I don't and I won't. I use drip and hand watering at the base and I avoid getting the leaves wet. Overhead might work in the desert, but with our humidity my guess is it would just make matters worse because the plant never dries out.

I do in NW Indiana and it's quite successful for me. My watering begins at 4:00 a.m. and is done by 11:00 at one hour in each of 7 zones. On normal sunny days, all my roses are dry by 1 p.m. I water every other day unless it rains. I start this practice as soon as I turn on my watering system in the spring and continue the practice until the system is shut down in late fall, not just during periods of drought when the lawn needs watering. Once blackspot gets a foot hold, only spraying fungicides will control it.
During the last month of hot humid weather, I did get blackspot. I don't have a perfect leaf phobia nor do I exhibit so I don't get all excited about it.
Like s**t, blackspot happens in no spray gardens

Like so many things in rose gardening, it's a matter of location. I water overhead in the evenings so that the water has time to sink in during the cool of the night. If I watered in the morning the sun would dry off the water on the plants and ground, and much of the water would be wasted. Of course, we have very little blackspot.

I have overhead and have 2 zones, set to come on 3AM and 4 AM, one hour each.. they finish before dawn and the roses dry off when the sun comes up, abt. 7:15 now....I usually set it for every other night, unless we get rain, it is on manual........ I have some BS , but do not spray, everything is organic...... some roses get BS worse than others, some get none at all.... I'm gradually replacing the ones that get BS with resistant varieties..... I like the overhead because it waters everything, all my perennial beds as well as the grass... and is very easy to repair if something breaks........ works for me.......sally

Paul Zimmerman also does over head watering for BS.
I provided the link below.

I think it depends on where you live and garden, whether it helps or hinders.
I've never personally tried it to comment. I'm too chicken #*^@! LOL

Here is a link that might be useful: Over-head watering (PZ)

I have my roses on drip, but after reading the article "A daily bath" by a rose gardener in CA, I began hosing my roses down every couple days. I actually spray them as hard as they can handle, so as to discourage spider mites. I usually do it in the later afternoon, so the leaves aren't wet for long. I don't know if this practice has helped, but it certainly hasn't hurt. Actually, this year I haven't hosed them down more than a couple times, and the roses have been the most fungified I've ever seen them; so maybe it does help.

Of course, I get away with this sort of obsessive behavior because I only have about 25 roses.

Best,
Lara

There is nothing wrong with overhead watering as long as you also have and practice a solid spray regimen. The idea that the water will wash away the BS spores is specious at best. BS is a soil bourne fungus that depends on moisture for its existence. If you spray every 7 to ten days with a recommended formula, and if you allow the spray to dry on the foliage before watering, you should have no trouble keeping the baddies away. I have watered my roses with every method known to man for over thirty years with no problems mainly because I have a solid spray program and follow it to the letter.

I have never heard anyone claim that overhead watering would eliminate blackspot. There is evidence that it can reduce blackspot. The spores are sticky, and obviously you are not going to wash off all of them. In Florida's rainy season, they get 2-4" a week in the form of heavy thundershowers, and there is still some blackspot.

The theory is, that since the blackspot spores need to sit on the leaves, in water, for I think 7 hours to germinate, that a good washing off will remove them before they can germinate. It's possible that your watering system just didn't wash the leaves thoroughly enough. I believe it's the spores on the undersides of the leaves that cause the trouble, not so much the spores that landed on the tops. So you'd have to wash the undersides of the leaves.

I've known people to do this successfully for powdery mildew, in California, handwashing the roses with a hose not a sprinkler, but not so much for blackspot. PM wants high humidity but a dry leaf to germinate, where blackspot needs actual liquid water to germinate. But as you can see from other posters, it works for them on blackspot.

What works best for me is growing only rose varieties that resist the fungal diseases common to my area.

I have given the ones that didn't work out to folks in more suitable micro-climates, and have gotten to the point where things look pretty good with no spraying at all.

My routine is very similar to petaloids practices.
I keep the BS resistant roses without spraying and rid the garden of the weaker offenders.
I do not grow anywhere near the number of roses most other forum members do. So, it hasn't been that bad to accomplish here so far. Every years a new experience though. lol

I agree that it totally depends on your local climate and type of soil, etc. If you look on Vintage Gardens (located in No Cal) website, you will see that they overhead water, but with a tremendous amount of water, only once every two weeks or so. They are in a nice warm, dry climate, and have very sandy soil, and are located on a hill.

I can understand why it would not work in a humid climate - if the leaves do not dry out within the 7 hours it takes blackspot spores to germinate, that would explain it.

My mother-in-laws garden near here had an extensive overhead watering system for the large rose garden, and her mostly HT roses were almost free of blackspot and mildew, without any spraying.

Jackie

When we get regular rain, which would be close to overhead watering, and that's usually when I get the worst black spot. I do have many spots in my yard that don't get enough AM sun to dry off the leaves. But I don't have a sprinkler system, so I wouldn't be watering at 3am anyway. The only time I over head water is in the spring to get rid of aphids. I do have to water tomorrow because we haven't had rain in about 2 weeks and everything is drying up. But I'll probably just water the roots.

Lainey2, don't know about Virginia (well, I can guess), but I wouldn't have even tried it here in humid Kansas. Washing may help spider mites, but it will only exacerbate blackspot sooner or later.

Here is a link that might be useful: Garden Musings

I get blackspot no matter if I overhead water or don't, and there is not a rose out there that does not get blackspot here, including knockouts!

Petaloid, Do you get BS living in So. Cal? I know you probably get PM but what other fungal diseases do you get?

Ramblinrose, in my area I don't often see the true blackspot that is problematic in other climates.

Here we have to watch out for spot anthracnose (which makes a different kind of black spot) and powdery mildew. Because I am near the coast, I need to avoid anything that gets rose rust fungus.

We also see downy mildew and botrytis during rainy spells, but I don't think varietal selection matters with those.