Answer: Roses, like most shrubs, prefer a good soaking followed by a dry period before another soaking. This allows the water to move down into the soil profile, pulling air with it as it goes. The length of the dry period varies with soil type, soil depth, temperature, sun vs. shade or overcast, container grown vs. planted in soil, etc.
In your location, once or twice a week watering will probably be sufficient depending on the temperatures and amount of direct sun. However, in very sandy soil with no organic matter added, you may have to water more often. Container plants need a daily watering.
If your plants get a bit too dry for too long, or too wet for too long, they will start to exhibit yellow older leaves which drop from the plant.
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