Hydroponics — growing plants in nutrient-rich water rather than soil — might seem like a fairly modern idea, but people in China have used the technique to grow rice since at least the 13th century.

WYKOFF — In his high-tech cargo container behind Wykoff's Minnwest Bank branch, Tony Rahe takes a tray of greens off a nursery shelf and places it on a counter. The tray and its clear lid, used to ...