Kenvil sits on flat ground with a long industrial past behind it, and the lawns there take the July sun straight on with nothing to hide behind. GreenMax Lawn Care handles them week to week — mowing, string trimming, edging along drives and walks, and the spring and fall cleanups on either end. Heat like that thins a lawn fast, so a regular schedule and an even cut do more good than anything dramatic. There is a plain satisfaction in the sound of the mower shutting off and a yard standing there finished. Across Roxbury the same routine repeats, house by house, right through the season.