Amber Kusmenko and her boyfriend Louis Kofsky love New York, but they also love farming. Thanks to the new trend called "rooftop farming," they can experience both. What started as an interest in sustainability has become a rooftop oasis, complete with tomatoes, cucumbers, carrots and herbs.

After reading books and talking to other growers, the couple learned how to make soil, grow plants, capture rainwater, and trap urban heat.

"Instead of saying, 'oh one day saying we're gonna buy a farm', we said, 'let's start now', and lets start growing and let's start learning, so that we have these skills, and that we've made mistakes up here when we still have the supermarket down the street."

"Also, with so many people on the planet, people have to live in cities. We can't all go out and have 100 acres. I think there are ways that cities can be green and sustainable and grow a lot of their own food."

Roberta's Pizzeria is a thriving example. In an effort to beautify their unattractive parking lot, the restaurant bought two old railway cars and planted a variety of vegetables on top of them, turning the lot into a garden and seating area.

Gwen Schantz is the garden manager. "We supplement the menu in there with some food from our garden, and people love it when we say 'this salad came from out back and this basil was grown outside."

While Schantz's operation does not provide enough food for the restaurant, she says they plan to purchase a bigger rooftop space that will.

A company called BriteFarm Systems is banking on that. It provides rooftop farms to schools, non-profits, and corporations.

Director Benjamin Lindley says, once they are built, rooftop farms can provide cheaper produce. Currently, many fruits and vegetables come from thousands of kilometers away.

"That transportation distance is a problem. It's a problem for the environment, it's a problem for the farmer, and it's a problem for the consumer because your vegetable is still perishable, and often, by the time the vegetable reaches us here in New York, it's heading towards the end of its shelf life."

The company is working on at least four rooftop farms throughout the city, which it says will be up and running early next year.