Swing by Troy Wagner's home in Tacoma, Wash., and you might catch him picking vegetables or watering his pansies. But you won't find him in the yard; he'll be up on his roof, where his garden is. "Parades of people come by to see it," says Wagner, 45, of his suddenly shaggy 110-year-old home. "Everyone says it's pretty."
Wagner is on the neatly trimmed cutting edge of a new fad—green roofs. In recent years more than 500 U.S. homeowners have shucked their shingle, tile or asphalt roofs and replaced them with thriving gardens. Even cities like New York and Chicago—which has some three million square feet of green roofs—are pushing developers to build more of them. The reason? New studies show green roofs help the environment and reduce energy costs. "They make homes cooler in the summer and warmer in the winter," says Ed Snodgrass, who runs a green roof plant supply business in Maryland. By some estimates, energy savings can total 20 percent or more.
But before you start hauling up hydrangea, consider that green roofs cost two or three times as much to install as regular roofing. Yet experts say they should last for several decades with minimal maintenance. "It's like getting a Prius or solar panels," says Snodgrass. "It costs more upfront but there are long-term savings." Besides, say owners, green roofs are just darn neat. "It's weird to want to come home to see how your roof is doing," says Karen Rashcke, 54, who put nearly 11,000 plants on the roof of her Richmond, Va., home. "There's a warm, inviting feeling we get when we come home and see all these flowers dancing in the air."