If you want to know what spring means in Novato, look up at Mount Burdell in March, when the rains have turned its shoulders an almost impossible green and the oaks stand dark against the slope. Andrew McAghon Landscaping works the lawns below that hillside, where the same wet months that color the mountain send grass in town racing ahead of the mower. North of town the meadows of Olompali run down toward the Petaluma River marshes, and the morning air smells of bay laurel and damp earth. This is the season for mowing that keeps up with the rush, tight trimming along walks and beds, and clearing out the leaf litter the winter storms left behind. By May the hills begin turning gold, and a lawn looked after through the spring flush holds its shape well into the dry months.