First thank you for posting the pic. How much do you water
per day or week?
When it is hotand dry watering at the right time of day in very important so not to burn the foliage. My S x "Indigo Spires" needs watered on a regular basis during our hot & dry summers (37 degree's (C) + for weeks).
When our temps get over 37 (C)watering in the morning is best. I see you have some purslane growing under your Salvia they like it pretty dry.The addition of compost would help with water retention and a bark mulch would help w soil temperatures as well.
It also looks like your Salvia may have picked up
some insects (spider mites possibly). Which maybe the other half of your problem. Look for small red mites
on the undersides of your leaves.
Thanks
Art

Thanks Art! I'll give it all a try - check for mites and watch the water schedule and see how fast I can make new compost (I've just emptied out the bins) but I have some other fert. I can use in the meantime. The other flowers around the salvia all get spot watering, meaning by hand, anyway. And our rains should start within the month!!! Austin is like here probably and so thank you for similar climate knowledge. Will stay around the forum lurking if anything else arises.,..... Batya