School-grown greens in winter?

Edible gardens at Littlebrook are expanding to the school lobby. As Anne Levin writes in the Town Topics piece: 

In the lobby of Littlebrook Elementary School, two white, vertical fixtures will soon be covered with green. They are part of a recently installed hydroponic garden, designed to allow students who tend the raised bed gardens outside to continue their efforts indoors, during the winter months.The installation is a pilot program of Send Hunger Packing Princeton (SHUPP), which founder Ross Wishnick hopes to expand.