In June the old streets of Deering Center go green overhead, and the light that gets through the maples lands in coins on the grass. C.K.C. Landscaping mows, trims and edges through that season, hauls the leaves off in October, and comes back in January with a plow, a shovel and a bag of salt. Portland yards are small and particular — a strip along the walk, a patch behind a triple-decker — so doing them right means hand work as much as machine work. The pleasure is in the finish: a clean line where lawn meets pavement, a walk cleared corner to corner. The crew covers Portland, Westbrook, Falmouth and South Portland.