Dear Neil: I xeriscaped my front yard in November 2014 and used the compact form Microburst Texas sage. I’m wondering why one plant died. Its leaves turned a deep gray. Leaves at the bases of the other plants seem brittle and fall off easily with touch. Otherwise, the plants look fine. Can I assume it’s from overwatering? They are on a drip irrigation system.

I would not assume overwatering on a drip irrigation system. In fact, it’s more likely that the one plant, even a Texas sage, was under-watered. Plants that are over-watered lose all their roots at the same time. The entire plant wilts and dies uniformly and leaves usually dry in place and do not shatter. Conversely, plants that get too dry usually start by shedding their lower leaves to lessen the demands being put on their root systems. (Think of how a poinsettia you’ve allowed to dry out drops all its lower leaves and ends up with only the colorful floral bracts at the tops of its stems.)

Check to be sure that the one plant’s emitter or emitters are functioning correctly and that they aren’t plugged or that they haven’t been chewed by a rodent or pulled loose during maintenance. Texas sage plants have been hurt by winter cold several of the recent winters in colder parts of the state. And yes, it could impact one plant out of several if that one plant had been weakened for one reason or another. Texas sages are susceptible, for example, to damage of lace bugs and subsequent development of sooty mold fungus. I don’t see that in your photos, but it’s something to watch for.