No, under those conditions it should actually help to control disease.

Thanks Michael, I was holding my breath that someone would not answer that I had to w*ater by hand. You just made my day. [g]

Unless I am mistaken, God waters everything from overhead. If His water doesn't affect you roses, then any watering you do from overhead will be fine. I'm sure you like a cool shower on a warm day, right? Well, your roses will appreciate the refreshment too.

I've always thought that roseman, but....sometimes I think watering with public water from the faucet and rain are different. One summer we had rain at all the right times and barely had to use the sprinkler at all that year. I had noticably fewer foliage problems that year. Of course, it's just a theory but, you never know what is in the water these days and from the smell of it, plenty of chlorine which couldn't be good.

I'm sure we'd all rather rain but have to water when you don't get it.

Thanks!

The only problem with overhead watering is if the leaves dont have time to dry. Fungus spores take anywhere from 3hrs to 9hrs after landing on the leaves to attach and grow and they need to be wet the entire time. So go ahead and turn the sprinklers on, just be sure the leaves dry off quickly.
Sedgewick

I have well water with no chemicals added and have been overhead watering for over 20 years. I don't spray pesticides of any kind. My roses do get some blackspot when disease pressure is high but no more than those of growers who spray. The theory is that the overhead watering keeps blackspot spores washed off the leaves. Watering early allows the leaves to dry off. My watering system starts up at 4:00 A.M. By noon all the plants have dry foliage. You can buy inexpensive faucet timers that will turn your sprinkler on before you wake up.

Rain water contains water soluble natural nitrogen which is why rain is best for your garden. This explains why, after a summer storm, your roses will look better. Untreated well water is closest to rain. When I lived in an urban area, I put in a well to avoid using city water and cut down on my water bill. This also allowed me to have a green lawn and garden when watering restrictions were in place.
When you water, let it run long enough to get down to the deep roots. Surface watering causes the feeder roots to stay close to the surface. During periods of little or no rain, surface watered plants will show early signs of stress.

I use well-water also, and have overhead sprinklers, I run each zone ( 2 zones for the roses) for 1 hour starting at 3 AM and ending at 5 AM...... the sun comes up here now abt. 6:30, I don't run them any later because the paper comes abt. 5:30 - 6 AM and I like a dry paper in the morning...... sally

Karl's last paragraph is important. Frequently sprinklers do not water long enough to go deep enough and so the roots stay on the surface which makes them more demanding of water because of evaportation and also does not allow the roses the deep roots it needs to hjold the plant. Rule of thumb, one inch of water penetrates four inches of soil. If your roots are 12 inches deep, you need three inches of water. If you live in a dry climate where evaporation occurs quickly, you should probably hand water/deep water every other week or so, especially young plants.

All of the above.

I spray my roses w/ fungicides regularly and a very occasional insecticide if I see damage. I have been overhead watering for the past few years on sunny days.

Such overhead watering appears to keep our roses less stressed and healthier. I had spider mite problems about five years ago, and started overhead watering on hot summer sunny days to combat spider mites. I expanded that program to include any sunny day that I have time to water on.

We still water at the surface too so as to keep the roots well-watered.

Just a short reprise - Yes, it is great to have rain for the roses, but remember there are certain contaminants in the air it falls through. It's nice to have a well too. However, if you can't have a well, you have to make do with what you have. Because of the chlorine, flourine, and feldspar from the city wells, I had a whole-house water filter system installed, and that solved a lot of problems in and out of the garden. I know that not everyone is able to do that, and many of my friends have to depend on city water as it is, but their roses haven't suffered all that much. It's just not a perfect world that's all.

The problem with overhead watering is that you waste 80 percent of the water and most of the the remaining ten percent that falls on the ground where the roots are doesn't get to the roots. You need an under ground watering system and the easiest, most reliable, least expensive, most trouble-free and most efficient system is the soaker hose.

Henry,
Only if you don't water long enough. I placed the flat tuna cans in my yard where I watered and turned on the sprinkling system. When the last can was full, about an inch of water, I knew I'd watered enough. It takes about an hour to fill the last can so my zones are set to run an hour in each of 8 zones.
80% and 10% only add up to 90% but even with that, I wonder where you got those facts? If you're referring to all the water that doesn't actually fall in the rose beds but falls elsewhere, like on the lawn, it's not wasted it's used elsewhere. My lawn is almost as important to me as my roses so I don't consider any of the water wasted. Yes, I have an underground watering system but well placed hose sprinklers run long enough will do as good a job, It's just more difficult and time consuming.
At my old home I put in my own system. I ran one inch PVC pipes down the middle of each bed. Dramm nozzels were placed every four feet. All the water was contained in the beds. Before I ran pressure lines to the pipes, I used quick connect fittings on each pipe and moved hoses to water. I quickly tired of that and ran pressure lines with remote valves on a timer. It took me a couple of years to perfect it but eventually, watering was done with little work on my part. I eventually expanded the system to water the lawn and that's when I found out that overhead watering could help prevent blackspot if done early enough in the day so the leaves could dry.
Here I didn't worry about watering overhead on the roses or bother to run lines only in the beds.
I get some blackspot but usually when disease pressure is highest and everyone, even those who spray fungicides, end up with it.

Karl, yes 10 and 80 do equal 90...I should have said 20 percent of the water lands on the ground over the roots. It depends on your garden but here is the reasoning. First, 20 percent is a generous estimate of the percent of the total area in the garden where airborn water will end up landing where it is needed. There is all that open space plus all the area around the outside, Second, Much of the water will fall on the roses and never reach the ground because they are so thick they protect the ground from the water. Even a moderately heavy rain like we had last night will leave the ground only slightly moist under the heavy coverage of the roses which are filled with water, And then there is the thick mulch that the water must get through. The water is soaked up like a sponge long before it gets down to the roots which are deep or at least they should be. Finally, I almost never water because rich organic soil down three feet with heavy mulch stays moist. I check it and with normal rainfall here it has stayed moist all through the summer the last two years so I have really not needed to use my watering system at all. This year it has been dryer so I have watered some even though the subsurface soil has remained moist. Finally, there is the question of water conservation. I always worry about my well so I don't waste water. In my garden nearly all the water used gets directly to the roots.