After Riley moved to Brooklyn, New York, in 2003, she grew potted vegetables in her dimly lit apartment. The results were far from successful. Her plants strained for light on a confined windowsill, and they poured their energy into growing expansive root systems instead of lush, edible greens. A rooftop garden, meanwhile, exposed her crops to the Northeast's finicky weather. Riley thought using the entire vertical, sun-soaked space of a window -- not just the sill -- could grow more and healthier vegetables. Stringing planters together seemed like the answer.