ON A BRISK WINTER morning, Kimbal Musk is an incongruous sight in his signature cowboy hat and monogrammed silver K belt buckle—his folksy uniform of the past few years—as he addresses a crowd outside a cluster of shipping containers in a Brooklyn parking lot. Inside each container, pink grow lights and fire hydrant irrigation feed vertical stacks of edible crops—arugula, shiso, basil and chard, among others—the equivalent of two acres of cultivated land inside a climate-controlled 320-square-foot shell. “This is basically a business in a box,” Kimbal says, presenting his latest venture to its investors, friends and curious...