North Walpole sits on a shelf above the falls, its streets short and its lawns shorter, squeezed in between the sidewalk and the porch rail. MTN Landscaping cuts them on the week — mowing, trimming around the granite and the fence line, the edge cut back to the concrete. April brings the cleanup of road grit and broken twigs; autumn brings the leaves off the big street maples. Small yards reward precision, because there is nowhere for a sloppy pass to hide. Done right, a whole block of them reads like one long green ribbon.