Behind the bay windows and painted facades of Noe Valley, San Francisco keeps its hidden gardens: narrow rectangles of green running back from the row houses, walled by fences and neighbors' rooflines. Katharine Webster Landscape Design brings a designer's eye and steady lawn care to these small city spaces, where every square foot of grass can be seen from three stories up. In spring, when the fog thins by midday and sun drops straight down between the houses, a lawn of the right shape becomes the room the house was missing. Margins drawn true, turf cut to an even nap: in a yard this size the details carry, because there is nowhere to hide them. It is a backyard you glimpse from the stairs and want to step into.