First light comes up over the Merrimack River and finds the town still cool under its pines — a good hour to be out with a mower, a trowel, or a plow blade. The Doty Group works these river towns as a landscape and snow outfit: landscape design and construction, weekly and seasonal landscape maintenance, hardscape and masonry — patios, walkways, custom stonework — along with irrigation, outdoor lighting, and snow plowing when the Souhegan runs black between white banks. There is a plain pleasure in the finished thing: a granite walk set true, beds edged clean against the grass, a driveway opened to bare pavement before the first commuter reaches the turnpike. Their reach runs from Merrimack through Nashua, Bedford, Manchester, Amherst, Hudson, Londonderry, Hollis, Milford and Windham, then south across the line to Tyngsborough, Dracut, Lowell, Chelmsford and Andover. A yard that holds its season is a quiet kind of pride, and it is the kind they keep.