"When we use the tree respectfully and economically, we have one of the greatest resources of the Earth," said architect Frank Lloyd Wright. He wasn't kidding. Aside from aesthetic benefits, trees can increase property values by 10 to 20 percent, improve air quality, and, according to Sean Barry of the Arbor Day Foundation, slash air-conditioning bills by as much as 35 percent. Since spring is the perfect time to plant, start now by placing fast-growing deciduous trees, such as red maples or lacebark elms, on the east, west, and northwest sides of your house. They'll block the hot summer sun and, once their leaves fall off, still allow plenty of warming light into your home come winter. While it might take five to 10 years to see substantial benefits, you can start saving energy now by planting a small tree to shade your air conditioner. "Keeping the unit cooler will make it run efficiently," says Barry, "and save you even more money."