The tallest trees in Thornton are the cottonwoods that came up along the old irrigation ditches, and on a hot Saturday their shade is the most valuable real estate in the neighborhood. Martinez lawn care works the streets under and around them, where the turf is half sun and half dapple and never grows at one speed. Mowing, trimming and edging keep it even; cleanups pull out the cottonwood fluff and fallen twigs that collect against the fences every summer. Kids on bikes, a grill going somewhere, the ditch water moving low and steady — that's the backdrop, and the lawn should look like it belongs in it. Cut clean, trimmed close, swept off, and back to the shade.