Knockout Roses Care: [5 SMART TIPS] For Growing Beautiful Knock Out Roses

Did you know that Knockout Roses care is so easy, many believe the Knock Out helped save the popularity of roses?

The Knockout Rose is the most popular type of rose in the USA today. It was created by an amateur rosarian (rose enthusiast) by the name of Will Radler in Milwaukee in 1989.

It’s popularity is primarily due to the fact it is so very hardy, easy to raise and easy to care for.


Knock Out Roses are actually so easy to grow that they are used in parking lot planters, road medians and other areas where plants are basically neglected.

These cheerful, abundantly blooming roses thrive in these difficult conditions.

On the downside, Knock Out Roses do not make good cut flowers because they have thin stems and don’t last long when kept in water.

In addition, rosarian purists claim that the Knockout Rose bush does not have any scent. Radler is quick to point out that it does indeed have a scent, but it is not the classic rose scent.

He says that it has a light, fruity, sweet scent that is quite pleasant.

Although there are some rosarian purists who find these small faults with the Knockout, it is generally a very popular choice for the home garden.

When compared with other types of roses, Knockout blooms more frequently and more abundantly and is far easier to care for than the typical fussy rose.

How Did Radler Create The Knock Out Rose Bush?

The Knock Out Family of Roses is Radler’s crowning horticultural achievement. He has been a rose enthusiast since the age of nine and is now in his 70s.

He began trying to develop an easy-care rose at a very early age. In fact, he says that fixing roses was one of his first horticultural goals.

Radler approached the problem in a unique way by selecting and propagating roses for hardiness and disease resistance first and flower production second.

He began his project in 1974 and only began meeting with success in the late 1980s when he developed the strain he labeled 89 – 20.1.

This proved to be the breakthrough rose that was easy to grow, disease-resistant and capable of producing billowing clouds of lovely, pinkish red roses throughout the entire summer.

It was not until the early 1990s that Radler’s new strain of rose took off and attained the name “Knockout”.

In 1992 a company known as Star Roses & Plants near Philadelphia signed a contract with Radler to begin testing on his new rose, a process which took eight years.

With the required testing complete, the company filed for a patent and named the new, easy-care rose Knockout. Sales began in the year 2000.

It became quickly apparent that Knockout Rose bushes would be wildly popular. In fact, the stellar performance of the Knockout Rose bush allowed it to be named the All American Rose Selections winner in the year 2000.

Today, with over 90 million plants sold, they have made Radler a wealthy man. These easy-care roses are now available in seven different varieties in nurseries and home improvement centers across the nation.


The 7 Rose Knockouts In A Variety of Colors

1. The original Knockout plant is the Rosa Radrazz. This hearty plant produces single blossoms that range from cherry red to magenta in color.

2. Rosa Radtko is called the Double Knockout rose tree because it produces double blooms. Like the original Knockout, the blossoms are cherry red. This variety tolerates cold a little bit better than its predecessor.

3. Rosa Radyod produces a very pale pink single blossom. It is also called Blushing Knockout Roses.

4. Rosa Radcon is a light pink variety that produces single blossoms. It is also known as the Pink Knockout.

5. Rosa Radtkopink, a.k.a. the Pink Double Knock Out rose is the double blossom version of the pink variety.

6. Rosa Radsunny produces cheery, fragrant yellow roses. It is also known as the Sunny Knockout.

7. Rosa Radcor is a smaller pink and yellow variety that is also called the Rainbow Knockout. It produces single pink flowers with a yellow center.

What Makes Knockout Rose Care So Easy?

One of the main advantages of the Knockout Rose tree is that they don’t require deadheading.

Deadheading is the practice of cutting off spent flowers to make room for new flowers. Knock out roses simply push the old roses out-of-the-way and make room for the new on their own.

One plus in Knock Out roses care – they require little or no use of pesticides because they are naturally disease resistant and insect resistant.

Likewise, they are disease resistant to most rose problems like the dreaded “Black Spot.”

This quality makes them very popular with all gardeners, but especially so with those who wish to keep an organic lawn and garden.

It is worth noting that, although Knockouts remain disease resistant to the majority of Rose diseases such as powdery mildew, they have become susceptible to a malady known as Rose Rosette Disease.

Rose rosette disease is defined as a condition that causes roses to produce strange deformed leaves, flowers and stems. The disease is actually a virus that requires the eriophyid mite to spread and transfer the disease.

The Rose Rosette disease problem was once quite rare, but it has taken a foothold because of the proliferation of blossoms found in a mass planting Knock Out Roses.

How To Care For Knock Out Rose Bushes?

If you already know a great deal about roses, you can toss most of your knowledge out the window!

The question of  “How To Care For Knock Out Roses” is simple. These roses offer remarkably easy-care and very low-maintenance.

Unlike other roses, the Knock Out Rose plant bush does well in partial shade to sun.

They can thrive in a wide variety of settings from zones 7 to 11 blooming from springtime to the first frost. They love coffee grounds and banana!

You can enjoy carefree beauty of Knockout Roses by growing them as individual plants, settle them into mixed beds of perennials and annuals, create borders and hedges and plant them in large containers.

Generally speaking, these roses maintain an upright, round, compact shape that grows to about 3-4 feet high by 3-4 feet wide. In extremely ideal conditions, and left totally un-pruned, they can sprawl out to 5-foot tall and 5 feet wide.

Getting Started With Knock Out Rose Care Is Remarkably Easy

How to plant Knock Out roses!

These hearty roses are tolerant of a wide variety of conditions. They are happy in partial shade and in full sun and can tolerate most variations in temperature.

They are sensitive to extreme heat so they are not drought tolerant. If you live in an area that has a very punishing sun you will probably find that your roses do better in partial shade.

It’s good to start out with a well-prepared bed by Rototilling the area where you wish to plant your Knockout Roses to a depth of at least 12 inches.

Be sure to work lots of good organic compost into the well-drained soil to provide nourishment and good drainage.

Remember that roses need lots of nitrogen, and your soil pH level should be about 6.5. Test and amend to ensure these conditions for the best results with Knock Out Roses.

You can plant your roses in either the early spring or in the fall. They are dormant at either time.

New planting should be kept evenly moist during the first month following planting. This will help your new rosebush establish itself well.

5 Smart Steps To Maintain & Care For Knock Out Roses

1. PRUNE: Knockout Roses are generally very fast-growing, and the biggest maintenance job you will have with them is pruning.

They respond very favorably to good pruning technique. It’s best to do your pruning in February.

Begin by removing broken branches and deadwood and then commence shaping your rosebushes. You should open up the inner portion of the bush by taking out interior branches that have become unproductive.


Follow-up by trimming back healthy branches by approximately a third to a half of their original length.

Remember pruning rose bushes is not like shearing hedges. Shape your bushes carefully by following their natural lines.

When you prune your Knock Out Roses aggressively in the early spring, you can expect them to grow back rapidly and bloom with great vigor throughout the spring and summer.

It’s best to perform this dramatic early spring pruning every year and then just provide little trims in between to shape your plants and ensure symmetrical growth.

To see a collection of interesting videos about the best way to prune your Knockout Roses, here.

2. FERTILIZE: You should fertilize your roses monthly from springtime to fall. Knockouts like nutrient-rich soil and ample fertilization.

With a quick search, you’ll be able to find the best rose fertilizer for Knockouts.

Try foliar feeding your Knock Out roses Epsom salt as well. What does Epsom salt do for your roses? The reward – blooms with brighter, more vibrant color.

When selecting an organic matter or Knockout roses feed, use a fertilizer blended specifically for roses.

Early in the spring, you should give them two or three pounds of nitrogen-rich fertilizer for every hundred square feet of soil. Boost this with one or two pounds per hundred square feet monthly through the middle of August.

3. HYDRATE: Water established rosebushes to a depth of approximately an inch once a week rather than watering them lightly and frequently.

4. CONSERVE MOISTURE: Mulch well around your rosebushes to prevent evaporation of moisture.

Always water with a soaker hose or slowly trickling hose rather than a sprinkler. Sprinkling roses can cause moisture to collect on the foliage and leads to disease.

5. PROTECT AGAINST FREEZING: Worried about preparing knockout roses for winter? In the wintertime, your Knockout Rose bush will need little if any care. They are quite hardy from zones 9 to 11.

If you do have harsh winters in your area, you should insulate your bushes during winter by blanketing them in several inches of straw around the base.

After all danger of frost this past, pull the straw away and trim back any areas damaged during the wintertime. Your hearty Knockout will soon be thriving again.

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Questions On Knockout Care

Is there a climbing Knock Out rose plant variety?

The climbing Knockout Rose – Rosa ‘Radwin’ PP#19310 was introduced in 2008 from the same originator of the Knock Out® Rose.

  • A floriferous climber reaches 10-12 feet and loves full sun.
  • Winter hardy to USDA hardiness zone 5.
  • A non-fading fire engine red color handles heat well.
  • The foliage becomes a deep burgundy red in the fall.
  • Grow Rosa ‘Radwin’ as a trellis plant or any vertical space you want to fill with color.

How tall do Knock Outs grow?

Most Knock Outs reach 3′ to 4′ feet tall with a width of 3 to 4 feet as well.

I have seen Knockouts planted in the landscape that homeowners have not pruned down in spring reach a height and width of 5′ – 6′ feet overall.

Pruning keeps them inbounds and manageable.

When Do Knockout bushes bloom?

The Knock Outs blooming season is a long one running from Spring up until the last frost.

They rebloom every 5 – 6 weeks and do not need deadheading. However, by deadheading spent flowers the plant will look tidier and cleaner.

Where to buy Knockout Rose bushes?

The entire family of Knock Out Roses is available at most garden centers and online throughout the country.

Knock Out Roses Add Easy Beauty To Your Landscape

With many beautiful and affordable varieties available, it’s easy to see that adding hardy, cheerful Knock-out Roses to your roadside, yard, and garden is a smart choice.

For very little outlay of cash, you can enjoy a bounty of beautiful, lightly fragrant blooms year after year.

This sort of addition to your landscape enriches your personal enjoyment along with the monetary value of your home.

Sources: 1 | 2 | 3 | 4

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