A lawn cut clean, its edge run tight along the walk, holds that line for days — and that is the mark Winslow Landscaping leaves on the yards of Derby. Mowing here means working ground that tilts toward water, in the small valley city where the Naugatuck slips into the Housatonic and the old brick mill blocks catch the late afternoon light. Grass is kept through the long green stretch of summer and the slow gold slide toward October, across terraced side-yards that step down toward Route 34 and the level lots tucked in behind Main Street. It is plain, physical care, and it shows: a yard that looks looked-after, a lawn worth walking out onto barefoot after supper.