A west-side backyard in late May, bikes on their sides, a sprinkler ticking somewhere down the block — that is the Watertown that Happy Grass keeps. Mowing on a steady week, trimming around swing sets and garden beds, edging so the driveway holds its shape all summer. Grass cut at the right height stays greener through the dry stretch in July and takes the first cool nights better. Beds get cleared out in spring; leaves get gathered in fall so the lawn can breathe under whatever the winter brings. It is uncomplicated, cheerful work, and the yard shows it every time somebody steps outside.