Is this happening on all your salvias or just one plant? What type of salvia do you have? Perhaps you're killing them with kindness. Salvias tend to like it leaner/drier than other plants. I will say they're generally pretty resilient and when I've had ones that were struggling I cut them back hard and they generally rebound.
Thank You Doug for the information..We have 2 raised beds and they are dying in the one bed but really thriving in the other but I think the one they are dying in is the bed that gets more rain than the other one. I will try cutting them back to see if they come back. They are salvia divinorum plants. Thanks again!!!