KNOCK OUT® – cherry-red landscape shrub rose - Radler
Imagine your front garden after rain: glistening paving, clean air, and a low-care rose carrying bright, cherry-red colour from spring to frost. KNOCK OUT® settles quickly into small London plots and tough suburban soils, coping calmly with blustery showers and heavier clay by simply asking for decent drainage and occasional attention. Its bushy shape and self-cleaning blooms keep borders neat without deadheading marathons, while semi-double, open-centred flowers invite visiting bees to an accessible pollen feast. As an own-root shrub it builds its strength steadily – roots in the first year, rising shoots in the second, and full, reliable ornamental impact from the third – giving a long-lived backbone for sustainable, rainwater-friendly gardens and relaxed urban owners.
Usage options
| Target area |
Reasoning |
| Small front garden focal shrub |
KNOCK OUT® forms a dense, bushy mound around 90–120 cm high and wide, giving an instant sense of structure without overwhelming a narrow London front. Its reliable framework matures steadily on its own roots for long-term balance in compact spaces, particularly for the busy homeowner. |
| Low-maintenance flowering hedge |
Planted at about 55 cm intervals, it builds a cherry-red, self-cleaning hedge that rarely needs more than a light annual trim. Disease resistance to black spot, mildew and rust keeps the line green and healthy, even under higher humidity, suiting the time-poor gardener. |
| Easy-care mixed border backbone |
Its long season of semi-double blooms and dense, mid-green foliage anchor mixed borders with minimal feeding or pruning. Good heat and short-drought tolerance mean it continues performing between showers, particularly when combined with mulching for the eco-conscious planter. |
| Rainwater-friendly urban planting |
With good resilience to rain and wind, this shrub thrives near permeable drives or gravel strips where excess water is channelled into planting pockets rather than drains, supporting practical rain capture for the sustainability-minded owner. |
| Pollinator-friendly family garden bed |
Semi-double, open-centred flowers expose pollen clearly, attracting bees and other beneficial insects across repeated flushes. Children can watch pollinators at work in a safe, compact shrub that still reads as “girly” and colourful for the wildlife-curious family. |
| Containers and large patio tubs |
In a 40–50 litre or larger container with peat-free compost, it provides season-long colour on balconies or paved terraces, needing only basic watering and an annual feed. Strong own-root growth copes well with urban microclimates for the balcony gardener. |
| Resilient coastal or exposed sites |
Compact habit and strong, healthy foliage allow it to stand up to blustery winds and driving rain without constant spraying. Its proven disease resistance keeps leaves presentable where fungal pressure is higher, reassuring the practical coastal gardener. |
| Long-lived, low-input landscape groups |
Planted in groups at 65 cm spacing, it fills beds quickly, maintaining ornamental value year after year with minimal renewal. Own-root plants recover well from accidental damage or harsh pruning, reducing replacement costs for the budget-aware planner. |
Styling ideas
- Cherry-Pathway – Line a short front path with KNOCK OUT® and soft sweet alyssum for a scented, bee-pleasing entrance that still feels orderly – ideal for small-plot city dwellers.
- Soft-Contrast – Combine the cherry-red flowers with the silvery foliage of Artemisia schmidtiana ‘Nana’ to soften hard paving and gravel – perfect for design-conscious terrace owners.
- Evergreen-Frame – Use a backdrop of compact cherry laurel behind a KNOCK OUT® hedge to keep winter structure while summer flowers steal the show – suited to year-round busy families.
- Herbal-Companion – Interplant with lavender, sage or nepeta to echo the easy-care, drought-tolerant style and support more pollinators – attractive for low-input, eco-friendly gardeners.
- Pink-Play – Pair KNOCK OUT® with blush perennials and pastel annuals in a “girly” front border that stays tidy thanks to self-cleaning flowers – appealing to colour-loving beginners.
Technical cultivar profile
| Attribute |
Data |
| Name and registration |
Modern shrub (landscape) rose, registered as RADrazz; marketed as KNOCK OUT®. ARS approved exhibition name Knock Out®, collection Knock Out®, commercial bed and landscape shrub type. |
| Origin and breeding |
Raised by William J. Radler in the USA from ‘Carefree Beauty’ × ‘Razzle Dazzle’; bred 1988, registered 1999, introduced 2000 via Conard-Pyle / Star Roses in North America. |
| Awards and recognition |
AARS winner 2000, ADR Germany 2002, Portland Gold Medal 2003; World Federation of Rose Societies Hall of Fame 2018, widely regarded as a benchmark easy-care shrub rose. |
| Growth and structural characteristics |
Bushy, compact shrub typically 90–120 cm high and wide with dense, mid-green, slightly glossy foliage (RHS 136A) and moderate prickles; naturally rounded, ideal for mass planting or hedging. |
| Flower morphology |
Semi-double, cup-shaped blooms with about 13–25 petals, borne in clusters. Large-flowered (approx. 7–10 cm), remontant with generous repeat flushes and good self-cleaning of spent flowers. |
| Colour data and phenology |
Cherry-red flowers; RHS 53B outer, 53C inner petals. Bright cherry-red in bud, medium cherry red at full bloom, fading lighter in strong sun yet remaining vivid and slightly deeper in cooler weather. |
| Fragrance and aroma |
Fragrance is very weak and often barely noticeable; grown primarily for continuous colour, health and ease rather than scent, making it suitable where strong perfume is not desired. |
| Hip characteristics |
Rose-hips rarely develop due to strong self-cleaning; where present they are small, spherical, orange-red hips around 7–11 mm diameter, generally of minor ornamental significance. |
| Resistance and winter hardiness |
Excellent resistance to black spot, powdery mildew and rust, with clean foliage in typical UK conditions. Fully hardy to about −29 to −32 °C (RHS H7, Swedish zone 5, USDA 4b) for reliable overwintering. |
| Horticultural recommendations |
Best at 55–65 cm spacing in beds or hedges, up to 100 cm as a specimen. Thrives in full sun or light shade with low feeding and minimal pruning; water during prolonged droughts, especially in containers. |
KNOCK OUT® offers long-season cherry-red colour, robust health and dependable own-root longevity with minimal care, making it a considered choice for sustainable, low-fuss gardens.
