From Crocker Park in July you can watch a hundred hulls swing on their moorings, and the lawns above the harbor have to hold their own against sun, salt and shallow soil. Martin Landscape Services keeps them doing it — weekly mowing, string trimming, sharp edges along walks and drives, and feeding and overseeding right through the growing months. Beds get weeded and mulched, and cleanups bookend the calendar at either end of the year. There's a particular stillness at the end of a cut lawn on a hot afternoon, everything squared away and the water just past the fence line. Marblehead grass, taken seriously.