This picture shows two typical problems found in many designs, first, and perhaps most obvious, is the widely spaced bunch grass clumps with open mulched ground that will always be susceptible to weed invasion requiring much manual control and/or the use of herbicides, commonly both post and pre-emergence types. The other issue is single species ground cover masses, essentially monocultures, that are subject to invasion by certain weed species that vary with the ground cover. Successful ground covers have been increasingly demonstrated to be mixes of complementary species that work in association with one another to fill available niches. Single species are more subject to failure as there ability to compete with weeds is narrow. They are also more likely to result in thin or bald spots. Highly successful single species ground covers are themselves border line invasive and can act as ‘thugs’ in the landscape crowding out desirable plants.