Is Knockout Rose Down for the Count?

April 21, 2013 | By | Comments (89)
Knockout rose

Enough color to knock your socks off — that’s ‘Knockout’ rose. Photo by Steve Bender.

Introduced in 2000, ‘Knockout’ rose quickly became the best-selling landscape plant in the country. It had everything — showy, continuous blooms; compact growth habit; tough-as-nails constitution; and, best of all, no need to spray for black spot disease. But now, nature has tossed green kryptonite into Superman’s garden. And ‘Knockout’ rose may just get its bell rung.

A Deadly Threat
‘Knockout’ rose (the original single red, shown above, plus a bunch of newer colors) owes its uber-popularity to the belief that it’s the first “no maintenance” rose — perfect for the lazy gardener in all of us. People think it needs no watering, spraying, pruning, or fertilizing — EVER. It’s like an actual living plastic plant. You just stick it in the ground and it will bloom, bloom, bloom with zero care from you. How marvelous.

Unfortunately, this belief is dead wrong. ‘Knockout’ does need water, fertilizer, and pruning. And now it’s facing a disease so serious that its very survival is in question. Rose rosette disease.

Rose rosette

Rose rosette disease. Photo:

This is what rose rosette looks like and it’s not pretty. A formally healthy plant starts producing Medusa-like bunches of bright-red new shoots. The shoots bloom, but the flowers look distorted. As rose rosette spreads through the plant, the rose gradually dies back, until it completely croaks. Down for the count.

What Causes Rose Rosette?
Rose rosette is caused by a virus first discovered in the western U.S. around 1940. The virus is principally spread by tiny eriophyid mites — so tiny, in fact, that they literally blow into gardens on the wind. When they feed on a rose, they transmit the virus. At that point, the jig is just about up.

Now here’s a surprise. There was a time when rose rosette was considered a savior, not a plague. Any of you remember the infamous “living wall,” aka the multiflora rose? A vigorous, arching import from Japan, it produced pretty white flowers in spring and thousands of small, bright-red rose hips in fall. It grew so thickly that highway departments in the East and Midwest actually planted rows of it down highway medians. Even a tractor-tractor couldn’t smash through. Cattlemen also used it to contain cattle.

But you know what they say about good intentions. Birds ate the red rose hips and spread multiflora rose everywhere. It proved to be an awful, noxious weed. States banned it, but it was too late. The entire eastern U.S. was destined to be smothered by the stuff, unless a control could be found.

It was. Rose rosette disease.

Wahoooo!!! Rose rosette killed multiflora rose faster than a van filled with nuns kills a good kegger. Unfortunately, when rose rosette ran out of multiflora roses, it looked for something else to feast on. The target? ‘Knockout’ rose and other shrub roses. The first ‘Knockout’ roses to show symptoms were located where the highest concentrations of multiflora roses were growing — the East and Midwest. ‘Knockout’ roses in the South have it now too.

Can Anything Stop Rose Rosette?
Because rose rosette is caused by a virus, it eventually spreads internally to every part of the plant. Promptly removing the bright-red shoot clusters by cutting through healthy green wood below them may save a rose. But once a rose gets full-blown rose rosette, turn out the lights. You must pull up the rose, roots and all, bag it, and throw it out with the trash. Spraying will not work.

Conard-Pyle, the respected Pennsylvania nursery that introduced ‘Knockout’ roses, suggests pruning back the plants by 2/3 while they’re dormant in late winter to remove any overwintering mites and eggs in the bud crevices. This is especially important for large landscape plantings of ‘Knockout,’ because the more bushes you have, the more mites you have, and it’s easier for the virus to spread.

Now For Some Really Bad News
According to Grumpy’s sources, most rose species and their selections are vulnerable to rose rosette — not just ‘Knockout.’ So if your love your roses, keep your eyes peeled for weird-looking, bright red shoots. Don’t leave yourself open to a ‘Knockout’ punch.


  1. Steve Bender

    Karen F,

    I have not heard any reports of rosette disease from Canada. That doesn’t mean it couldn’t eventually show up.

    June 14, 2017 at 10:31 am
  2. KarenF

    What if one lives in Ontario, Canada?? Does this disease exist this far north? I live on the outskirts north of Toronto. I have 4 knockouts on me. So far they are looking fairly healthy.

    June 9, 2017 at 11:23 am
  3. Steve Bender


    There could be many reasons for this. It could be spider mites, herbicide damage, or something wrong with the soil. Can you send a photo?

    June 6, 2017 at 10:55 am
  4. Mila

    Just planted five knockout roses and they’re dying, and I do not know what to do they have yellow leaves and the appear that they’re dying I have brown leaves 🍃 Welted

    May 28, 2017 at 7:29 am
  5. Steve Bender

    No. Only roses are affected.

    February 11, 2017 at 8:54 am
  6. Linda

    Are sun patients affected by the resettle disease. I’m thinking about switching to sun patients

    February 8, 2017 at 12:03 pm
  7. Linda

    Are sun patients affected by the rosette. Thinking about changing to sun patients.

    February 8, 2017 at 12:01 pm
  8. Gertrude

    Thanks for sharing your thoughts about the daily south.

    October 31, 2016 at 10:18 pm
  9. Grumpy Gardener

    Now we all do. Thanks.

    July 18, 2016 at 4:17 pm
  10. Frances Horton

    I am absolutely sick about my knockout roses. We live in the mountains near Lake Tahoe. they grow and thrive in many gardens. I planted 10 knockouts in my front garden last summer – they were doing very well. I covered them with pine needles and mulch over the winter – they sprung right back in spring. They were growing well and producing buds. But now the rabbits, chipmunks – whatever (not deer) have totally eaten them up. I put in a fence. I used the anti-rabbit stuff from Home Depot. I used cayenne pepper. I tied ribbons on the fence to scare them away. Nothing works. So I’ll have to take them all out now – and I have no idea where to put them. I potted a few and they’re doing well, but won’t live through the winter because the roots won’t be deep enough. I wish I had known that knockouts were a favorite of rabbits!!

    July 15, 2016 at 10:18 pm
  11. Steve Bender

    The holes are caused by the larvae of a sawfly called a rose slug. It chews away unseen on the bottom of the leaves. Spray your plant according to label directions with neem oil or spinosad. Be sure to wet the bottoms of the leaves.

    July 6, 2016 at 4:34 pm
  12. pam

    My leaves on my knock out roses have little holes all over leaves? What do I need to do? No roses?

    July 3, 2016 at 9:17 pm
  13. Grumpy Gardener

    Jo Ann,

    Rose rosette only affects roses. Some replacements for sun — ‘Limelight’ hydrangea, butterfly bush, rose-of-Sharon, dwarf crepe myrtle, ‘Rose Creek’ glossy abelia.

    June 15, 2016 at 10:21 am
  14. Jo Ann

    Having to take out all my roses due to rosetta. I am considering planting rose of sharon
    as a replacement. Would this be affected by the rosetta. Any other ideas on what to
    replace with that is flowering and take sun?

    June 7, 2016 at 2:38 pm
  15. Kay Roemmich

    Originally I had 18 rose bushes and eight of them were Knockout kind. Six have died and the three Knockout in red bushes are now being dug up. The rose disease has killed my tea roses and bush type as well. I am a trained horticulturalist and florist and this is heart breaking. I have treated these roses with a systemic and sprays when i first noticed the red new growth. Nothing seemed to have worked. I feel this needs to be looked into and put a stop on selling Knockout roses until they are bred to be resist-dent of this mite.

    May 14, 2016 at 2:34 pm
  16. Jill Miller

    I bought mine from Home Depot. They know the problem with their roses in Birmingham. I received a refund for 20 roses i bought from them but it killed the other roses in my yard too. No refund for them. Several people have reported getting them from Home Depot.

    May 7, 2016 at 8:32 pm
  17. Grumpy Gardener



    May 5, 2016 at 2:39 pm
  18. Suzanne Newsom

    Will deer ear Knockout roses? Mine were in full bud and the next thing I knew, it look like someone had cut each bloom off.

    April 30, 2016 at 6:53 pm
  19. Grumpy Gardener


    Roses are grafted onto rootstocks of different roses for hardiness. It sounds to me like the Knockout top part died and the rootstock has taken over.

    April 5, 2016 at 10:05 am
  20. Jeanette Hamilton

    I planted red and pink knockouts six years ago. They are always beautiful. This year one of them is a white double running rose. What caused this to happen. I am baffled.

    April 3, 2016 at 1:36 pm
  21. Mona

    I have this problem thought it might be from moles disturbing the roots of the rose. Disappointed that this is the problem however I know my rose growing days are over. Too much work and money. Let’s say I have been knocked out.

    December 27, 2015 at 1:50 pm
  22. Steve Bender


    No rose is immune as far as I know.

    December 14, 2015 at 4:05 pm
  23. chris Rankin

    Yikes! I’m not sure this is what got ahold of my knockout that is trying to die but I think I’ve seen this on my Chrysler Imperial bush……

    December 9, 2015 at 7:10 pm
  24. james craig

    I live on eastern Long Island. Have had KOR’s for 6 years. Never a problem.

    October 21, 2015 at 10:15 am
  25. PJ Bear

    If you purchase from the big box stores like Home Depot or Lowes..they usually have a one year warranty. Keep the planters and all tags they came with, along with your receipt, and return them within that year for a refund or replacement. Or..just go buy some new roses and take back your old diseased roses, but use the new roses tags and receipt. If they are going to knowingly sell diseased roses then it’s only fair you do a switch on them and get you some healthy ones. I do this because I won’t be cheated out of my hard earned money if I buy something diseased. Fight fire with fire I always say. =)

    September 1, 2015 at 10:42 pm
  26. Michael Herron

    I live in Decatur GA. I planted 30 knockout roses…20 of the got the virus. I had throw them all out.

    September 1, 2015 at 9:21 pm
  27. Steve Bender


    I agree with you 100%.

    August 6, 2015 at 2:15 pm
  28. Stuart

    It should probably be noted that this virus is a ROSE problem not just a Knock Out problem. It effects all roses and the source of it isn’t Knock Out, it’s multiflora rose. The reason people are attributing it so strongly to Knock Out is because those roses are the ones most widely used/planted, so of course you’re going to see the symptoms more often on that variety, because you more frequently see that variety in the landscape.

    August 2, 2015 at 9:49 am
  29. A Better Rose Than Knock Out | Everything Country

    […] Is ‘Knock Out’ Rose Down for the Count? […]

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  30. A Better Rose Than Knock Out | Southern Living Blog

    […] Is ‘Knock Out’ Rose Down for the Count? […]

    July 30, 2015 at 10:00 am
  31. Penny Stuart

    I bought 2 double knockout rosebushes couple of months ago and one of them is doing fine the other one was quite dead think I can do to revive it?

    July 29, 2015 at 3:28 pm
  32. Steve Bender

    Mf Leahy,

    If this is indeed the case, then your state department of agriculture needs to be made aware of it, as selling diseased plants is against the law.

    July 1, 2015 at 10:15 am
  33. Mf leahy

    I was at my local Home Depot garden center in Plano TX this morning and saw that they have “Knockout Roses” for sale that clearly show they are already infected with the Rose Rosette Virus. When I asked if they were aware of it they simply yes we are.. yet the continue to have them on display for sale to a poor unspecting buyer……….. and contributing to the spread of the virus. How irresponsible of Home Depot…

    June 27, 2015 at 12:06 pm
  34. Steve Bender


    I have never heard of raspberries being affected.

    May 30, 2015 at 7:12 am
  35. Steve Bender


    I don’t know of any preventive method that’s been shown to work.

    May 30, 2015 at 7:10 am
  36. Helen

    My neighbor bought a Knockout rose and it had the virus as it began showing signs right away. I asked her to dig it up and she did. The next spring all 15 of my roses, some single and double Knockouts, showed signs of it. Now my raspberry bushes have bright pink stems. I have read that this virus is only on roses but I have some other plants that look odd this year. Have you heard of it being spread to raspberries by using the same clippers or such? I know the mites are rose specific, but perhaps the virus isn’t. Raspberries are closely related to roses, after all. As for the other plants, I am not sure what is going on. I have been gardening for more than 30 years and seeing things I have not seen before. Like plants that don’t get red leaves are getting red leaves and stems. Maybe I am just paranoid. I regret the day I ever saw a Knockout rose.

    May 27, 2015 at 3:30 pm
  37. Rosemary

    Buying new knock out I. Noticed. Ma my
    Frail looking thorns and skim to the flowers is this the start of the disease?
    When the bush is on disease, does this make the soil totally alkaline true or false
    Are there any horticulturist rosarians who would come to my house and let and see for themselves if my knockouts are fully diseased

    May 25, 2015 at 2:14 pm
  38. Deby Wine

    I had ! (ONE!) rose and it died. I had planned to put many around my community, as the HOA President. Would never buy another, ever.

    May 21, 2015 at 2:04 pm
  39. Wilford Lester

    the knockout should not be sold thay are still beingsold ihave planted about 100 i have lost about 10

    May 21, 2015 at 11:58 am

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