Dumont sits in the Northern Valley with the ridge on one side and the river country on the other, a mile and a half of borough that greens up all at once in May. Tri-Valley Landscape Contractors takes care of the lawns inside it — cutting, trimming, edging, spring and fall cleanups, beds and borders kept tidy. Mid-morning is a good hour for the work, the dew burned off, the mower leaving clean stripes across a front yard. Grass here answers quickly to attention, and a lawn left to itself can be turned around in a few visits. That change is the whole point of the trade.