Indoor-grown produce is available in more than 20 supermarket chains nationwide. But despite massive investment, questions remain about efficiency and costs.

By now, the images of shelves full of perfect greens in hulking warehouses, stacked floor to ceiling in sterile environs and illuminated by high-powered LED lights, have become familiar. Food futurists and industry leaders say these high-tech vertical farming operations are the future of agriculture—able to operate anywhere, virtually invincible against pests, pathogens, and poor weather, and producing local, fresh, high-quality, lower-carbon food year-round.

That future seemed one step closer to reality last year when San Francisco-based indoor farming startup Plenty, which grows a variety of salad and leafy greens hydroponically (without soil) and uses artificial lighting in facilities in three locations, announced that it had raised a whopping $200 million in funding from the SoftBank Vision Fund, whose investors include Amazon founder Jeff Bezos.