For over 200 years, rhubarb farmers in Yorkshire’s nine-mile-square “Rhubarb Triangle” have been using an ingenious method—or trick, some might say—to coax their rhubarb plants to grow faster and taste sweeter. Yorkshire Forced Rhubarb is so prized that it has earned a “protected designation of origin” from the European Union.
Plant lovers may cringe at the techniques used to compel the rhubarb to grow in this way. During the winter, usually after the first long frost in November, the plants are dug up from the fields and placed in dark, windowless, heated sheds. A few days later, they begin to grow at an incredible rate—sometimes an inch per day or even more. The specific combination of environmental cues (frost followed by warmth and darkness) puts the rhubarb under a great deal of stress. The confused plants “think” that spring has come when they reach the warmth of the sheds, yet their photoreceptors detect that it is dark and that something is wrong. The plant then begins to grow rapidly, straight upwards, in an attempt to reach the light.
Photosynthesis isn’t possible without light, so the plant uses carbohydrates stored in the underground roots to provide the energy for the stalks to grow. This process makes the new growth much sweeter, and the stalks become weaker as the cell walls stretch and elongate. This may not be good for the plant’s survival, but it makes the rhubarb much more tender. The plant also takes on a shocking pink hue without the green photosynthesizing pigment chlorophyll.
So where does the candlelight come in? This method may seem quaint, but it’s also essential. If exposed to enough light, the process will be disrupted, so rhubarb growers use candles to check whether their plants are ready to harvest.
The resurgence of the Rhubarb Triangle:
- *For a time, 90% of the world’s “forced rhubarb” was grown in the “Rhubarb Triangle.” There were around 200 forced-rhubarb growers in the region in the 1930s. It became a hugely popular commodity during World War II, thanks to government price controls (one shilling per pound). But during the 1950s and 1960s, rhubarb lost its appeal. It had been overused during the war, was too tart to enjoy when sugar was rationed, and couldn’t compare to the exotic new tropical fruits arriving thanks to refrigerated transport.
- *Rhubarb can be used in a wide variety of ways. Though technically a vegetable, it often functions as a fruit for culinary purposes. It can be used for either sweet or savory dishes and is a popular choice for jams, crumbles, and other desserts. It also pairs well with other vegetables when roasted.
- *Only around nine families currently grow rhubarb in the Rhubarb Triangle, but the crop appears to be making a resurgence. The annual Rhubarb Festival, held every February, has become a major tourist attraction, with farm tours, demonstrations, talks, and music, plus numerous food and drink items incorporating the highly versatile plant. Rhubarb's returning popularity is also due in part to the boom in home baking, especially when it incorporates local produce. And as a perennial, rhubarb is a hardy, reliable option in the face of climate change.
- *The health benefits of rhubarb are widely touted. Recent studies suggest that it may be helpful in stopping the growth of cancer cells thanks to its high concentrations of polyphenols. Some people seek it out due to its high fiber content and low caloric density.