Anyone have any suggestions for a sandy, weedy back yard? The soil is extremely sandy; the top layer is almost like dust. Seeded grass sprouts just fine but doesn't survive the summer heat. And it's a rather large area I can't afford to water all summer. The kids play on it alot, so I can't rope it off, bring in new soil, etc. I was thinking of trying some native grasses perhaps, like Buffalo grass or something. Any thoughts?