Emerson Garden sits behind its low wall off Davis Avenue, a quiet green room in the middle of Brookline, and September light makes it glow at about five in the afternoon. Rose Lawn Care Services keeps the neighborhood's own patches of grass in that condition — mown, trimmed, edged, and cleared once the leaves begin letting go. Late-season turf is the finest turf in New England: cool nights, soft rain, and color that finally holds. It is the right stretch of the year to overseed thin ground and send a lawn into winter thick. A yard that goes to sleep well wakes up well, and that is the long game here.