Deann: grass/lawn is the ultimate ground cover. It's obviously high maintenance. Contractors/builders often flip-flop the soil so that the clay is on top. Soil amendment is key in most plants and the most important element in having a lush lawn. Sand and/or quarry limestone grit mixed into the clay allows roots to go deeper, more quickly. Fescues can have their roots three to three and a half feet deep. Also fescues fare better in shady areas than other grasses.
Organic fertilizers are the ONLY ones that should be used on a lawn. The reason is not so obvious. Chemical-based fertilizers will "green up" a lawn quickly, but at a high price. The grass roots stay on the surface, instead of going down. This will cause thatch which eventually kill parts of the lawn. Once a properly planned lawn is in place, it will withstand the hottest and most arid conditions.
BTW, as to only native plants, you'll miss out on Helleborus niger (even though it likes its moisture). Now go get some soil on your knees.
"When in doubt, empty the clip."
