Rosa Knock Out® (Shrub Rose)

Rosa Knock Out®, part of the Knock Out® Roses collection, is an iconic, low-maintenance shrub rose known for its vibrant cherry-red blooms, exceptional disease resistance, and prolific flowering habit. With its ability to thrive in various climates and minimal care requirements, this award-winning rose is perfect for borders, mass plantings, or containers, adding continuous color 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 Knock Out® Rose is a compact, bushy shrub that produces clusters of single to semi-double cherry-red flowers with hot pink undertones. Each bloom, up to 3.5 inches (9 cm) across, features 5 to 13 petals and retains its vibrant color even in extreme heat. The flowers appear continuously from spring until frost.

The deep purplish-green foliage provides a striking contrast to the bright blooms, and in fall, the leaves transition to rich shades of purple and burgundy, adding seasonal interest. With its outstanding resistance to black spot, drought tolerance, and self-cleaning flowers, Knock Out® remains one of the most reliable and effortless roses for gardeners of all experience levels.

This rose is the recipient of several acclaimed awards:

• 2000 All-America Rose Selection – The most prestigious rose award in the USA.
• Cary Award – Recognized for superior landscape appeal, winter hardiness, and pest resistance, particularly in New England.

Plant Type and Habit

This rose is a medium-sized, bushy shrub with a compact, rounded habit, making it ideal for mixed borders, foundation plantings, or mass landscaping. Its vigorous nature and floriferous growth ensure a dynamic presence in any garden setting.

Plant Size

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

Flowers

The Knock Out® Rose produces a profusion of showy blooms that maintain their brilliance throughout the season.

• Color: Cherry-red with hot pink undertones.
• Size: Up to 3.5 inches (9 cm) across.
• Fragrance: Mild, with subtle spice and tea notes.
• Bloom Time: Continuous from spring to frost.
• Form: Single to semi-double blooms with 5 to 13 petals per flower.

Foliage

• Type: Semi-glossy, dense foliage.
• Color: Deep purplish-green, transitioning to purple and burgundy in fall.
• Notable Features: Highly resistant to black spot, but may be susceptible to powdery mildew in certain conditions.

Hardiness

The Rainbow 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.
• Discover the Red Rose Meaning: A History of Love and Passion
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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. Drought-Tolerant Roses: The Best Low-Water Rose Bushes for Your Garden

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.