For the remodel of his family’s home in San Francisco, designer Peter Liang undertook a two-part landscaping renovation. First, he planted a living roof. Then, with the help of landscape architect Andrea Cochran, he redid the backyard. "I wanted to plant a green roof for its thermal mass, but I wanted it to be as natural as possible," Liang says. The resulting 580-square-foot green roof is like a piece of the hill; its indigenous vegetation—seeded by birds and wind—is irrigated only by seasonal rain and dew. Purple thistles, California poppies, clover, and dandelions have all taken root in the roughly ten-inch-deep, lightweight humus and grape-husk soil.