Rosa 'Radrazz'
flowerThe Knock Out rose (Rosa 'Radrazz'), introduced in 2000, revolutionized rose growing by being almost foolproof. It is a rounded, bushy shrub rose, typically 3 to 4 ft, that produces flushes of cherry-red, lightly scented single flowers continuously from spring until frost. Crucially, it is self-cleaning (it drops spent blooms and reblooms without deadheading) and was bred for outstanding resistance to black spot and other diseases that plague traditional roses, so it needs no spraying. Cold hardy to about zone 5 and extremely heat- and drought-tolerant once established, it gives the look of a rose garden with a fraction of the fuss.
Sun
full sun
Water
Every 5 days
Bloom
~45 days
Difficulty
easy
Lifecycle
perennial
Comes back every year
Spacing
3-4 ft apart
Planting Depth
Crown/graft at or just below soil line
Soil pH
6.0-6.5
Soil Type
Rich, well-draining loam
Hardiness Zones
Zones 5 – 10
When to Fertilize
Spring and after the first bloom flush
Fertilizer
Balanced rose fertilizer or compost
Plant Knock Out roses in full sun (at least 6 hours) in rich, well-drained loam, spacing shrubs 3 to 4 ft apart for airflow. Water deeply and regularly the first season to establish, then it is quite drought-tolerant. It needs no deadheading to rebloom, but a hard prune in late winter or early spring, cutting the shrub back by about a third to a half, keeps it shapely and vigorous and triggers strong new flowering wood. Feed in spring and after the first big flush. It is genuinely low-maintenance: no spraying program is needed thanks to its disease resistance, though good airflow and clean-up still help.
🌼 Have a different variety?Cultivars of the same species usually share the same basic care — they differ mainly in flower color, height, and bloom form, not in how you grow them. So this guide still applies even if your exact variety isn't the one shown.
Direct sow
Apr 15
Projected first bloom
May 30
Good neighbors that attract beneficial insects or deter pests
Proactive ways to stop trouble before it starts — tap a name with an arrow for its full guide
The most serious threat to Knock Out roses - an incurable mite-spread virus causing witches-broom, excessive thorns, and distorted red growth; there is no cure, so remove and destroy infected plants promptly and avoid crowding
Skeletonize leaves and chew blooms in summer - hand-pick into soapy water in the cool morning and avoid pheromone traps that attract more
Cluster on new growth and buds - hose them off and rely on ladybugs and lacewings
Knock Out is highly resistant, but in wet climates still water at the base, give airflow, and clean up fallen leaves
Knock Out roses are bred for landscape color rather than long-stemmed cutting, but the flushes of bloom make cheerful short-stemmed posies - cut in the cool morning just as buds open, into clean water. The big advantage is that no deadheading is required: the shrub is self-cleaning and reblooms on its own. The one pruning task that matters is the hard cut-back in late winter, which rejuvenates the plant and fuels the season of bloom. Wear gloves, as the canes have thorns.
Unlike packed double roses, the more open single-to-semi-double Knock Out blooms give bees reasonable access to pollen, so it has modest pollinator value alongside its main role as a long-blooming ornamental shrub. It produces few hips because it keeps reblooming rather than setting seed. Its real contribution is months of dependable color with no spraying, making rose-like beauty accessible to beginning gardeners.
For educational and informational purposes only — HomeSown is not medical, health, or other professional advice. Always positively identify any plant before handling or eating it; some plants, and some parts of otherwise-edible plants, are toxic. Consult a qualified professional before consuming or otherwise using any plant, especially if you are pregnant, nursing, taking medication, or have a health condition.