Holtsville sits on the flat pine plain in the middle of Brookhaven, where the ecology preserve's gardens hold their green straight through August. Emerald Magic Lawn Care mows, trims and edges through that heat, when a Long Island lawn either gets attention or goes tan by the second week of July. Fertilizing and overseeding put color back into thinned turf, and mulch keeps the beds from baking. Spring and fall cleanups deal with the pine needles and oak leaves that come down along every street here. A deep green yard on a hot flat afternoon is a small act of stubbornness, and that is exactly the point.