Lake Bluff green is a shaded green — ravines cutting down toward the lake, old oaks holding most of the light overhead, and the turf below making the most of whatever falls through. Green Concepts Inc. keeps that grass honest all summer: mowing on a steady rotation, trimming close along fence lines and foundations, edging walks so the border between lawn and concrete is a clean one. Late June, after a warm rain, a yard on these streets can look almost lit from the inside, and that is the afternoon the work pays for itself. Autumn turns the job over to leaves, and there are a great many of them under a canopy like this. Lawn care for Lake Bluff and the North Shore blocks around it, yard by yard, week by week.