April on the Esplanade is all wind and new leaf, and behind the brick fronts up the hill the lawns are only just waking. The Boston Landscaping Company handles the year's opening — clearing winter grit, that careful first cut, feeding and overseeding wherever salt burned the edges. After that the calendar takes over: mowing, trimming, edging along granite, mulching, and leaves cleared out before December. Working in the oldest parts of the city means narrow gates, tight corners and yards measured in steps. A hand-finished edge in a place like that is worth the extra minute.