possible is called hydroponics and it not only keeps this restaurant supplied with food he grows himself here above the city, but in the bigger picture he thinks it could become a model for all of us to grow what we need very close to home. >> i can produce right here for myself in abundance. and all i have to do is go on the roof. >> reporter: the key is water, or more specifically, water without soil. seven weeks ago these were all seeds? >> yes. >> wow. >> one of the benefits of hydroponics is rapid growth. >> reporter: mooney's using a system where water filled with nutrients circulates through these towers, each which of can sustain dozens of separate plants. the absence of real soil keeps the system lightweight enough and upright enough to fit into small spaces like a rooftop. it also eliminates plant diseases and pests that can live in the soil. >> this is our bibb. >> bibb lettuce? >> yes. you see the beautiful head of lettuce, totally beautiful roots attac