From the lawn at Larz Anderson Park the Boston skyline stands up over the treetops, and by October the hill below it goes the color of a struck match. GC Brookline Landscaping Services spends that stretch of the calendar in the leaves — blowing, raking, hauling, and cutting one last time before the ground goes hard. The rest of the year runs on the steady rhythm of mowing and edging, the kind of upkeep nobody notices until it stops. Brookline's yards are terraced and tucked between old walls, so the mower comes off the truck and the hands finish the corners. The payoff is a clean sweep of green under a big sky, week after week.