In ancient times, rhubarb was revered for its mysterious cathartic powers. Today, a small community of farms in Yorkshire’s "Rhubarb Triangle" keeps some of this strange plant’s secrets alive.

Each winter, acres of rhubarb plants are transferred by hand into long, dark nursery sheds to be "forced". They grow at an accelerated rate in the light-free hothouses, which are so completely silent you can hear the "pop" as the buds of new stalks burst open. Workers harvest armfuls of stalks by candlelight to preserve the younger stems that are still growing.

“Any light on it would spoil the crop,” said Janet Oldroyd Hulme, “it’s as pitch black as a coal mine in there.” Her family has been growing rhubarb on their West Yorkshire farm in the Leeds, Wakefield and Bradford "triangle" for five generations.

Heat tricks the plants’ hormones into triggering growth. Without light they feed on energy from their roots. After only a few weeks the delicate stalks are ready to be hand-harvested by candle-light in much the same way as in Victorian times when the method was invented. “We go in with candles because it’s a dim light and doesn’t spoil the conditions,” says Oldroyd Hulme.

The harvested stalks are tender, sweet, and a distinctive bright pink in colour with tiny curled yellow leaves that makes forced rhubarb instantly recognisable. Known as champagne rhubarb it is considered a delicacy and can fetch prices three times higher than its more fibrous and bitter outdoor equivalent.

Originally a native of Siberia, rhubarb flourishes in Yorkshire’s cold, damp soils. In the 1800s when the cultivation method was invented coal for the sheds was provided by nearby coal mines and fertiliser from the by-products of the wool industry. New plants grow for two years without harvest, storing energy from the sun in their roots as carbohydrate, like the human body stores fat. Frost causes plants to hibernate and transform the stored carbohydrate into glucose, crucial for forced rhubarb’s bittersweet flavour.

Chefs have championed rhubarb as a savoury ingredient and shown it can be much more than just a homely ingredient for crumble. Its sharpness makes it an ideal companion for high-fat meats such as duck and oily fish.

“It is a taste of today. People have learned they must cut down on sugar and developed a taste for sharper flavoured fruits like blueberries and cranberries,” said Oldroyd Hulme.

Rhubarb is now classified as a superfood for its ratio of health benefits to calories – only 7 calories per 100 grams. Savvy slimmers have also realised it actually speeds up the metabolism. High levels of calcium mean it is a fat-free alternative to dairy products which lowers cholesterol.

In the 16th century rhubarb’s healing properties were so sought after that it sold for more than opium. It went out of fashion after the Second World War when exotic fruits flooded the marketplace.

Contemporary food lovers are reacquainting themselves with the accepted wisdom of old and it is firmly back on the menu. Supermarkets reported a 100 per cent increase in sales this January in comparison to 12 months ago, a bigger rise than in any other vegetable.

Graham Oldroyd, 57, president of the Leeds and District Market Gardeners Association, part of the National Farmers Union, says: “Rhubarb is becoming a niche product. We aren’t organic but we use very few chemicals – people like that."

Wakefield Festival of Food Drink and Rhubarb takes place on 7-8 March 2008.

Janet Oldroyd Hulme hosts candle-lit tours of her rhubarb forcing sheds throughout the Festival. For more details go to: www.yorkshirerhubarb.co.uk

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