Follow the Hennepin Canal east of Annawan and the towpath runs straight as a rule line between the trees, the water still, the Green River country flat and black-soiled on both sides. Johnson Landscaping Services works the yards of that town — mowing, trimming, edging, spring and fall cleanups — where the lots are broad and the wind off the fields never quite stops. Summer here grows grass in a hurry; a warm rain on Tuesday makes a Thursday that needs the whole afternoon. The good part comes at the end of it: a yard clipped even, the clippings swept off the drive, a straight seam where the turf stops and the concrete starts.