The Best Rhubarb Grows in the Dark

A technique known as forcing produces this springtime delicacy.

Published Mar. 30, 2021.

Around 1817, a team of workers digging a ditch in London inadvertently sparked a horticultural revolution. The ditch was in the Chelsea Physic Garden, on the bank of the River Thames. The spark was the accidental burial of some dormant crowns of rhubarb, that celery-like vegetable that was, at the time, primarily used as medicine. While field rhubarb is a warm‑weather crop, fresh, salmon‑colored stalks started poking out of the dirt mounds in the Physic Garden that winter—the first of many surprises in the unlikely life of cultivated rhubarb.

After that, accident became technique: The cultivation method is known today as rhubarb forcing. The practice has been perfected in northern England’s “Rhubarb Triangle,” the area between Leeds, Bradford, and Wakefield, where the cold, wet climate mimics that of rhubarb’s native Siberia. Produce from the Rhubarb Triangle is of such quality that Yorkshire forced rhubarb was awarded Protected Designation of Origin status in 2010. “Outdoor rhubarb is a bit stringy and wooden and sour,” Robert Tomlinson, a fourth-generation grower in Pudsey, West Yorkshire, told me. “Forced rhubarb is a lot more tender.”

Tomlinson’s farm has been in his family for more than 140 years, passed down from his great-grandfather, Robert; to his grandfather, Bernard; to his father, David; to him. (“I remember going into the sheds when I was 6 or 7 years old,” Tomlinson said, “probably getting in the way, really.”) Tomlinson largely adheres to the same growing methods that decades of Yorkshire farmers have passed down.

Forced rhubarb begins with rhubarb roots grown outdoors for two years. In their second autumn, the plants go dormant, and they reawaken in early December. That’s when it’s time to transport the roots, some of which can weigh more than 100 pounds, indoors. The magic unfolds in “forcing sheds,” warm, cave-like spaces where rows of plants use their stored-up energy to grow in total darkness. The only light forced rhubarb sees is the soft glow of candles, lit to help growers see at harvest time.

In the sheds, the darkness and warmth “trick” the rhubarb, simulating springtime. “It grows because it’s looking for the light,” Tomlinson explained. The darkness restricts photosynthesis, yielding sweeter, more tender, and brilliantly hued plants. And forced rhubarb can grow at a fairy-tale-like rate—the plants typically grow from the ground to 2 feet tall after just four weeks in the shed. Some even say the rhubarb grows so fast that you can hear the plants “sing,” creaking and popping in the darkened sheds.

But Tomlinson is more than a little dubious about the sounds. “Well, people say that just because it grows really quickly,” he said. However, his answer to my next question—about the best way to consume forced rhubarb—was much more decisive.

“I like it in gin, myself,” he said with a laugh.

Rhubarb Upside-Down Cake

For a springtime dessert with a twist, we layer a cardamom-and-lemon-scented batter with jammy rhubarb and a crunchy almond streusel.
Get the Recipe


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