North Billerica keeps its brick, the mill walls and the old blocks down by the falls, and the grass in front of them stays green well into late September. Munoz Landscaping Corporation looks after those lawns and the ones on the streets climbing away from the river, mowing, trimming, edging, tending mulch and beds, and cleaning the yards down twice a year. Small mill-village lots and long suburban ones need the same thing in the end, which is somebody who finishes the edges instead of just crossing the middle. September cuts are the most satisfying of all, cool air, slower growth, and a lawn that holds its shape for a full week. Grass level, beds defined, walkways clear, and the whole block looking a shade sharper for it.