The ground under Thornton is high-plains clay, and by midsummer a well-loved lawn has been walked, watered and mowed until that soil packs down as tight as a driveway. Dawn to Dusk Lawn Aeration works the long side of a Colorado day for exactly that reason — first light through the blue hour after the sun drops behind the Divide. Cores come out in neat rows and dry on the surface like a little topography, and the turf breathes for the first time in months. Along with aeration, the route carries mowing, trimming and edging so a lawn gets both the deep work and the weekly upkeep. Grass here has to earn its green against thin air and fourteen inches of rain a year; loosening the ground is how you help it.