By Rob Pittam
Rhubarb stalks are developed in the dark
Step into the secret sheds of the Rhubarb Triangle and you enter a quieter, more relaxing world.
Hushed workers gather armfuls of rhubarb by candlelight.
The only noise, a gentle hum of the heater keeping the plants warm in the darkness.
In the nursery sheds the silence is so complete you can actually hear the rhubarb growing.
The air is filled with the ripping sounds of buds opening up and developing into stalks.
The Rhubarb Triangle is an area of West Yorkshire farms bordered by Leeds, Wakefield and Bradford.
The plant is a native of Siberia and enjoys the wet cold winters here.
But it was the forcing sheds that gave the Rhubarb Triangle its edge.
West Yorkshire once produced 90% of the world's winter rhubarb
The plants spend two years out in the open, absorbing sunshine and storing energy.
In the sheds they are placed in darkness and warmed by heat that was once supplied by abundant cheap coal from the Yorkshire coalfield.
It means they concentrate on growing longer, sweeter stalks, rather than producing leaves to absorb sunlight.
The technique was developed in the 1870s and over the years it has been honed to perfection.
But the Yorkshire growers jealously guarded their secret - strangers weren't welcome in the shed.
In its heyday there were two hundred growers in the Rhubarb Triangle and it produced 90% of the world's winter rhubarb.
Janet Oldroyd is the fourth generation of a family of rhubarb growers and an expert on its history.
Janet Oldroyd's is one of only 12 remaining growers in the area
"The first written record of rhubarb being used is from four thousand years ago," she said.
"Then it was used for medicine, as some strains of rhubarb still are. It came to Britain in the 13th century and at the time it was four times more expensive than opium!"
Gradually it became used as a food and the rhubarb sheds meant it was the only fresh product available in the winter.
But after World War II it went into decline as other, more exotic fruit appeared.
"It was an overexposed star," said Janet.
"There was a whole generation which was basically force fed rhubarb.
"After the war we started to get all kinds of fruit coming into the country and people just stopped eating it."
But now rhubarb is enjoying a resurgence.
"There are two things going for it.
"For one thing people are rediscovering the health benefits of eating rhubarb and it fits into modern tastes," said Janet.
Rhubarb leafs contain the poison oxalic acid
"People used to have a really sweet tooth but now we like a bit of sharpness - that's why cranberries are so popular now.
"To be honest, it's come just in time because if things had carried on as they were, there wouldn't have been any rhubarb growers left."
As a sign of the changing times, the Oldroyd farm will produce 150 tons of rhubarb in the next few months.
A few years ago they would have struggled to sell it, with wholesalers taking almost all of the plants.
Now though, 90% is going straight to supermarkets as the public rediscovers its appetite for rhubarb.