April climbs the hillside from the river in stages, and the terraced yards of Dobbs Ferry green from the bottom step to the top. Beautiful garden landscaping starts its year there: cutting back what winter flattened, raking the beds open, mulching, and taking the first cut off a lawn that has been waiting since November. This part of Greenburgh is all slope and stone, which makes a level, evenly mown lawn a small act of persuasion. Through summer the visits stay steady — mow, trim, edge, tidy the borders — and by October the leaves are gathered and the beds put down for the cold. A yard kept this way looks cared for from the sidewalk, which is the entire idea.