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 has 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.


Knockout 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 Knockout Rose Bush?

The Knockout Rose 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 bloom 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 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 Knockout Rose bush was 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 Varieties Of Knockout Rose

1. The original Knockout 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 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.

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 Knockout 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 Roses Care So Easy?

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

Deadheading is the practice of cutting off spent flowers to make room for new flowers. Knockout 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 resistant to insects.

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 Knockout Roses remain resistant to the majority of Rose diseases such as powdery mildew, they have become susceptible to a malady known as Rose Rosette Disease.

This problem was once quite rare, but it has taken a foothold because of the proliferation of blossoms found in mass plantings of Knockout Rose bushes.

How To Care For Knock Out Rose Bush?

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. They are remarkably easy-care and very low-maintenance.

Unlike other roses, the Knock Out Rose 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 Knockout Roses as individual plants, settle them into mixed beds of perennials and annuals, create borders and hedges and plant them in large containers.

Generally speaking, they 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 Knockout Roses Care Is Remarkably Easy

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 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 Knockout Roses.

You can plant your roses in either the 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 Beautiful Knockout 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 Knockout Roses enthusiastically 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 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. Knockout Roses like nutrient-rich soil and ample fertilization.

Try foliar feeding your Knockout 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 rose 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: 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 well 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 that have been damaged during the wintertime. Your hearty Knockout Roses will soon be thriving again.

Winter Knockout Rose Care

Like every other aspect of Knockout rose care, winterizing is simple and straightforward.

As we’ve said, these roses are very hardy in mild climates. However, they do require some special care in areas that experience very cold temperatures and/or high winds in the wintertime.

In USDA zones 5b-11, winterization of Knockout roses is very simple, indeed. A bit more caution and preparation are needed in zone 5a.

Winterizing Knockout Roses: Steps in Zones 5b-11

1. Prepare your Knockout roses in advance of the first frost by raking the ground clear around each plant. Do a light pruning to tidy up unruly branches.

2. Provide your roses with a fungicide treatment. In cooler climates (e.g. 5a) use a powdered product. In warmer, drier areas you can use a light treatment of liquid fungicide.

3. Mulch around each of your Knockout plants to help keep the soil temperature consistent. Two or three inches of good quality mulch is advised. Be careful not to let the mulch touch the plant as this will encourage rotting.

4. As spring approaches, begin pruning. You want to perform your spring pruning while your roses are still dormant.

Your late winter/early spring pruning should be fairly aggressive. This is when you remove damaged limbs and dead wood and remove interior stems for better air circulation.

This is also an excellent time to shape your bushes as you will have a clear view of the “skeleton” of each plant.

Special Winterizing Instructions For Zone 5a

Rake and prune your bushes as in steps 1 and 2 above. Have some plastic foam rose cones on hand to protect your bushes against both cold and high winds.

After you have done your initial trimming, try fitting the cones over your bushes. If they don’t fit, more pruning is necessary.

Once you have your bushes properly trimmed to be fitted with rose cones, you can apply a fungicide. In zone 5a, you must use a powdered product because liquid products tend to freeze.

After applying fungicide powder to all of your plants, shape the soil at the base of each plant into a sloping mound. It should be eight or ten inches high and should make contact with the lower stems of the bushes.

With trimming done, fungicide treatment complete and soil in place, you can fit your cones to each bush.

Next, mulch around the bushes with leaves or straw. You should add several inches of mulch to each of your soil mounds. This will provide extra insulation and protection against cold.

Optional Steps

Remember that wildlife gets hungry in the wintertime. If there are deer in your neighborhood, you may wish to take the added step of covering the tops your shrubs with burlap sacks. This will prevent deer from nibbling during lean and hungry times.

If you don’t have plastic foam rose cones, there is an alternative. Just wrap a length of rope around each shrub very lightly. You’ll want to work your way from the bottom of the bush to the top. The purpose of this is to prevent individual limbs from being broken by high winds.

This method doesn’t provide shrub protection against cold.

If you are using the rope method to defend against wind, you will definitely want to add some other sort of protection against cold (e.g. extra straw or foliage and a burlap bag).

Once your roses are covered for the winter, you shouldn’t need to do much to them. Make sure they are well watered in advance of the first freeze.

After the first freeze, they will go dormant and will not need much care until spring.

Questions On Knockout Roses Care

Is there a climbing Knock Out rose variety?

The climbing “Knock Out 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’ up a trellis or any vertical space you want to fill with color.

How tall do Knockout roses 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 does Knockout rose 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 Knockout 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.

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