Amazon’s Jeff Bezos and SoftBank’s Masayoshi Son have both invested in vertical farming, the burgeoning industry in which crops are grown in stacked layers inside of climate-controlled environments. In the past, the expense of robots, artificial light, and other equipment made vertical farms difficult to scale. But that’s changing as the ecosystem matures and technology improves. Today, thanks to brighter, cheaper LED light bulbs, cloud-based A.I. systems, and more available agricultural sensors, vertical farms can now cultivate lettuce, spinach, basil, garlic, and snow peas. They tend to deliver 10 to 20 times the total yield of conventional farms with far less waste. Vertical farming projects now scatter the globe, settling mostly in urban centers such as Baltimore and Chicago.