In Mohave Valley the day belongs to the sun and the evening belongs to the river. When the heat finally leans off the Colorado and the cottonwoods down toward Topock Marsh go gray-green in the last light, that is the hour for mowing, trimming and putting a yard back in order. A Toe Truck handles lawn care on the valley floor, where grass grows only for the people who tend it and every cut border is a small argument with the desert. Winter is the gift here — mild mornings, shirtsleeves instead of ice water — and the lawns show it. The result is worth the early start and the late finish: a trimmed yard holding its shape in the bend of the river.