Valhalla keeps a wall of cut granite at its heart, and the wide green apron below the Kensico Dam sets the standard for what a lawn can look like when somebody loves it. Ace Landscaping carries that standard down the hill into ordinary yards — mowing, edging, trimming and hauling off the leaves that pile against fences and hedges each fall. Winter here is a long rehearsal of thaw and refreeze, so plowing is only half of it; the other half is knowing which north-facing walk turns to glass by evening and salting it first. Most of that happens before the parkway fills and the hamlet is properly awake. Then spring runs up the hillsides early, and the season opens with a first cut that makes a whole street look alive again.