Check the PH of your soil and the water you most commonly feed the safe plants ASAP. Sounds like the soil might be too alkaline for the sage plants. When the PH is too high (alkaline) like your's may be, it will generally stunt the growth of plants completely and cause leaves to turn brown and fall off. Happened to several species in my garden after I moved into my new house. I discovered we had hard water (high levels of calcium, lime and other dissolved minerals that cause alkalinity in the water and subsequently the soil) and so now I only feed my plants collected rainwater through two 65 gallon food safe barrels I purchased for $45 a piece. They are fed by bypass lines on my home's gutter downspouts which were under $30 and easy to install with a saw and a screwdriver. Using rainwater has saved my garden and my money.
Check the PH of your soil and the water you most commonly feed the safe plants ASAP. Sounds like the soil might be too alkaline for the sage plants. When the PH is too high (alkaline) like your's may be, it will generally stunt the growth of plants completely and cause leaves to turn brown and fall off. Happened to several species in my garden after I moved into my new house. I discovered we had hard water (high levels of calcium, lime and other dissolved minerals that cause alkalinity in the water and subsequently the soil) and so now I only feed my plants collected rainwater through two 65 gallon food safe barrels I purchased for $45 a piece. They are fed by bypass lines on my home's gutter downspouts which were under $30 and easy to install with a saw and a screwdriver. Using rainwater has saved my garden and my money.