To harness the effect, they started projecting light through an old 35mm Kodak projector onto a swath of grass on the wall. In the years since they have perfected the process. The area where they grow their installations needs to be totally dark except for the light coming from the 2,500-watt projector that serves at their light source. They use large, specially made 7x7-inch negatives to project on vertical walls. It's quite literally like a biological dark room.