characteristic |
Data |
| Name and registration |
Modern shrub rose, landscape type; registered as RADtko, marketed as Double Knock Out®, part of the Knock Out® collection, ARS exhibition name Double Knock Out®. |
| Origin and breeding |
Bred by William J. Radler in the United States circa 2000, from ‘Bucbi’ seedling × ‘Razzle Dazzle’ seedling; introduced 2004 by Conard-Pyle (Star® Roses and Plants). |
| Awards and recognition |
Australian Gold Medal 2004; American Garden Rose Selections Regional Award 2018; A.R.T.S. Master Rose 2019; UC Davis WUCOLS Blue Ribbon™ water-wise distinction 2017. |
| Growth and structural characteristics |
Bushy, well-branched shrub to 85–115 cm high and wide, with moderately thorny stems and dense, slightly glossy dark purplish-green foliage providing strong garden presence. |
| Flower morphology |
Semi-double, cup-shaped clusters, 13–25 petals per bloom, medium-sized flowers (approx. 4–7 cm) borne repeatedly with abundant initial and secondary flushes through the season. |
| Colour data and phenology |
Vibrant cherry-red flowers, RHS 53C outer and 53A inner; newer blooms intense and warm-toned, ageing gradually to softer pinkish-red under strong sunlight while remaining decorative. |
| Fragrance and aroma |
Very light scent only, with a barely perceptible sweet fruity note; chosen primarily for colour impact, repeat flowering, and robustness rather than for strong fragrance effects. |
| Hip characteristics |
Rose hip production generally low; occasional small spherical hips 6–10 mm across may develop, orange-red in colour, offering modest additional autumn interest when present. |
| Resistance and winter hardiness |
Hardy to approximately −26 to −23 °C (RHS H7, USDA 5b); noted resistance to black spot, powdery mildew and rust, plus good heat and moderate drought tolerance once established. |
| Horticultural recommendations |
Suited to beds, edging, hedging, groups, parks, urban sites and large containers; plant 60–110 cm apart, allow good drainage, prune flexibly to shape and rejuvenate as required. |
DOUBLE KNOCK OUT® offers compact, bushy structure, season-long red flowering and durable own-root performance for dependable, low-effort colour in family gardens; consider it when You want lasting impact with simple care.
