Urban farms are springing up worldwide through any concrete crack foodies can find. As farm-to-table dining trickles down from haute cuisine to fast food, and with increased desire for chef-quality ingredients for home cooking, demand for locally sourced fresh produce is soaring. Concurrently, modern urban sprawl is choking farms around cities, limiting supplies.

With land at a premium, new methods incorporate vertical farming: planting into walls (a larger scale of a home-gardening technique), using three-stories-high A-frame conveyors to rotate plants through water troughs as Sky Greens in Singapore innovated in 2012, and potentially converting high rise buildings into greenhouses. The last suggestion is the vision of ecologist Dickson Despommier, author of The Vertical Farm. Urban gardeners are a resourceful