buy a moisture meter. It has a thingie on top for reading and a prong with a sensor on the end that you stick in the soil. Like a meat thermometer, only bigger...and for dirt.
Saves going all obsessive compulsive over it. ;-)

Thanks for all the answers,and infro!

Rule of thumb 1" of water penetrates 4" of soil. Sandy soil is more, clay is less. If your rose has roots 10" deep, you want to put on about 3" of water, once or twice a week depending on temperature, rain, humidity. Sprinklers are the most inefficient way to water anything but grass, plus damps leaves are conducive to mildew. And my grandfather always said, "Roses don't like to go to bed with their feet wet. So, water with a hose early in the morning.

To determine how much water my roses were getting with my watering system, I placed flat tuna or cat food cans at each bush. When the last one was full I knew each rose had at least an inch of water.
My system incorporates the gear driven sprinkler heads and waters from overhead. Those heads in a rose bed are mounted on pipes standing three feet above the ground so the spray clears the bushes and doesn't beat one or two to death.
The first zone begins watering at 4:00 a.m. Each zone is watered for one hour and all is done by noon. Everything is dry by 1:00 p.m. I'm fortunate to have sand so drainage or overwatering is not a problem.
I used the same tuna/cat food can method with a drip system at my old house. I placed a can under each dripper. When the last one was full, they all had an inch of water or more.
I'm also fortunate to have a good well with a large submersible pump that supplies a lot of pressure. My house and watering system use the same well and I don't lose any pressure when the system is on. When installing the pump, I opted for a one horsepower instead of a half horse. It was well worth the few extra $$. I also had frost proof hydrants installed with the well, so I have water available way out in the yard and also in my greenhouse.
Because of my sandy soil, I water every day in hot dry weather and every other day in cooler weather.
I put a lot of thought into my system and tried not to make the same mistakes I made with the system at my old house.

I second the tuna can method of seeing how much water you are putting down. It completely eliminates the guesswork factor. I water with an oscillating sprinkler 3 hours at a time twice a week in the middle of hot and dry July and August. However, as others have pointed out, soil makeup can really affect whether you should water more or less, as can water pressure within your system. I live in the country on rural water, and our pressure is pretty low - hence my long watering times.

I would say that yellowing leaves are a sign of too much water, not enough. Or possibly just old leaves dying off of old age, or fungus infection. The best signal that the roses are not getting enough water is wilting of the buds and new growth at the top.

Karl,thank you for the advice on the tuna can.I knew I could count on you.Wish I lived close to Indiana,I would love to meet you,and see your gardens.

rose nutty,I live in the country,and have rural water.OMG my bill is like $130 a month.One of my KO,the whole bush turned yellow.I pruned it back,and there is new growth on it.

Ann

Ours is expensive, too. $150 a month is not unusual in the summer months for us. Coulda drilled a well and probably paid for it by now, if only we'd have known how expensive it would be . . .