I recently planted several purple Salvia plants that have completely faded from beautiful, bright purple to beige. It has been really hot and dry and I’ve been watering them in clay soil once to twice a day. Is it possible that I’m overwatering them? Or do they need even more water since they were just planted?
I’m not sure what type of Salvia you are growing, but it is possible you are overwatering them. The heavy clay soil combined with watering 1-2 times daily sounds like too much for a plant that is drought-tolerant once established. To learn more about growing ornamental salvias, see this University of California, Davis Arboretum Review, #44, Fall 2003 article, “Salvias for Every Garden” by Ellen Zagory.
I would suggest watering less often, but watering more deeply, and possibly mulching around the plants. Some xeriscaping resources suggest using gravel, and it is mentioned in “Landscape Water Conservation: Principles of Xeriscape” from New Mexico State University Extension, with the caution that although “some plants native to very well drained soils grow better in gravel mulches […] rock mulch becomes very hot in our climate and can injure or limit growth of some plants. Ultimately, the mulch should be shaded by landscape plants that will provide environmental cooling. Using gravel mulch alone as a landscape element may result in increased home cooling bills and require greater weed control efforts.”
This article by Seattle-area garden writer Ann Lovejoy on drought-tolerant gardening may also be of interest.