Up on the bluff at Tower Road, Lake Michigan sends a cool wind inland that keeps Winnetka lawns heavy with dew until mid-morning, long after the rest of the county has dried. Van Zelst Inc. plans the day around that — the lakeside blocks later, the inland streets first, so every cut lands on grass that is ready for it. The work itself is steady and specific: mowing, trimming, clean edges along walks, drives and beds, and the cleanups that open and close the season. A lawn near the water holds its green late into the fall if it is kept on schedule, and that long green is the thing worth chasing. Winnetka, with Glencoe, Kenilworth, Wilmette and Northfield nearby.