Down Chatham Avenue on the island's south end the lanes narrow, the yards run to crushed shell and palmetto, and the afternoon breeze comes straight off the water. South Mowing takes that end of Tybee seriously — mowing, edging, trimming and blow-downs, week in and week out, on lots where a wide turn is a luxury. Grass here answers to salt and sun and moves fast from March to October. The mild winter leaves room for cleanups, cutting back and keeping beds clear. A tight yard cut well reads as generous, and that is the whole trick of it.