I have an area that gets full sun - not additional water other than rain - and the soil is clay. It is well drained clay, weeds grow very well. I want to plant some ornamental grass that gets 5 feet tall or more. I also want to supplement it with ground cover. I am trying to get the area under control as it gets covered with weeds. I want something that will be attractive and will choke out the weeds. Any advice?