Spring is traditionally rhubarb season, and if you’ve ever purchased the vegetable in the winter, you likely noticed a difference in look and taste. That’s because out-of-season rhubarb is grown in complete darkness and harvested by candlelight. So-called “forced” rhubarb is generally the only out-of-season rhubarb available in grocery stores—but it’s also considered a delicacy. 

According to Food52, forced rhubarb is grown in dark hothouses, and uses its own energy stores in the absence of light to grow its stalks. Farmers first grow rhubarb crowns in outdoor fields and then transfer them to a 55ºF hothouse where they are closely monitored. Without light, the leaves turn yellow instead of green, and the stalks are a bright red. They also grow much faster.

“Our stalks are four inches today,” Washington farmer Tim Richter told Food52. “Tomorrow they’ll be eight inches.” The surprising delicacy, which Food52 describes as sweeter and more tender than outdoor rhubarb, grows so quickly you can hear it

Though there are a number of forced rhubarb farmers in the United States, the practice originated in the UK almost two centuries ago. To this day, family businesses in Leeds, Wakefield, and Bradford—an area known as the “Rhubarb Triangle”—are known for their superior forced rhubarb. Check out the video above to watch traditional rhubarb farmers harvest stalks by candlelight, and read the full Food52 profile to learn more about the fascinating practice.

Banner Image Credit: artisanfilm, YouTube