Knockout roses full sun

How To Take Care Of Knock Out Roses

Rose Breeder Bill Radler created the Knock Out rose bush. It was a big hit, too, as it was a 2,000 AARS and smashed the record for sales of a new rose. The Knock Out® rose bush is one of the most popular roses in North America, as it continues to sell very well. Let’s look at how to care for Knock Out roses.

Care of Knock Out Roses

Knock Out roses are easy to grow, not requiring much care. They are very disease resistant, too, which adds to their appeal. Their bloom cycle is about every five to six weeks. The Knock Out roses are known as “self-cleaning” roses, so there is no real need to deadhead them. Several Knock Out rose bushes blooming along a fence line or at the edge of an island landscaping is a beautiful sight to behold.

Although Knock Out roses are hardy to USDA Zone 5, they will need some winter protection. They are extremely heat tolerant, thus they will do well in the most sunny and hot of locations.

When it comes to growing Knock Out roses, they can pretty much be listed as plant them and forget them roses. If they do get a little out of the shape you like for them along your fence line or garden edge, a quick trimming here and there and they are right back to the form you like blooming all the while.

If no rose bush forming pruning is done to adjust their height and/or width, the Knock Out roses can reach 3 to 4 feet (1-1.25 m.) wide and 3 to 4 feet (1-1.25 m.) tall. In some areas, an early spring pruning 12 to 18 inches (30.5-48 cm.) above the ground works well, while in areas with harder winters they may be pruned down to around 3 inches (7.5 cm.) above the ground to remove the dieback of the canes. A good early spring pruning is highly recommended to help get the top performance out of these fine shrub rose bushes.

When caring for Knock Out roses, feeding them a good organic or chemical granular rose food for their first spring feeding is recommended to get them off to a good start. Foliar feedings from then on until the last feeding of the season works just fine to keep them well-fed, happy and blooming. Without a doubt, there will be more and more rose bushes added to the Knock Out family of rose bushes as research and development continues. Some of the current family members are:

  • Knock Out Rose
  • Double Knock Out Rose
  • Pink Knock Out Rose
  • Pink Double Knock Out Rose
  • Rainbow Knock Out Rose
  • Blushing Knock Out Rose
  • Sunny Knock Out Rose

Again, the Knock Out line of rose bushes is bred to be low maintenance and low need for care rose bush.

Pruning Roses: 8 Steps for Healthy Rose Bushes

Learn how to trim rose bushes — it’s not as difficult as you think! By Linda Hagen

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Bypass shears are ideal for pruning roses — their overlapping blades make a clean cut. Photo by: Fotoschab | Dreamstime.com.

When you know the basics of pruning roses, even inexperienced gardeners can achieve beautiful results. Don’t be intimidated by pruning—the rules and warnings are mainly for those who grow roses for specimens or exhibits. But for the casual gardener who simply wants beautiful, healthy rose bushes, there are really only a few fundamentals to follow.

WHAT YOU’LL NEED

  • Good gloves — Buy on Amazon
    Gauntlet-style recommended for extra protection up your forearm.
  • Bypass shears, not anvil — Buy on Amazon
    Bypass blades overlap and make a clean cut; anvil blades meet and can crush or damage canes.
  • Heavy long sleeves
    The right clothing will prevent getting “bit” by the thorns.

WHEN TO PRUNE ROSES

Spring:

Major pruning should be done in early spring, after the last frost in colder climates, by following the 8 Basic Pruning Steps below. You can also let the roses tell you — when they start to bud or leaf out, it’s time.

If you’d like to mark your calendar, or set yourself a pruning reminder, here are general estimates of when you might expect your last frost to occur:

  • Zones 3 and 4 – May 1 to May 31
  • Zones 5, 6 and 7 – March 30 to April 30
  • Zone 8 – Feb 22 to March 30
  • Zone 9 – Jan 30 to Feb 28
  • Zone 10 – Jan 30 or earlier

For a more specific prediction of your last frost date, use this frost date calculator from The Old Farmer’s Almanac.

More Ways to Keep Your Roses Healthy

  • Get rid of aphids
  • Treat powdery mildew
  • Control Japanese beetle infestations
  • Improve your soil

Summer:

Dead flowers can be cut back at any time in summer. Carl Bennett, longtime Rose Breeding Manager of David Austin Roses, says that during the flowering season, deadheading will encourage more blooms and maintain an attractive shrub.

Fall:

After the first killing frost, trim longer stems to keep them from snapping in winter storms. Keep rose bushes from being top heavy to protect them from being uprooted in strong winds. Crossing branches that could be damaged by rubbing together should also be trimmed back. Take it easy though, as too much pruning can stimulate growth, and that new growth may be damaged by freezing weather. Remove any dead or diseased branches and foliage, and clean your cutting tools well to prevent transferring disease to another plant.

8 BASIC PRUNING STEPS

You’ll be surprised to learn that modern roses don’t need as much pruning as you think. Follow these steps to ensure your roses will thrive:

1. Remove all remaining leaves.

This allows you to see the structure of the bush and clearly see all the canes (stems). This step also removes any pests or diseases that may have been hiding over winter in the foliage.

2. Start with dead wood.

How do you know its dead? Cut into it — brown is dead, green is living. Cut any dead wood back to the base.

When pruning roses, your goal should be to open up the center and create a vase-like shape. Photo by: Avalon/Photoshot License / Alamy Stock Photo.

3. Open up the center of the plant.

Take out crossing branches which can rub, causing damage and encouraging disease. The goal is to have upward-reaching branches with an open structure in a vase-like shape.

4. Remove any thin, weak growth.

The basic rule of thumb is to remove anything thinner than a pencil.

5. Prune the remaining canes.

Prune by cutting 1/4” to 1/2” above an outward-facing bud eye (a small bump found where a leaf would meet the stem). New stems grow in the direction of the bud and the goal is to encourage them to grow outward, not inward. Make cuts at a 45-degree angle sloping away from the bud, allowing water to run off.

6. Seal fresh cuts.

Protect freshly cut canes from rot and rose borers by sealing the wounds with a compound like Bonide’s Garden Rich Pruning Sealer.

7. Clean up.

After pruning, make sure to clean up the surrounding area underneath. All leaves and cut branches should be disposed of as diseases and pests could be lurking.

8. Feed your roses.

Roses are “big eaters” and need proper nutrition, so feed them with a long-lasting fertilizer like Jobe’s Organics Fertilizer Spikes.

Oso Easy Double Red™.
Photo: Proven Winners® ColorChoice®.

HATE PRUNING, BUT LOVE ROSES?

If the steps above sound daunting, you don’t have to forgo growing roses. Landscape roses are a simple way to add lots of color to your garden. Unlike hybrid teas, these resilient plants don’t require precise pruning or other care.

Pruning landscape roses is easy: come spring, cut out any old or dead wood and then trim the whole plant back by about half its height. That’s it! No need to be fussy with these vigorous, easy going varieties.

The Oso Easy® series is a great choice if you don’t want to deal with heavy pruning or constant deadheading. Plus, they’re also highly disease resistant—which means no spraying either!

PRUNING FAQS

Pruning height:

Prune to the height you want your rose bush to be, keeping a fairly consistent height throughout. If it is in the back of a border, leave it a little higher; for the front of a border, trim lower. For hybrid teas in particular, the lower you prune, the bigger the flower and longer the stem — good for cutting and exhibiting. Leave them a little taller and you will tend to get more blooms, although smaller and on shorter stems.

Climbing roses:

Most of the same rules apply to climbing roses but there are a few differences, mainly the way that climbers grow. Climbing roses have 2 types of canes, main and lateral. The main canes come directly from the base and should never be pruned. Climbers put their energy into growing first and flowering second. Therefore, if energy is spent on regrowth of the main canes, it will not flower. The lateral canes are the ones that produce the flowers and pruning these will encourage blooming. There’s no need to fuss about pruning to the outward-facing buds, as shaping climbing roses in this way is unnecessary. Lateral canes can be pruned anytime of the year to keep the climber in shape. For more information, see: Pruning Climbing Roses.

Knock Out Roses:

Just like climbing roses, pruning rules for Knock Outs are similar, but with a few exceptions. Knock Outs are generally ready for their first pruning in their second or third season, after reaching a mature height of 3-4 feet. The timing of pruning is the same as other roses, in late winter or early spring when buds start to form. Knock Outs bloom on new growth, so old, dead, or broken canes should be the first to go, cutting them back to the base. Overall, Knock Outs can be taken back by about 1/3 of their height, keeping in mind overall finished shape. Knock Outs tend to grow in phases (bloom – rest – bloom). If a mid-season trim is in order, it is best done following a blooming period while in the resting phase. Deadheading will also help to stimulate new bloom clusters and overall growth. Knock Outs tend to produce a lot of rose hips that inhibit flowering (triggering dormancy), so trimming these off will keep your Knock Out blooming.

In warmer climates, leaving the rose hips on through fall and winter helps trigger dormancy.

Rose hips:

In warmer climates, leave rose hips (the small, round, orange or red fruit produced after pollination of the flowers) on through the fall and winter; they tell the rose it’s time for dormancy. So instead of deadheading the last blooms of the season, simply remove the petals, allowing the rose hips to form. In colder climates, roses are naturally triggered to go dormant, but in warmer climates they may need this nudge.

Pruning is vital to the health of the rose bush, it helps prevent disease by removing areas that may harbor infestations and also encourages flowering. Your roses may look stark after a good pruning, but roses grow very prolifically and will fill in quickly. It’s almost impossible to kill a rose bush by over-pruning. Following these few simple rules will ensure your roses are happy, healthy, and will provide you with a season of beautiful blossoms.

Last updated: January 17, 2020

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Knock Out roses can be pruned, too

By Dan Gill

LSU AgCenter Horticulturist

(08/25/17) The Knock Out rose has become amazingly popular over the past 10 years. This rose has singlehandedly changed the market for roses since its introduction and ushered in a whole new way to look at roses and use them in our landscapes.

Its outstanding characteristics are well documented — excellent disease resistance, more frequent reblooming, showy clusters of single cherry red flowers, dark green attractive foliage and a shrubby growth habit that works well in the landscape. Knock Out roses, along with many other excellent rose cultivars in the landscape rose and old garden rose categories, tend to be used in landscape plantings like any other shrub. And they play that role very well.

These plants are remarkably resilient in landscape planting. You will see black spot and yellowing leaves on occasion, particularly during rainy periods. Powdery mildew may show up during ideal weather conditions. As a result, I’ve had gardeners complain that they thought Knock Out roses did not get foliar diseases.

These roses, however, are resistant, not immune, to diseases. That means when more susceptible cultivars are having major disease problems, you will tend to see fewer disease problems on more-resistant types, like Knock Outs. But under hot, humid, rainy weather conditions, even resistant rose cultivars will show spotting and yellowing leaves. But the plants will recover and be fine without fungicide treatments.

Once established, they are remarkably resilient and drought-tolerant. Notice the Knock Out roses thriving around gas stations. They do not need or want to be pampered.

One issue, however, is size. Many people purchase this plant with a tag that indicates the mature size at about 4 feet tall and wide. In fact, they can easily grow to 6 by 6 feet or more. The good news is that pruning them is not difficult and, done about twice a year, will help keep your bushes more compact.

Like all everblooming roses we grow in Louisiana (hybrid tea, grandiflora, floribunda, China, noisette, tea, Bourbon, landscape roses, miniature roses and others), Knock Out roses should receive two major prunings a year.

Use sharp bypass-type hand pruners when pruning roses. They make clean cuts and minimize damage to the stems. Wear a sturdy pair of leather gloves and long sleeves because no matter how careful you are, thorny roses can painfully puncture or scratch your hands and arms. Should you need to cut canes larger than one-half inch in diameter, you should use loppers.

The first pruning is done anytime from late January to mid-February. Pruning any later will delay the outstanding spring and summer flowering. There is no set way to prune a Knock Out rose (or other landscape roses). It depends entirely on the desires of the gardener and the situation.

If you want your roses to grow large to form a screen, you would do only light pruning and cut out any dead wood. In a situation where the bushes have grown too large, decide what size they need to be for the location. Cut the bushes back about 1 foot shorter than you want them to be (within reason, you should never cut them back shorter than 2 feet tall). A general recommendation for the late-winter or early spring pruning is to reduce the height of the bushes by about one-half to one-third.

You may do this even if the shrubs are sending out new growth. If the winter is really mild, they may even be producing some flowers, but you still need to prune. Put any flowers you cut off in a vase to enjoy indoors. Try to shorten canes back to a leaf or dormant bud, but you don’t have to be too picky. I’ve heard of extensive plantings being pruned successfully with electric hedge trimmers. Cutting back these roses stimulates vigorous new growth and improves flowering.

We do not prune roses back hard during the summer. They are stressed by the intense heat of June, July and August. (You will typically notice flowers are smaller and not as pretty.) However, where size control is needed, it is possible to manage the size of rose bushes to some degree during the summer when removing faded flowers — called deadheading.

Typically when we deadhead, we make the cut just above the five-leaflet leaf closest to the flower cluster (or the first five-leaflet leaf you come to as you move down the stem from the cluster of flowers). To control size during summer, however, you may cut back to just above a leaf farther down the stem — down about 6 to 8 inches below the faded flowers — when you deadhead.

Another opportunity to cut the bushes back arrives now in late August to early September. Again, you don’t have to be too fussy about this. This pruning is not as severe as the late-winter pruning. Plants are generally cut back by about one-third their height, more or less, depending on how much control is needed. Don’t forget to remove any dead canes when you cut the bushes back. Fertilize the bushes immediately after this pruning.

The Knock Out family of roses, and other excellent everblooming landscape roses and old garden roses, are great additions to our landscapes. Don’t forget to prune them in late August (north Louisiana) or by early September (south Louisiana). All repeat-flowering roses benefit from late-summer pruning. It stimulates vigorous new growth and better flowering, helps control size, keeps the bushes full and shapely, prevents them from looking so leggy and removes dead growth.

Rose pruning time by kaysare

TheGardenLady received this question from Keith.

I live in Bartlesille. When should I prune my Knock Out Roses?

TheGardenLady has been getting a number of questions about when to prune Knock Out Roses. First of all, if any rose has Dead, Diseased, Damaged, Spindly or Weak branches, these branches can be pruned at any time of the year.

The joy of having Knock Out Roses is that they are easy maintenance roses so you almost don’t have to prune them. In fact, you should not even bother to prune them the first year and during the second year they only need light pruning to shape them.

After that if you want to prune harder to promote healthy growth and encourage lots of flowers, prune your Knockout Rose in early spring after the last hard frost in your area. A hard frost is anything below 24 degrees. To check out your Hardiness Temperature Zone go to the Arbor Day Temp. Zone map and write in your zip code to find out the temperature zone you are in. See here.

Below is a chart with Average Last Frost Dates and Average First Frost Dates to help you once you know the Hardiness Temperature Zone where you live.

ZONE AVERAGE LAST FROST DATE AVERAGE FIRST FROST DATE

Zone 3 1 May / 31 May 1 Sep / 30 Sep

Zone 4 1 May / 30 May 1 Sep / 30 Sep

Zone 5 30 Mar / 30 Apr 30 Sep / 30 Oct

Zone 6 30 Mar / 30 Apr 30 Sep / 30 Oct

Zone 7 30 Mar / 30 Apr 30 Sep / 30 Oct

Zone 8 28 Feb / 30 Mar 30 Oct / 30 Nov

Zone 9 30 Jan / 28 Feb 30 Nov / 30 Dec

Zone 10 30 Jan or before 30 Nov / 30 Dec

Zone 11 Free of Frost throughout the year.

According to the Knock Out Rose website all you have to do to prune your Knock Out Rose is to take hedge trimmers and shear the shrub down to about 1/3 or 1/2 its current height. You can cut it down to 12-18 inches above the ground.

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Filed under Knock Out Roses, Pruning

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