Down along the Salmon Falls the old pines of Vaughan Woods keep the river cool, and the lawns on the roads above green up early and hold their color into October. Chase Brothers LLC works that long season — mowing on a weekly rhythm, trimming around trees, granite steps and stone walls, edging drives so the lines stay honest. Spring opens with a cleanup that clears winter sand and dead thatch out of the turf; autumn closes with leaves gathered and gone before the rain glues them to the grass. A South Berwick yard in June, cut and edged with river light coming through the trees, is about as good as summer work gets. Keeping it that way, week to week, is the craft of it.