Down on Water Street in June the harbor fills with masts, and the lawns along the waterfront have to hold their green against salt and constant sun. Lyons Landscaping, Inc. keeps that going across Plymouth — weekly mowing, trimming into the tight places, borders cut along drives and walks, mulch laid so the beds sit crisp against the turf. The season opens with a cleanup as soon as frost is out of the ground and closes with leaves carted off in the grey end of the year. Between those bookends it is the same steady rotation, week after week, property after property. A yard that never once looks overdue is the entire ambition.