At four in the morning in June, the only sound on Sheridan's short blocks is water — heads ticking around, the hiss of a zone finding its pressure. Keeping bluegrass green a mile above sea level, in air this dry, is a matter of timing more than force: the right run time, the right head, nothing thrown at the sidewalk. Bluegrass Lawn and Sprinkler, LLC tunes the irrigation and then mows and edges what it grows. The mower lines come off clean, the edge along the walk is one straight dark seam, and by seven the lawn is cool and holding. Between Hampden and Oxford that is the whole day's work, finished well before the heat arrives.