shrub

Radtko Double Knock Out Rose

Rosa 'Radtko'

The Story

Plant Bio

Shrub roses are a broad category of hardy, easy-care roses that typically grow as bushy shrubs. The Knock Out® series revolutionized rose growing with its exceptional disease resistance and continuous blooming habit.

The Double Knock Out® Rose ('Radtko') offers the same incredible disease resistance and bloom cycle as the original, but with lush, fully double, cherry-red flowers. It is self-cleaning and blooms prolifically from spring until the first hard frost.

Uses & Benefits:

The Double Knock Out® Rose is a landscape staple, providing an incredible amount of color for very little effort. It creates a stunning visual impact when planted in masses or as a low hedge, and its long bloom season ensures the garden is never without a splash of vibrant red.

Its primary practical benefit is its low-maintenance nature. It requires no deadheading ('self-cleaning') and is highly resistant to common rose diseases like black spot and powdery mildew, making rose gardening accessible to beginners and those with little time for upkeep.

The flowers attract bees and other pollinators. While the double flowers may be slightly less accessible to pollinators than the single-flowered varieties, they still provide a valuable food source throughout the long growing season.

Essentials

At a Glance

Plant Type

Shrub

Height

42 inches

Width

42 inches

Light

Full Sun

Zones

5, 6, 7, 8, 9, 10

Water

Medium

Humidity

Adaptable

Lifespan

10-15 years

Native To

Garden hybrid

Toxicity

Non-toxic, but thorns can injure

Bloom period

Late spring – Mid-fall

In flower about 6 months of the year

Planting

How to Grow

Choose a location with at least 6-8 hours of direct sunlight per day.
Prepare a hole in well-drained, rich soil, twice as wide as the pot.
Gently remove the rose from its container and loosen the roots.
Set the plant in the hole so the graft union is at or just above soil level.
Backfill with soil, firm gently, and water thoroughly.
Apply a 2-3 inch layer of organic mulch around the base.

Pro Tip

For best performance, give them a hard prune to about 12-18 inches in early spring to encourage vigorous new growth.

Keep It Thriving

Care Guide

Do

Provide consistent water, especially during hot, dry weather.
Plant in a location with good air circulation to further prevent disease.
Prune annually in late winter/early spring for best shape and bloom.
Fertilize after the first wave of blooms to encourage reblooming.

Don't

Don't plant in a shady or waterlogged location.
Avoid overhead watering, which can encourage fungal diseases on less resistant roses.
Don't be afraid to prune it hard; it responds well.
Avoid using broad-spectrum insecticides that can harm beneficial insects.

Seasonal Care Calendar

Task	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Fertilize
Mulch
Pest Check
Prune

Watch Out For

Pests & Diseases

Common Pests

Common Diseases

In the Garden

Landscape Uses & Companions

Landscape Uses

Continuous color in mixed perennial bordersLow-maintenance hedge or mass plantingVibrant accent in large containers

Companion Plants

Nepeta 'Walker's Low'Lavandula 'Munstead'Salvia nemorosa 'Caradonna'Geranium 'Rozanne'Calamintha nepeta

Multiply

Propagation Methods

Good to Know

Common Questions

Radtko Double Knock Out Rose questions

What zones can Radtko Double Knock Out Rose grow in?

Radtko Double Knock Out Rose is hardy in USDA Zones 5–10. Inside that range it survives winter in the ground; outside it, grow it as an annual or a container plant you protect.

Is Radtko Double Knock Out Rose deer resistant?

Not reliably. Deer may browse Radtko Double Knock Out Rose, especially tender spring growth — plan on repellents or fencing where pressure is high.

When does Radtko Double Knock Out Rose bloom?

Radtko Double Knock Out Rose typically blooms in late spring through mid-fall. Exact timing shifts a week or two with your zone — Sow's bloom calendar maps it to your garden.

Does Radtko Double Knock Out Rose need full sun?

Radtko Double Knock Out Rose does best in full sun (6+ hours).

Is Radtko Double Knock Out Rose drought tolerant?

Yes — once established (usually after the first full season), Radtko Double Knock Out Rose handles dry spells with minimal watering. Water deeply its first year to build the root system that makes that possible.