Rosemary Brook slips along behind the fields at Sprague, and on a July evening the grass there smells exactly like a town in its finest month. NatureWorks Landscape Services, Inc. keeps lawns at that pitch across Wellesley, cutting, trimming, feeding, seeding the thin patches, mulching beds, and hauling leaves away once the color goes. In the cold half the plows and shovels take over, opening driveways and paths and treating the ice that gathers wherever the sun quits early. Working a property in both halves of the year means learning its every soft spot and low corner by heart. That knowledge turns out to be most of the craft.