Late summer in the Nashoba Valley smells of cut grass and ripening apples, and the hills west of Ayer roll off toward Sandy Pond in long green folds. Pinard's Landscaping spends those weeks on lawns — mowing, trimming the ragged margins, hauling off the clippings — until the maples turn and the cleanups begin. Then the season flips to sanders, shovels and a plow blade, working the sloped drives around Pingry Hill where a dusting can turn a hill into a problem. Their measure of a good night is a driveway opened wide and sand down before the light comes. In any month they would rather leave a place tidy than leave it early.