Hempstead Harbor opens north toward the Sound at Glen Cove, and April comes in on that water — cool, bright, and a couple of weeks behind the inland towns. Long Island Tree Service and Lawn Care. starts the season there, cutting back what winter left and getting the mowers out once the ground firms up along the slopes above the harbor. Summer settles into weekly work: mowing, trimming and edging on north shore yards where the land tilts and every lawn has a grade to respect. On a clear evening near Morgan Park you can hear a mower finishing somewhere up the hill, and that is the sound of a street looking after itself. By November it is leaves, and then the ground rests.