Cotton Lavender

Silver foliage does a great deal of work in a hot palette, and Santolina chamaecyparissus supplies it in the neatest possible form: a dense low dome of finely divided, aromatic, felted grey-white leaves that clips into a hard edge.
It is a western Mediterranean plant of dry stony hillsides, so the requirement is sharp drainage and full sun. Humidity and wet feet will kill it far faster than any drought.
Cotton Lavender is the silver edging plant for dry, sharply drained ground, and the only real question is whether the site drains well enough.