We recently purchased a beautiful 1940 Georgian Colonial with 5 acres of lovely estate-type manicured yard and gardens. I have one problem, however (aside from the high maintenance of course) and that is one large area of the lawn. In this area, we have exposure to the hot summer sun, although we do have a sprinkler system. The grass does not do that well in the sun as it is St Augustine. I was hoping to plant some hedges in that area, much like the maze-like hedges you might see in larger English gardens. Does anyone have any suggestions on what plant might be best for this use, considering the climate down here...hot and humid in summer, but can have cold snaps in winter.

Thanks so much for your suggestions and opinions!!