How to Grow and Care for Knock Out Roses—the Easiest Rose Type a Gardener Can Plant

Whether you’re an avid gardener or simply enjoy the occasional store-bought bouquet, roses are undeniably one of the most popular flowers around. But no matter how advanced your green thumb is, roses have a reputation for being tough to grow. However, some varieties are actually very easy to care for, with one of the most low-maintenance breeds being Knock Out roses. The cultivar was bred to include the best characteristics from different species of the plant. The end result? A fuss-free rose that’s disease resistant and blooms all season long. 

How to Plant Knock Out Roses

Knock Out roses aren’t available in seed form—they can only be planted from the container. “Only hybridizers grow roses from seeds,” says Elena Williams of the American Rose Society. “All other roses are grown from the parent plant to be identical. That’s why it takes 8 to 10 years to get a rose from hybridizer to the market.”

1. Pick a sunny location. 
2. Dig a hole slightly larger than the container. 
3. Work the soil at the bottom of the hole so it’s loose and aerated.
4. Remove the rose from its container. 
5. Gently loosen any circling roots at the bottom of the plant. 
6. Place the plant in the hole so the base is level with the soil. 
7. Add soil to the hole around the plant. 
8. Water thoroughly around the base of the plant.

How to Care for Knock Out Roses

Despite being a low-maintenance plant, Knock Out roses require some routine care in order to encourage vibrant blooms year after year. 

Sunlight

It’s best to choose a sunny location when planting Knock Out roses. “Knock Out roses will bloom the best in locations having a minimum of six hours of direct sunlight,” says Heidi Mortensen, rose portfolio manager for Star and Roses and Plants and brand manager for Bloomables.

Soil

While roses are very adaptable to a variety of pH levels, they do best in sandy, loamy, well-draining soil. When grown in containers, roses prefer bagged potting soil. "Preparing your garden bed with 2 to 4 inches of compost mixed in will give your Knock Out roses a great foundation to grow in,” says Mortensen.

Water

Post-planting (and throughout their first season), Knock Out roses will require extra water. Generally, you should water newly planted roses once a week, but check back in regularly to see if they need additional hydration. “Once established, water during dry periods,” says Mortensen. “Knock Out roses are very drought tolerant once established.” 

Fertilizer

Fertilizing your Knock Out roses will encourage new growth. “Use a balanced fertilizer or fertilizer formulated for roses from your local garden center and apply after the first wave of flowering,” says Mortensen. Moisten the soil before fertilizing to avoid burning the roots. You should avoid fertilizing in the late summer, as this is when your roses should be preparing for dormancy and you may encourage unnecessary new growth. Follow the rates and method of application on the product label for specific instructions. 

How to Prune Knock Out Roses

Pruning is an important step when it comes to maintaining Knock Out roses. "Snipping off spent blooms during the growing season will encourage quicker re-blooming," says Williams.

1. Cut back your rose bush with hedges. (Note: cutting it back to be about 12 inches tall will cause it to triple in size by the end of the season).
2. After cutting it back, check your bush for smaller or damaged canes and remove them with hand pruners. 
3. Gather and discard the debris. 

How to Repot Knock Out Roses

Knock Out roses also do well in containers. If you notice that the soil is having a difficult time retaining moisture, it’s time to repot your rose plant. 

1. Choose a container 2 to 3 inches wider in diameter than the current pot.
2. Fill the new container with a quality potting mix. 
3. Gently remove your Knock Out rose from its container. 
4. Loosen the roots.
5. Place your rose plant in your new container and fill in around the edges with soil. 
6. Thoroughly water your rose plant. 

Winterization

Like many plants, Knock Out roses will need some extra care ahead of winter. Clean up foliage and add a fresh layer of mulch or compost around the base of the plant to protect the roots from cold weather. 

Types of Knock Out Roses

Knock Out roses are available in a range of colors and sizes. “Knock Out roses are trialed in 14 different regions around the United States and have proven hardiness, heat, and humidity tolerance in a wide range of climates,” says Mortensen. “The family ranges from zones 5 to 11 and zones 4 to 10, depending on the color.” Two of the most popular types you’ll come across are Double Knock Out roses and Petite Knock Out roses. 

Double Knock Out

This cultivar has 25 to 35 petals and a strong, non-fading cherry red color. “Double Knock Out is our best-selling Knock Out,” says Mortensen. With blooms that last the entire season and an extreme resistance to diseases, it's no wonder that gardeners love this rose type. Double Knock Out roses are hardy in zones 5 to 11. 

Petite Knock Out

The first miniature Knock Out to hit the gardening scene, this stunning rose is a desirable option for the garden. “The most versatile rose ever introduced, enjoy the Petite Knock Out in the border, on the balcony, around the patio, or in floral arrangements,” says Mortensen. “With breakthrough disease resistance and long-lasting flower power, Petite Knock Outs can be enjoyed anywhere.”  This variety is hardy in zones 5 to 10.

Common Pests and Diseases

Although they're designed to be resistant to diseases, Knock Out roses do experience a few problems.

Powdery Mildew

If you notice powdery mildew—a soft white coating—forming on the stems, leaves, or buds of your rose bush, don't panic. The problem generally arises during spring and fall, but becomes less of an issue during the hot days of summer. You can apply horticultural oil to the infected areas to reduce the problem, but generally, powdery mildew will go away during ideal weather conditions.

Black Spot

Black spot is another disease that can affect roses, but it won't threaten the life of your bush. To avoid this, water your roses at the base of the plant—not on the leaves, which can attract certain fungal diseases.

Japanese Beetles

A common insect that affects rose bushes is the Japanese beetle. If you spot them on the foliage of your rose bush, gently pull them off and place them into a bucket filled with warm, soapy water. Prevent future infestations by applying neem oil to the leaves.

Rose Slugs

If you notice holes on the leaves of your rose bush, they may be the result of rose slugs. The tiny green, inch-worm like insects are hard to see but they can affect the appearance of your plant. Apply horticultural oil to the infected areas to reduce the problem.