A garden in Santa Monica, Calif. Courtesy of Cultivate LA hide caption

itoggle caption Courtesy of Cultivate LA

Stacey Kimmons and Audra Lewicki harvest lettuce at the Chicago Botanic Garden's 20,000-square-foot vegetable garden atop McCormick Place West in Chicago. Courtesy of the Chicago Botanic Garden hide caption

itoggle caption Courtesy of the Chicago Botanic Garden

Sheep graze in the street last year in Cairo. Gianluigi Guercia/AFP/Getty Images hide caption

itoggle caption Gianluigi Guercia/AFP/Getty Images

This "pinkhouse" at Caliber Biotherapeutics in Bryan, Texas, grows 2.2 million plants under the glow of blue and red LEDs. Courtesy of Caliber Therapeutics hide caption

itoggle caption Courtesy of Caliber Therapeutics

Uncommon Ground, a certified green restaurant in Chicago, hosts an organic farm on its rooftop. Zoran Orlic of Zero Studio Photography/Uncommon Ground hide caption

itoggle caption Zoran Orlic of Zero Studio Photography/Uncommon Ground

Mah Bow Tan, a member of Singapore's Parliament, inspects Chinese cabbage growing at the commercial vertical farm. Troughs of the veggies stack up to 30 feet in the greenhouse. Courtesy of MNDsingapore. hide caption

itoggle caption Courtesy of MNDsingapore.

Guerrilla grafter Tara Hui grafts a fruiting pear branch onto an ornamental fruit tree in the San Francisco Bay Area. She doesn't want the location known because the grafting is illegal. Lonny Shavelson for NPR hide caption

itoggle caption Lonny Shavelson for NPR