New York is a city notoriously short on space, but also one whose residents are big on innovation. In the Big Apple, the latest trend is rooftop farming. Individuals and restaurants are beginning to grow some of their own food in the only space available to them - their roofs. While the practice is currently an environmental rather than a financial trend, some companies hope it can become a money-making business model, providing a cheaper alternative to store-bought produce, especially in low-income neighborhoods where fresh vegetables are expensive and scarce. Paige Kollock reports.