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At a local FairPrice Supermarket in central Singapore, you'll find baby carrots grown in Bakersfield, Calif. — the same ones for sale at my local grocery store in Washington, D.C.

Such well-traveled vegetables aren't unusual in the tiny island state, which imports more than 90 percent of its food from some 35 countries. Singapore may be one of the most affluent countries in the world, but it depends heavily on others for basic foodstuffs.

A new crop of farmers is trying to change that. Just as property developers build up when they can't build out, so, too, are these agricultural pioneers. Vertical farming is taking hold across Singapore — not only in greenhouses in the vanishing countryside but also on rooftops in the heart of the city, amid soaring skyscrapers and housing blocks. The goal is to farm as efficiently as possible and maximize the remaining land — as well as abandoned and under-utilized spaces — and improve Singapore's ability to provide more of its own food.

In the 1960s, farms occupied about 10 percent of Singapore's 280 square miles, says Ngiam Tong Tau, a former government official who now is chairman of Sky Greens, one of Singapore's vertical farms.

Today, it has shrunk to less than 1 percent to make way for housing and industry.

Not only is land in short supply, but water is, too. Singapore importsan estimated 30 to 40 percent of its water from neighbor Malaysia.

All this means that these new rooftop and vertical farms could make a big difference for Singapore, helping to insulate it from both natural and man-made threats to its food supply that result in periodic food shortages and price spikes.

"In times of emergencies or food shortages around the world, [if] our neighbors ... don't want to export to us, we still have some food left for certain short periods of time until the food emergencies subside," Ngiam says.

Farming High In The Heart Of The City

Once lined with plantations, Singapore's Orchard Road is now a sort of Asian Rodeo Drive. But overlooking the commercial mecca is a different kind of oasis: 6,000 square feet of vegetable and fish gardens.

The aquaponic garden features mint, basil and leafy greens growing in clay pellets in rows on vertical A-frames that draw water from tanks filled with fish. The waste from the fish fertilizes the plants; eventually, the tilapia will become another crop — to be sold or donated to charity.

It's an economical system, says Allan Lim, one of the founders of ComCrop, the startup that built this garden. It costs about $1.60 a day to pump the water through the 10-foot-tall frames, which go for about $1,000 each.

This closed-loop irrigation system makes sense in tropical Singapore since it uses less water and loses less of it to evaporation and runoff than traditional soil farming. Still, for now, ComCrop relies on roughly two-thirds tap water — versus harvested rainwater — to replenish what's lost to evaporation.

Electricity costs are fairly low, too, and ComCrop's central location means it doesn't have to spend much to distribute its food to clients. Its vertical system yields eight to 10 times more crops than conventional, soil-based farming, according to Keith Loh, another one of the company's founders.

ComCrop sells its herbs wholesale to a local distributor that supplies high-end bars and restaurants. But one of the macro problems that these entrepreneurs are addressing is how to help Singapore's food supply withstand external disruptions like drought, flooding or trade restrictions due to regional public health issues — for example, when Malaysia halted poultry exports during the country's 2004 outbreak of avian flu.

Next year, they hope to scale up the farm by 10 times at another building that houses 80 food-processing companies, with a goal of producing 23 tons of food per month.

"Our goal is that when a time of need comes, the rooftop farm can convert into something important," Lim says.

From Ghost Town Garage To Showcase Garden

Atop the mostly empty garage of the People's Park Complex, a massive housing and commercial development in Chinatown, is a pop-up boutique, spare with a minimalist color palette and lots of reclaimed wood. It wouldn't look out of place in Brooklyn.

It's an outpost of Edible Gardens, a design firm founded two years ago by Briton Rob Pearce and Singaporean Bjorn Low that does foodscaping and landscaping for hotels and restaurants.

"Space in Singapore has to work really hard," says Pearce, who comes from a family of farmers in Somerset, England. "People see what we're doing, so it has to be beautiful."

The next beautification project is turning half of the garage's 60,000-square-foot roof into a farm. Pearce sees rooftop gardens that use otherwise abandoned or underutilized spaces as a win-win solution for developers and urban farmers.

Reaching Higher In The Countryside

Singapore's vanishing countryside — accessible via a 40-minute ride on the immaculate and ultra-punctual MRT train — is home to Sky Greens, one of the world's first commercial vertical farms.

Though Sky Greens has put down roots on 8.6 acres, its crops grow in greenhouses on 30-foot-high vertical frames with hydraulic rotating troughs that bring the plants down to water and then up to the sun.

This kind of farming, says Ngiam, Sky Greens' chairman, yields five times more food than conventional farming.

"For every [2.5 acres], we should be able to produce 1,000 tons of vegetables per year — or about 1 percent of Singapore's needs for leafy green vegetables," Ngiam says.

With about half of the farm developed, Sky Greens is already producing 1.5 to 2 percent of Singapore's demand for leafy green vegetables such as baby bok choy, Chinese water spinach and Chinese broccoli, he says. Eventually, the farm will have 2,000 A-frames, which cost about $12,000 each.

Like other urban farms in Singapore, one of Sky Greens' advantages is how little water it uses, relying primarily on collected and recycled rainwater. And its system of hydraulic-powered rotating troughs means less spent on electricity, and even less water is wasted.

"The troughs come down and go into the water and go up. So there's no leaching of the water," Ngiam explains. "If you are planting on the soil, what the farmer does is pour a lot of water, and then it just leaches out. For us, every drop is used by the plant."

Another advantage is that Sky Greens products can go from harvest to market within the same day. By comparison, vegetables from Malaysia travel one to two days to market.

Sky Greens vegetables do cost more: up to $2 per 3.5-ounce package, or about 10 percent more than vegetables from Malaysia. But Ngiam thinks some middle- and upper-income Singaporeans are willing to pay that premium.

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