The dark art of forcing vegetables


Rhubarb produces pink sticks like Blackpool rock when forced
Rhubarb produces pink sticks like Blackpool rock when forced

I learn more about how to force winter vegetables with expert help from Britain’s foremost growers

Something magical happens at this time of year behind the closed doors of garden sheds, under terracotta pots and inside dustbins.

Under the cover of darkness, gardeners and growers are nurturing some of the most sought-after gems of the vegetable world, transforming the acidic and thick-stems of rhubarb into pink sticks like seaside rock, the fronds of sea kale into a fluorescent frizz and the leaves of chicory into pale and sweet newborns.

“I remember creeping into the forcing shed when I was four and it was as if I’d opened the doors to Narnia,” says third generation Yorkshire Forced Rhubarb grower Ben Asquith. “It was like a secret kingdom with glowing candles and warm air – it was totally magical.”

Force of habit

It’s said forced rhubarb was discovered by happy accident in the early 19th century when a gardener accidentally buried a rhubarb plant in his compost heap, only to discover the shocking pink stems later on. During the rhubarb-forcing heyday of the 19th and early 20th century, the Rhubarb Triangle covered 30-square-miles between Leeds Bradford and Wakefield with 200 tons sent to London markets by the ‘Rhubarb Express’.

Ben Asquith was just 14 when he started forcing rhubarb at his family’s Brandy Carr Nursery in Yorkshire’s famous ‘Rhubarb Triangle’, with skills passed down from his father and grandfather.

“I was six-years-old when my mum cooked forced rhubarb for me for the first time and I couldn’t believe my eyes when I saw the colour, I thought I was in a sweet shop,” he says. “My granddad ate a dish of rhubarb every day of the year and swore blind it kept him alive – he lived well into his 90s.”

Despite this rhubarb-growing lineage, which dates back some 100 years, the fundamentals of forcing have changed little in that time.

The ruby red of the rhubarb crown is forced into action
The ruby red of the rhubarb crown is forced into action

During the summer the rhubarb crowns are ‘fattened up’ in the field, storing energy for the task ahead, and Ben remembers his father using shoddy (wool waste) from the local mill and muck from Leeds to pep up the plants. During the winter, the dormant crowns are left outside so the frosts can spark them into action before being transferred to the forcing sheds where their stored carbohydrate turns to sugar. Delicate handling is key to a good crop, to ensure no damage is done to the developing buds, but this can be hard when they can weigh anything up to four stone.

“When we lifted with horse and cart, it was very hard on the horses and they used to get Saturday afternoon off and all day Sunday,” says Ben. “Now we have a tractor it’s easier, but it remains one of the most back-breaking jobs and it can take two men to lift one. I broke a garden fork in half once. I always say there’s more men with hernias in West Yorkshire than anywhere else!”

Placed on the floor of the cavernous forcing sheds, paths are created between the plants and soil pushed into the crown’s crevices so the fibrous roots get plenty of nutrition, before they’re given a good soaking.

“Everything’s still done by hand,” say Ben. “And we can stand for hours with our thumb over the end of the hose!”

Forcing rhubarb at home involves covering it with a pot, trug or box
Forcing rhubarb at home involves covering it with a pot, trug or box

With no light but plenty of moisture and under floor heating (originally supplied by stoves fuelled by Yorkshire’s prodigious coal fields), shoots begin to develop in four weeks and when harvesting time arrives, Ben continues the practice passed down from his ancestors of picking by candlelight.

“We continue to use the method my granddad devised of putting a candle into a tin fixed to the top of an old broom stick,” says Ben. “We can’t risk bringing too much light in, because it would produce green leaves.”

For a forced rhubarb grower, the measure of success is the colour of the crop: pale fuchsia stems with the bright yellow arrow shaped leaves on top, traditionally sold ‘leaf-on’ to maximize this dazzling contrast.

All at sea

While celebrity chefs might wax lyrical about the pink pins of rhubarb, you’ll be harder pressed to find anyone talking about sea kale. And yet, this fellow forced crop has all the ancestry and allure of ‘Champagne rhubarb’.

Native to the British Isles and abundant along the North Sea coast, the prickly plant is all but inedible until darkness turns its metallic-purple leaves a nutty, pale yellow, with a taste likened to asparagus.

“In the 19th century, sea kale was the perk of the fisherman’s wife, and in spring, she would cover the plants in shingle and when the tips began poking out, cut them and sell them at market,” says Sandy Pattullo, from Eassie Farm in Angus, who has been forcing sea kale for 30 years and is now the only remaining producer in the UK. “We grow them from our own thongs (bare root plants) over the summer and cut off the roots to use again before placing the tops in trays of compost, adding water and heat and picking from the first week of January to April.”

However, since overharvesting of wild sea kale in the 19th century led to a complete ban on picking it, there’s a huge weight of responsibility on Sandy’s shoulders.

While the expert Paske family, from which Sandy originally obtained his sea kale thongs “as an experiment” over 25 years ago, no longer grows it due to pressure from the supermarkets to drop prices, Sandy is now Britain’s only producer of sea kale thongs. So, when one of Britain’s biggest vegetable suppliers, Marshalls Seeds, wants thongs for its seed catalogue, it comes to Sandy.

“In my mind the taste is incomparable: it’s succulent nutty, sweet taste is wonderful lightly steamed with some herbs and melted butter,” says Sandy, whose family has been farming the land at Eassie Farm since the 1600s. “But it’s one of those vegetables that we’ve all forgotten about.”

The future of forcing

Indeed, at the top of this cache of forgotten vegetables, at least in Britain, is Whitloof chicory (known as endive in France). But its modern-day growing environment couldn’t be further removed from its heritage in the gardens of Victorian gentlemen.

At his farm in Holbeach, South Lincolnshire, Brian Read – who has been producing chicory for more than 15 years, and is now the UK’s only commercial grower – starts it off in the soil, but the forcing process is closer to science fiction than natural science.

Packed into plastic trays and grown-on hydroponically in water for three weeks in darkness; harvesting, trimming and packing is all done via a semi-automated process so the plants are only in the light for 10 minutes.

“It was once a seasonal food, but the supermarkets push for availability has meant roots are now lifted and put in cold store for up to 11 months before forcing, and therefore its available 365 days a year,” says Brian. “It’s one of those products the supermarkets want on the shelves but the demand is so much smaller here than it is in other European countries – and as a nation we simply don’t like bitter tasting vegetables.”

Indeed, while many of the clandestine techniques that produce these blanched beauties have changed little over the years, the demand (and therefore the growing) has dwindled.

Rhubarb in particular has had a bumpy ride. When tastes changed and cheaper Dutch imports became available, commercial forcers reduced from around 200 to only 12. But thanks in part to the tireless efforts of growers like Ben, and the formidable Janet Oldroyd (dubbed the ‘High Priestess of Rhubarb’) who secured a Protected Designated Origin status for the precious crop in 2010, the preservation of these ancient skills have the price of the crop have been secured. From darkness comes light.

“Forcing is in my blood,” affirms Ben. “I feel I am the custodian of this tradition and I’m proud to be doing it. If I had my time again, I wouldn’t want to do anything else.”

First published in Great British Food magazine

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