Meet the Farmers Growing Crops in a World War II Shelter

LONDON— -- Deep down below the busy streets of London, two British entrepreneurs are growing crops in a former World War II air-raid shelter.

Richard Ballard and Steven Dring started Growing Underground in 2015 and claim it's “the world’s first subterranean, urban farm.” Their crops include pea shoots, garlic, chives, red basil, mustard leaf, radish, coriander and a dozen more, sold to online distributors, at farmers markets and mostly to a wholesale market that distributes to thousands of restaurants around London.

The location, a tunnel 110 feet below ground, was designed to accommodate up to 8,000 people in case of bombings during World War II. But it’s not the only unique aspect of this venture.

“We are dedicated to minimizing our carbon footprint,” the founders said. While their use LED lights to grow crops means they have a low carbon emission, some experts say their carbon footprint is not zero.

"The electricity they use comes from an electrical power plant," Professor of Horticulture Cary Mitchell of Purdue University told ABC News, adding: "LEDs are not yet more energy efficient, but they have special properties. The lights are much closer to the crops, which means that less power, and less energy, is required."

Growing crops with LED lights saves up to 60 percent in energy, Matt Davey, a plant physiologist and chemical ecologist at Cambridge University, told ABC News.

The most important thing for their crops, horticultural director Chris Nelson told ABC News, is the quality of their LED lights: “We had to find the right type, with a range of spectrum. We found this one at a Finnish company, and it’s perfect, because for growing you need red and blue LEDs.”

Hydroponic growing is a farming method that does not require soil. In this case, the material is made of recycled carpet. The farm's unique environment and technology also means they use 70 percent less water than traditional farming methods, according to the founders.

“This is perfectly healthy. I can control the amount and quality of light they receive; the atmosphere, the water; and give them the perfect conditions for growing," Nelson added. Having control over the environment means Nelson and his team can predict harvesting times -- which goes from four to 15 days depending on the crops -- and increasing productivity.

Davey believes this project provides a model for future farming, and could be used for growing on Mars, for example. The technology works especially well with high-quality plants like Growing Underground's micro-greens, according to Davey. "With LED lights you can change the wavelength emitted, which means you can change the chemical composition of the plant," he said.

But Growing Underground is first and foremost a business venture, who have chosen to grow micro-greens because they are "quick turning," and thus the most profitable.

"LEDs are three to five time more expensive then traditional lighting, but you save energy," Mitchell said, adding "this industry needs a lot of more research to be profitable."

Dring said one of the major challenges is "working in an underground location." "But we have a lot less issues like pesticides, fungicides. We don’t face those challenges here," he said.

Being underground means they can leverage the natural coolness of the location, but they have to deal with potential humidity problems, Mitchell said.

The next step, Dring said, will be expanding the farm to the 2.5 acres available in the tunnel over the next few years.