Patrons at a few Tel Aviv restaurants may have noticed their lettuce has a strange new taste recently: the taste of freshness. Two Tel Aviv restaurants are serving up lettuce that was grown in floating beds of water on the rooftop of Dizengoff Center, in an innovative new urban gardening system that aims to provide city dwellers with straight-from-the-farm veggies.

“People are used to lettuce tasting a certain way, after it’s been sitting in a bag in the refrigerator for a week,” said Mendi Falk, the 42-year-old director of Green in the City, a hydroponics project in the center of downtown Tel Aviv. “With hydroponics, the lettuce is harvested just 15 minutes earlier. It has a different taste.”

Falk runs his 100 square meter farm, which supplies leafy vegetables for two restaurants and a farmer’s market in Dizengoff Center, on the roof of Tel Aviv’s central mall with just three hours of labor per week and 120 watts of power (the average household light bulb is 60 watts). He utilizes a number of different hydroponics systems, which means that his vegetables grow while floating in a special blend of water and fertilizer.

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There is no dirt whatsoever. There’s also no weeding, no extra watering or fertilizing processes, and no pesticide spraying.

“I went to the Technion for computer engineering and was in high-tech for ten years until I got burned out,” said Falk, as he tended to a raised garden bed of lettuce heads poking out of holes in a Styrofoam sheet. “I wanted to be a farmer, and I had a dream of driving a tractor. But now, I’m in the high-tech of gardening.”

Israel has a long history of hydroponics, especially for leafy vegetables, because it helps avoid the presence of pests that make the produce nonkosher; usually, supervised bug-free leafy vegetables are expensive and laden with pesticides. Gush Katif, a Jewish area in the Gaza Strip that Israel withdrew from in 2005 was especially known for its hydroponics greenhouses because the Gaza soil was too sandy for most agriculture.

The Green in the City project wants to utilize hydroponics as a way to incorporate agriculture into dense urban environments.

According to the UN, 54% of the world’s population currently lives in cities, and this is expected to increase to 66% by 2050, when more than six billion people will live in urban environments. As city living becomes more and more widespread, the world needs to figure out how to grow enough food to feed those people who do not have their own land and do not grow their own food.

Hydroponics has a number of advantages over traditional agriculture in urban environments. The most prevalent, of course, is the small space requirement. With the floating rafts, Falk can grow four times the vegetables that would be possible in the same amount of space in the ground. For the vertical pipes pictured above, he can grow eight times the amount of vegetables in a traditional garden. This is because the special blend of nutrients and fertilizer added to the water goes straight to the roots of the plants, so the plants can grow closer together. The systems also use significantly less water – about 20% of the amount plants in the ground would require.

Falk says he doesn’t miss the visceral feeling of immersing his hands in the soil while planting rows of vegetables. “There’s an energy in the earth, but there’s also an energy in the water,” he said. Many people start home gardens with good intentions, but get frustrated as the soil gets depleted of nutrients and becomes less productive. “Here, you control everything exactly, so it’s a way for people to get green into their lives.”

Green in the City will host hundreds of people at educational seminars this summer. It will run special workshops aimed at children as young as 4 years old, as well as retirees from across the country. But the garden isn’t just for show and tell.

Falk also wants the garden to be self-sustainable financially by selling the produce to local restaurants. The current project is too small to be commercially viable. Falk estimates he would need about 500 square meters to harvest 1,500 plants per month to have a financially stable urban farm.

The current project grows leafy vegetables for two restaurants in Dizengoff Center, Café Greg and chef Nir Zook’s Garden Restaurant, as well as the Dizengoff Center Farmer’s Market. There is also a waiting list of restaurants that want to purchase the hydroponic vegetables. Falk plans to expand the project to other parts of the Dizengoff Center Roof, as well as other buildings around the city.

He also wants to start satellite hydroponics projects for local restaurants in Netanya, Haifa, and Holon, where restaurants have expressed interest in purchasing his vegetables. Eventually, Falk envisions a business where a network hydroponic roof system will supply vegetables for each square kilometer of the city. And every restaurant will have its own section of a rooftop garden, growing rare vegetables at their chefs’ requests.

One interesting aspect of using hydroponic vegetables means that restaurants can store their produce in water and use just what they need for the day, reducing waste from unused vegetables. This also means that salads will have components harvested literally moments before they arrive on customers’ plates.

Growing hydroponics on the roof of a building does have limitations. Falk concentrates on leafy vegetables because they have the shortest life cycle. Falk also grows strawberries, tomatoes, onions, herbs, cucumbers, kale, and even papaya in the hydroponic systems. Fruit trees can grow well in hydroponics, but it takes so long for them to reach the harvest stage that it is not feasible, because space is limited on rooftops.

Green in the City also has aquaponics systems on the rooftop, which feature a closed system of vegetables connected to a small fishpond. The fish’s waste is the fertilizer for the plants.

Falk’s other company, LivingGreen, also offers individual hydroponics systems for sale for family use. Customers can design their own system to fit on a balcony, which includes a pump to ensure regular circulation of water.

Last year, LivingGreen won $20,000 from the Pears Challenge for its “LivingBox” mini-farm design, which does not require land, running water, or electricity. The aim is to help people in third-world countries grow their own food, though urban denizens in Israel can also purchase their own for NIS 150.

Growing on rooftops in Tel Aviv also requires some creativity. “We had a hard winter, mainly because of the wind,” said Falk. “The tall vegetables were just destroyed in the wind. Before a big rain comes, we put nylon over [the beds] to protect the plants.”

There’s also an issue of air pollution in cities, which Falk said is still being studied to understand how it affects the plants. However, he pointed out that vegetables, and especially leafy vegetables, are sprayed with massive amounts of pesticide in the fields, while in the hydroponics system they do not use any pesticides. The fertilizers added to the water contain things like garlic and nicotine to ward against pests, and are certified organic.

Green in the City found their home on top of the mall because Dizengoff Center has a number of environmental initiatives. Also on the rooftop are ten working beehives and a tree nursery with more than 1,400 trees, which are destined for planting around the city in community gardens. The projects are part of the mall’s effort to reduce its carbon footprint by 15%.

On June 23, Dizengoff Center won the Green Globes, the environmental equivalent of an Oscar, as the greenest business for the 12th year in a row. An umbrella group of more than 130 environmental organizations called Life and Environment – The Israeli Union of Environmental NGOs awards prizes in a number of categories each year to businesses and organizations that are committed to improving the environment.

The Center offers roof space to new urban sustainability organizations, like Green in the City, to help them get started so they can hopefully spread throughout the city. The 40,000 square meter (435,000 square feet) mall has more than 400 stores. Over the past years, it has also reduced its electricity consumption by 13% through a variety of conservation initiatives.

As the sun set across a bed of spices, Falk made a few more checks to measure the pH of the water with a device that looks like a thermometer. With a panoramic view of tall buildings glowing orange in the setting sun, the rooftop project doesn’t bear much resemblance to the traditional concept of a farm. But this pocket of green, surrounded by skyscrapers, may be the future for vegetables for city-dwellers.