There is a particular pleasure in a greenhouse in February, when the valley outside is frozen hard and the air under the glass smells like soil and warm water. North River Greenhouse & Landscaping carries that head start out into Alamosa yards once the ground lets go, with mowing, trimming, edging, cleanups and the regular upkeep that keeps turf even from the first cut to the last. Sharp sun and cool nights make grass here grow in bursts, so the schedule follows the weather more than the calendar. A lawn cut in one direction and squared off at the walk holds its shape for a week and looks like somebody meant it. Green is worth something in this country, and it is worth keeping.