Late afternoon on the Walnut Hill side of Natick, the light comes in low and sideways and every lawn shows exactly what was done to it that morning. Diamond Lawns by JP works for that hour — stripes laid true across the slope, edges cut so clean along the walk that the line looks drawn rather than trimmed. Mowing is the steady heartbeat of the season, but the beds get their share too: mulch spread even, borders redefined, the whole yard tightened up in spring and put to bed again once the maples let go. Grass on a hill in this town grows fast in June and stubborn in August, and it takes knowing the difference. Work runs across Natick and out through Wellesley, Needham and Dover.