I've stopped watering mine now. I spot water some of the annuals and the ones in pots but the perennials have stopped actively growing. This is the usual time for me to stop watering everything, especially the grass. The leaves are changing color and that is my sign to stop.
If they aren't turning to Fall colors and still blooming keep watering.
Several reasons... good for the plants and VERY helpful to the insects and birds.
Butterflies, Bees, etc are rapidly running out of food sources.
Any blooming plants are a plus.
Please join us at the Ohio River Valley Gardening Forum here at Dave's.