Before dawn on a storm day, Route 21 through Ludlow is nothing but headlights and blowing white, and the driveways off it are waiting. Pine Hill Landscaping LLC is out in it — plowing, shoveling walks and steps, spreading sand and salt so the first trip of the morning turns out uneventful. When Broad Brook runs high with melt and the ground finally firms, those same yards move onto the mowing list: cut, trimmed, edged, and cleaned up spring and fall. Ludlow's hills put sun on one side of a street and shade on the other, so no two lawns run on quite the same schedule. Paying attention to that difference is most of the job.