It seems like the groundcovers that are not succulent in nature have a really hard time doing well with limited water. I'm guessing it is because they usually have very shallow roots. Convolvulus sabatius (Ground Morning Glory) is an exception. It is really more like a very short shrub, growing about three feet wide, along the ground, and I'm assuming it has deeper roots because of this. You buy it in one gallon containers and it doesn't naturally root, reseed or send out runners (unlike crazy vine morning glories) so maybe it isn't really considered a ground cover, more like a ground hugger! I do love the color and the easy growing nature of this charming plant, blooms all year round and drought tolerant too! You couldn't ask for more!