Where do you live that Knockouts get tons of Blackspot? Just wondering... You did not need to cut it down... The blackspotted leaves would of fell off the bush and new leaves would of taken there place...

The bushes should grow back...

Blackspot spores are always in our gardens no matter what we do...

Knockouts here are extremely disease resistant. A couple of months ago a company sprayed a herbicide that covered by knockout roses. I trimmed them back to about 10". They are now growing again and have some new basal breaks and stems coming from the older wood there where I trimmed them. I kept them moist, not wet for several weeks until they started leafing out again. Knockouts are very resilient so they should come back with some extra watering care.

I will admit I have 1 KO. Purchased 16 yrs. ago, after learning of its parentage . Back then, I didn't know what was to come.

Once it became clear 3x3 feet was a myth, I began to cut it down to the ground each spring. Around May 1, on average . Here, in NJ. It didn't do quite as well when I did. But I continued the practice. Conceivably by an unconscious desire to do it in.

I stopped that practice more recently, after reports of its various afflictions surfaced.

Thank you everyone for answering. I'm at zone 5a in New York, when I said I cut it to the ground, I mean it's virtually unseen now with probably 1/3 inch of stem above the soil if u pay very close attention. Btw, it was planted about 2 weeks ago. I know I should have been more conservative at the treatment :( do you still think there is a chance it might live?

I was confused though, isn't black spot only affecting the leaves? Is it normal that the branches also had that many spots on them?

I just watered it thoroughly for the day. I haven't fertilized it yet as its newly planted. Now it's in the ground consisting of natural soil, garden soil I bought and compost.

Start at the beginning. You bought it two weeks ago. Was it a potted, growing plant, or a bareroot? When did the spots first appear? Have you sprayed it with anything other than water?

No, you haven't killed it. At least not this year. However, I also seriously doubt it has blackspot. So the question is what does it have, how serious is it, and what, if anything, should be done about it.

BTW, Knock Out isn't really a zone 5 rose. It is much happier in zone 6, and can die off in a winter where the temperature goes below -15F.

I also think it was not black spot. But they sure can get spot anthracnose which can also infect the canes. Have you have been suffering the horrible cool, cloudy and drippy weather that many of us have. Bacterial spot or anthracnose is a good bet. We had this darn weather here last year and it went on forever. I saw anthracnose on nearly everything here. Anthracnose will spot the leaves but the leaves don't yellow and fall from the bush like black spot does. It's ugly thou. Some of my roses had it bad enough that the canes spotted as well. I'm not sure what happened to many of the roses being sold this year but I've seen a lot of spotted canes out there.

Back to your rose I think it well come back fine for you. If possible pick up any debris left by what you cut. I would also gently dab bleach on any spots that may be on the bottom few inches of cane. So that it will not reinfect the bush and pray for better weather.

Patty - if you Leslie's response above, there are not a "bottom few inches of cane" left - there is only 1/3rd of an inch. I would not paint that with bleach - I would leave it alone. I was concerned she may have cut off all of the scion, if the bush is grafted onto other roots - that's why I asked.

Jackie

I have never seen knockouts get diseased, however if they were I wouldn't expect them to live. I always drastically cut back my roses in the winter but not to the ground

Yes Patty, 1/3 inch :(

After viewing all the online pictures and videos the symptoms are aligned with the black spot disease....at the beginning some leaves showed tiny black dots, which later expanded and before I cut the bush, the spots have become bigger with yellow circle around and extended to not only more leaves, but also the branches and canes. Leaves also fell, and flowers all had a depressed look and petals were very fragile to lose. Before they were planted, I had them in pots for a week and left them outside. We had a series of rains for a few days.

Normally Knockout roses are very blackspot resistant in most areas but maybe your rose bush was stressed for some reason?

Blackspot and Anthracnose disease are somewhat similar....

BLACKSPOT:

Anthracnose

Given the weather, the first thing I thought of was they were sprayed and then frozen. That produces small black spots, and can cause defoliation. This would have been something that happened before they were purchased. I'm still not willing to rule that out because of the timing. It was COLD here three weeks ago, and that is something to definitely keep in mind when trying to diagnose this problem. The established Knock Outs probably had no leaves yet when this rose was planted.

i'm glad someone did this and not me yet. i want to cut mine to 6" above the ground. it has grown to over 6' tall and 4' wide. it has three canes coming out of the ground that are more than the circumference of a silver dollar and no green for the first 2.5' to 3'. it looks like a tree and it's very unattractive at the bottom. if i don't cut it down i'll have to pull it because i can't see over or around it from my porch.

Hi butterflywing

It sounds like you have two issues with your (presumably) Knockouts that are a little different than the OP's - how high off the ground the branches start, and how big the bush gets. There may be some strategies to help with at least one of these issues, but depending on where you live it's hard to make too drastic a change in how big a rose wants to get. It would help us to let us know your region of the country and we can give you more specific advice.

For the first issue of how high the branches start, it's possible that trimming it down to 6" might encourage it to branch out a little lower, but for some roses it might not. I routinely have to prune most of my roses to the ground or nearly there most years, and some roses simply want to get big on one cane before they start branching out. Other times, you can get branching out like a candelabra from wherever you last pruned it, and you definitely want to prune those kinds of roses low at first so the candelabra isn't far off the ground. In my experience, Knockout isn't a particularly prone rose for doing the candelabra thing, but branches more or less where it wants to. In your zone, it may act different than in mine - it's sometimes hard to generalize about a given type of rose.

As for its ultimate height, it sounds like even if it branched out lower it wouldn't fit where you have it if it still gets to 6' high and 4' wide. That's something I'd frankly like to see in my knockouts, so I expect you're in a warmer zone than mine. I find that I can encourage a rose to be maybe a foot or so lower than it really wants to be with diligent pruning, but if it really wants to be 6' in your zone it's not going to stay happily at 3'.

Given that you say it's not acceptable as it is in that spot, I don't see a problem with trying to prune it low, perhaps as low as 6' off the ground. It will definitely reduce its blooms for quite a while as it recovers the canes, and it might sulk and return to its old habits. If it's a choice between digging it out entirely or giving it a chance to "shape up", I'd opt for giving a try. Just realize that if it keeps stretching back to 6' it isn't necessarily something you did or didn't do, just how the rose is fitting in to your conditions. At that point, you may want to log in with a new thread here and see what kind of rose might stay at a better size for you in your zone.

Hope that helps

Cynthia

it 's a KO about 5 years old. the old wood has a dark bark. i live in central NJ. i just checked on it to make sure i have this right. yesterday in a frenzy, i lopped off about 2.5', blooms and all. it's still over 5' tall. you'd never know they were gone. the bottom is naked until about 2.5' up.then it begins to green up half-heartedly, and then it literally explodes with greenery and blooms. it's a tangled thicket that i can't see through. the canes are growing out of a large round - it must be a graft which has grown itself out of the ground. you can tell i'm rose challenged. i'd like to cut it down if possible and start over the right way. can i do that?

In our area it is not uncommon at all to see KOs that are 6 ft tall with no leaves on the bottom 1.5' of the rose. They are bare from the ground up for 1-2 feet. I've observed them being pruned back down to 3.5' in February and by late June are again 6' tall. If they are heavily pruned from the time they go in the ground they can be kept as 4 ft shrubs. I prune mine back to 18" in February and by June they are 3 feet tall. By pruning them back that short they do throw basal breaks and keep leaves on the bottom of the shrub. They do develop a lot of large canes at the ground and will develop a knot of wood.

i see you live in texas. i live in central nj, 5-6. i'd like to keep them at 3' to 4' and a little less wide wide. that was why i bought them. silly me. so i was thinking maybe cutting back 6" but maybe 12"? in february?

My rose bush is covered with scale. Cutting off at the ground has been recommended by an expert. Is it ok to do it in 90 degree weather ? Other rememdies have seemed too labor intensive.