Rosa Double Knock Out® (Shrub Rose)

Rosa Double Knock Out® or Double Knock Out® Rose, part of the Knock Out® Roses collection, is a striking, low-maintenance shrub rose admired for its full, double cherry-red blooms contrasting dark purplish-green foliage. With excellent disease resistance, continuous flowering from spring to frost, and improved cold hardiness, this vigorous rose is ideal for borders, mass plantings, or containers, bringing bold color and elegance to any landscape.

Roses belong to the Rosaceae family, which includes other plants such as Apples (Malus domestica), Peaches (Prunus persica), and Strawberries (Fragaria × ananassa).

Description

The Double Knock Out® Rose is a well-behaved, bushy shrub that produces clusters of fully double blooms, each featuring up to 23 petals. The rich cherry-red flowers appear in flushes throughout the season and retain their vibrancy without fading. These lush blooms resemble traditional roses, offering a more refined and elegant look than the original Knock Out®.

This rose blooms abundantly from spring until frost, maintaining a near-continuous display of flowers. With its self-cleaning petals, improved winter hardiness, and strong resistance to black spot, rust, and powdery mildew, Double Knock Out® is a fantastic choice for gardeners seeking a bold, effortless rose.

Plant Type and Habit

This rose is a compact, bushy shrub with an upright, spreading habit, perfect for mixed borders, foundation plantings, and container gardens. Its dense growth and floriferous nature make it an excellent choice for adding structure and color to any garden.

Plant Size

• Height: 3–4 feet (90–120 cm)
• Width: 3–4 feet (90–120 cm)

Flowers

The Double Knock Out® Rose delivers a season-long display of rich, double blooms.

• Color: Deep cherry red
• Size: Up to 3.25 inches (8 cm) across
• Bloom Time: Continuous from spring to frost
• Fragrance: Mild, sweet, fruity scent.
• Form: Medium to large, double blooms with 23 petals, borne in small clusters

Foliage

• Type: Small, dense, leathery foliage
• Color: Deep, purplish-green, semi-glossy leaves
• Notable Features: Highly resistant to black spot, rust, and powdery mildew.

Hardiness

This Knock Out® Rose is winter-hardy in USDA Zones 5-11, making it a versatile choice for various climates. It thrives in hot, humid conditions while also being tolerant of cooler temperatures.

Wildlife Value

This rose provides valuable resources for pollinators and wildlife.

• Pollinators: Attracts bees and butterflies, and other beneficial insects.
• Wildlife Value: The dense foliage offers shelter for small birds and beneficial insects.

Uses

This versatile Knock Out® Rose is ideal for a wide range of garden applications:

• Ornamental Borders: Creates a stunning display in mixed flower beds.
• Mass Plantings: Excellent for covering large areas with color.
• Container Gardening: Thrives in pots and planters for patios and balconies.
• Hedges and Edging: Forms a colorful, low-maintenance hedge.
• Cottage and Formal Gardens: Adds structure and elegance to any design.
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Deer and Rabbit Resistance

Deer and rabbits can cause damage.

Toxicity

Knock Out® Roses are non-toxic to humans and pets, making them a safe addition to gardens.

Invasiveness

Knock Out® Roses are non-invasive and a controlled, manageable addition to gardens.

Care Guide: How to Grow and Care for Knock Out Roses

Knock-out roses are a low-maintenance, compact variety of roses ideal for gardens, borders, and containers. Their continuous blooms, vibrant colors, and disease resistance make them a popular choice for gardeners of all skill levels. Here’s how to grow and care for Knock-Out Roses.

Planting Knock-Out Roses

In Ground

• Choose a Sunny Spot: Knock-out roses need at least 6–8 hours of sunlight daily.
• Prepare the Soil: Dig a hole slightly larger than the plant’s container and loosen the soil at the bottom to improve aeration.
• Planting: Remove the plant from its container, gently loosen the roots, and place it in the hole. Ensure the base of the plant is level with the surrounding soil.
• Backfill and Mulch: Fill the hole with soil, crumble it to remove air pockets, and mulch around the base to retain moisture.
• Watering: Water thoroughly and continue watering regularly until the plant is established.

In Containers

• Select the Right Pot: Use a container with drainage holes, two sizes larger than the current pot.
• Potting Soil: Add well-draining potting soil and place the plant in the container, ensuring it sits straight.
• Fill and Water: Fill the container with soil, leaving 1–2 inches (2-5 cm) of space at the top, and water thoroughly.

Watering

Knock-out Roses thrive with deep, consistent watering. Water at the base to keep foliage dry and prevent disease. Provide 1–2 inches of water per week, increasing during hot, dry periods. Avoid overwatering—ensure well-drained soil to prevent root rot. Mulching helps retain moisture and regulate soil temperature.

Pruning

To maintain a compact size of 3–4 feet wide by 3–4 feet high, Knock Out Roses should be pruned once a year in late winter or early spring. The best time to prune is when you notice new shoots emerging from the canes—this signals that the plant is ready for its seasonal trim.

Gather Your Tools

• Gloves – To protect your hands from thorns.
• Hedge shears – For shaping the rose bush efficiently.
• Hand pruners – For precise cuts, especially when removing damaged canes.

Decide Where to Cut

The height at which you prune will determine the size of your plant at maturity. Knock Out Roses typically triple in size after pruning, so cutting them back to about 12 inches tall ensures they will reach their full 3-foot height by the end of the season.

Trim and Remove Smaller Canes

• Using hedge shears, cut back all canes to the desired height (approximately 12 inches).
• Afterward, inspect the bush and use hand pruners to remove smaller, weak, or damaged canes to improve air circulation and promote healthier growth.

Clean Up Debris

Once pruning is complete, collect and dispose of all cuttings to prevent pests and diseases from affecting your roses.

Fertilizing

Knock-out roses are low-maintenance and thrive even without fertilization. However, if you want to enhance their growth and flowering, it’s important to wait until your roses are well-established and have completed at least one full bloom cycle before applying fertilizer.

Key Fertilizing Tips for Knock-Out Roses

✅ Use the Right Fertilizer
Choose a balanced fertilizer or one specifically formulated for roses from your local garden center. Apply it after the first flush of blooms, following the manufacturer’s recommended rates and application methods.

✅ Water Before Fertilizing
Always ensure the soil is moist before applying fertilizer to prevent root burn and promote better nutrient absorption.

✅ Avoid Late-Season Fertilization
Do not fertilize in late summer or early fall, as this can encourage new growth that won’t have time to harden before the first frost, potentially leading to winter damage.

Winter Care

• In-Ground Plants: Mulch with 2–3 inches (5-7 cm) of organic matter to protect roots. Wrap the plant with burlap in areas with harsh winters.
• Containers: Bring potted Kncok-Out Roses indoors after the first frost and store in a cool, dark place.

Propagation

Knock-out Roses can be propagated for home use through various methods:

• Propagate by hardwood cuttings in autumn.
• Use softwood cuttings rooted under glass during spring or summer.
• Employ chip budding in summer for reliable growth.
• Ensure proper care and conditions for successful propagation.
• Ideal for home gardeners to expand their collection of low-maintenance roses.

Pests and Diseases

Knock-out roses are known for their excellent disease resistance, but like any plant, they can occasionally face issues from pests and diseases. Understanding common problems and how to address them can help keep your Knock-Out Roses healthy and thriving.

Pest Resistance

These roses may attract common pests such as aphids, spider mites, scale insects, or caterpillars. These pests can damage foliage, flowers, and stems, reducing the plant’s vigor.

Disease Resistance

These roses may be susceptible to several fungal diseases, including rose black spot, rust, and powdery mildew. These diseases often thrive in humid conditions, causing leaf discoloration, defoliation, or stem dieback. Disorders like rose blindness (failure to bloom) and flower balling (petals failing to open) may also occur under certain conditions. In severe cases, honey fungus, a soil-borne pathogen, can damage the plant’s root system.