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How to Care for Knockout Roses

Roses are absolutely some of the most beautiful flowers. They smell amazing too! One of the reasons rosewater everything is so popular right now has to be the lovely fragrance that is characteristic of roses. Possibly the best roses available? Knockout Roses!

Knockout Roses have been extremely popular since their creation. 

How to Care for Knockout Roses

They work great in pretty much any planting setting so you can be creative with their placement! 

Following you'll find our complete guide explaining how to care for knockout roses. 

A Little Bit about Knockout Roses

A little background on Knockout Roses first before we learn how to care for knockout roses. Created by Bill Radler in 1989 and officially begun selling in 2000. In fact, they won the All American Rose Selections award in 2000. 

Knockout Roses have become widely popular for several reasons:

  • hardiness
  • disease resistance
  • low-maintenance
  • floriferous

They bloom every 5 to 6 weeks from Spring until the last frost in the fall. They are low-maintenance and are known as "self-cleaning."

They like the heat and a good amount of sun, but do require some protection during the winter. 

Knockout Roses grow as a shrub or bush and can get to 3 to 4 feet wide and 3 to 4 feet high. They don't have the traditional rose scent, but have a lovely fragrance of their own. 

There are 11 varieties of Knockout Roses 

  • Original Knockout Rose (Rosa Radrazz) which blooms in shades of red from cherry to magenta
  • Double Knockout (Rosa Radtko) produces double blooms in cherry red and tolerates cold better than the original
  • Double Pink Knockout (Rosa Radtkopink) produces a double blossom in pink
  • Sunny Knockout (Rosa Radsunny) blooms are a bright yellow
  • Rainbow Knockout (Rosa Radcor) produce single blooms that are pink with a yellow center
  • Pink Knockout (Rosa Radcon) produces a light pink bloom
  • The Blushing Knockout (Rosa Radyod) blooms in a very pale pink shade
  • Coral Knockout Rose (Radral) produces a bloom that is brick orange fading to coral
  • Peachy Knockout Rose (Radgor) is shell pink with a yellow center
  • White Knockout Rose (Radwhite) is a bright white
  • Petite Knockout Rose (Meibenbino) is a petite version of the original but in a fire engine red

There is one additional variety of the Knockout Rose, the Rosa Radwin. This variety is a climbing rose that will climb as high as 10 to 12 feet. It prefers full sun and is a bright fire engine red. Another fun fact, its foliage turns burgundy in the fall! Now, let's learn how to care for knockout roses. 

How to Care for Knockout Roses: Planting

It's all about starting with a good foundation! 

Tools Needed

Lopping shears
Pruning shears
Leather gloves to protect from thorns
Wheelbarrow for off cuts

pruning tools needed for caring for knockout roses

When to Plant

Plant in early spring or in the fall while the plant is still dormant. Be sure to keep the soil around the plant moist for the first month after planting so the roots can become well-established. 

Where to Plant

Zones 5 through 11 should find it easy to grow and care for Knockout Roses. 

Knockout Roses need about 5 to 6 hours of morning sun, but otherwise enjoy the shade just fine. They are sensitive to extreme heat and are not drought tolerant. 

How to Plant Knockout Roses

You can plant Knockout Roses three ways: container, flat garden bed or raised garden bed.

Wherever you decide to plant, be sure you provide for plenty of drainage. For example, if you plant in a container, it must be large enough to accommodate the root system and drain off excess water.

Raised garden beds are always the best for drainage, but as long as you pay attention to how to care for knockout roses, anyplace will do just fine. 

Spacing

Knockout Roses grow as a bush or shrub and will need about 4 feet between them. 

Planting

Begin by tilling the area you plan to plant the roses in to a depth of at least 12 inches. 

  • Dig--twice as deep and twice as wide as the root system
  • Add--layer of peat moss and organic compost to the hole and mix well with soil to provide nourishment and help drain water. pH level of the soil should be around 6.5. Be sure to test your soil and make adjustments as needed
  • Insert--plant in the hole, leaving 1 inch stem above the soil
  • Backfill--hole until plant is held firmly in place
  • Soak--with water and then add soil to level the ground around the base
  • Mulch--layer around the base of the plant

For more on pH levels: The Importance of Your Soil's ph Levels: A Guide to Lawn Maintenance

mulch options for knockout roses

How to Care for Knockout Roses: Ongoing Maintenance

One of the reasons that Knockout Roses are so well-liked is that they are relatively low maintenance, especially compared with other species of roses. There is still some maintenance required, however, as you'll see below in the next section of how to care for knockout roses. 

Deadheading

It isn't at all necessary to deadhead Knockout Roses. New growth will actually push the dead roses out of the way. However, many rose enthusiasts still prefer to deadhead because it does make a tidier looking plant. 

Pruning

Pruning is important because Knockout Roses grow quickly!

Hard-prune in early Spring. Oftentimes, February is the time to hard-prune those roses. But, as things can differ a bit year to year and climate to climate, the best way to tell when it is time is when the new sprouts are about one-quarter to one-half inch in size. 

Remove the dead and broken branches. 

Open up the middle of plant by taking out the unproductive branches. This helps the air circulate to the productive branches. 

Shape the plant by following its natural lines. It should make a "V" shape. 

Then cut back the healthy branches by one-third to one-half. It does seem like a lot, but don't worry, once the rose bush starts growing, it will grow very quickly!

Throughout the remainder of the growing season you'll only need to make small trims if it starts losing its shape. 

Watering

Every plant has different water preferences. Knockout Roses again are low-maintenance.

  • Only once per week, unless especially hot, then twice per week.
  • Top 2 inches should be wet.
  • No standing water, mulch well around the base to keep moisture in the soil.
  • Do not get water on foliage.
  • Do not water in the evenings.
  • Soaker hose or drip irrigation works best.

Fertilizing

Any plant will require some feeding or fertilizing. In this section of how to care for knockout roses, we'll learn all about fertilizing. 

Use natural organic fertilizer on young plants because they have a more delicate root system. Chemical fertilizers are likely to burn the root system of young plants. 

How to Fertilize and Feed Knockout Roses

via: Wikihow

After the first bloom you can use a chemical fertilizer and will likely only need one application. 

When looking for a chemical fertilizer look for high nitrogen amounts. The numbers on the packaging indicate the Nitrogen-Phosphorous-Potassium content.

Continue with a natural fertilizer every weeks until about 6 to 8 weeks before the first frost.   

Spread fertilizer in a circle around the plant---in a circle about 6 inches from the plant and work in the top 2 inches of soil

Fertilizer Tips

Be sure to read the directions on liquid fertilizers as the amounts vary. 

Also, Knockout Roses really like coffee grounds as a natural fertilizer.

Foliar feeding with Epsom salt for brighter color

Use fertilizers specifically made for roses

Again, remember to stop all fertilization 6 to  weeks before the first frost. 

Knockout Roses Diseases

Knockout Roses were bred to be quite hardy and disease resistant, and they are much more so than their relative rose cousins.

However, there are a few diseases that can afflict Knockout Roses, but they are treatable and even more important, preventable. 

Black Spot Disease

Black Spot Disease is a fungus caused by moisture. It appears as circular black spots on the stem or leaves. It can destroy the entire plant, so treatment is needed immediately.

To treat Black Spot Disease, prune the infected parts as soon as possible. Afterward, be sure to mix up some bleach water and clean your pruning shears to avoid spreading the disease further.

To prevent Black Spot Disease, avoid late evening watering as well as avoid getting water on the foliage. 

Botrytis Blight Disease

Botrytis Blight is another fungal disease caused by moisture. Also called ‘gray mold’ this disease prevents new buds from blooming. The new buds will also be covered in a grayish mold.

Roses that have already bloomed will turn a brownish-yellow and will begin drooping. To treat ‘gray mold,’ remove the affected parts of the plant immediately.

Because moisture is the culprit, make sure to keep the foliage free of moisture when watering. 

Powdery Mildew

Powdery Mildew appears as a white powdery substance on the foliage and stem of the plant. As another fungus, powdery mildew stunts the plant's growth and causes the leaves to fall off.

To treat, remove the affected parts of the plant. Also, keep the ground clear of debris. To prevent, only water at the base of the plant, keeping the foliage dry. 

Rust on Knockout Roses

Rust looks like a powdery substance in an orange hue, gaining the name “rust.” As it grows the powdery substance will create large rust-colored spots and in the fall and winter will turn black.

It is another fungus that is also caused by moisture. To treat rose rust, treat with a natural or chemical fungicide. Also, be sure to remove any dead leaves or roses to keep it from spreading.

To prevent knockout rose rust do not water late in the evening and only water the soil at the base of the plant. Avoid getting water on the foliage. 

How to Care for Knockout Roses: Winterizing

Most zones that Knockout Roses are appropriate for will not need to winterize. However, if you live somewhere with especially harsh winters, there are several steps you should take to protect your roses for the next growing season. 

In some climates, Knockout Roses will bloom just about all year long!

There are two sets of guidelines for winterizing Knockout Roses. 

For milder winters, such as those in Zones 5b-11

Rake around the base to get any dead or loose debris out of the way. 
Then prune just a bit to clean things up. 
Add a fungicide to the plant to help keep the plant healthy during the winter. 
Add two to three inches of mulch around the base, but not touching the base. 
Be sure to keep well-watered until the first freeze. 
That's it until it's time for the hard-prune in February!

Caring for knockout roses in winter

via: https://www.landscapemulch.com

For harsh winters such as in Zone 5a

Rake around the base to remove debris.
If possible, locate plastic foam rose cones. 
Prune until the rose cones fit. 
Once properly pruned, apply a powdered fungicide. 
Then shape the soil at the base into a mound, about 8 to 10 inches high. 
Place the rose cones over the plant. 
Mulch around the base with leaves and/or straw, several inches high.
Be sure to keep well-watered until the first freeze. 
That's it until it's time for the hard-prune in February!

After the frost in the spring, remove the straw and trim that areas that were damaged by the wind and cold. 

Tips for Winterizing in Harsh Weather

Cover the tops of rose bushes with burlap sacks.
If no plastic foam rose cones are available..
Use rope instead of cones. Wrap lights from bottom to top. This will only protect from the wind. 
Use burlap bags for insulation. 

Knockout Roses are easy to grow and care for

Summarising How To Care For Knockout Roses 

As you now know how to care for Knockout Roses is very easy. They are designed to tolerate heat and are hardy and durable. I hope these steps make taking care of your roses even easier! This variety of roses is perfect for those without time to dedicate to delicate plants.

Watering on a regular basis, feeding once a month, and pruning a few times a year will go a long way to ensure your bushes blossom for years to come. Defend it from the winter and your landscape will be breath taking each season.

Do you have any awesome tips for taking care of Knockout Roses? Tell us about them in the comments!

About the Author Ann Katelyn

I'm Ann Katelyn, Creator and Chief Author of Sumo Gardener. Since I was a child I've always been fascinated with plants and gardens, and as an adult this has developed into my most loved hobby. I have dedicated most of my life to gardening and started Sumo Gardener as a way to express my knowledge about gardening with the hope of helping other people's gardens thrive.

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