Rhubarb has seen somewhat of a revival in the last 10 years and sales are steadily on the up due to its health credentials and fashionable status, both in restaurants and at home. Its attributes are not a new discovery - native to Siberia, rhubarb was first found in 2700BC and its roots, which are poisonous, were used as medicine. Known for containing oxalic acid, it was also used as a cough medicine until the last century and Henry VIII was apparently dosed up on rhubarb for most of his later life.
The process of forcing rhubarb first came to Yorkshire in 1887 after the system was discovered 70 years earlier at Chelsea Physic Garden in London. The method, found by accident, was created when workmen dug a trench in the area where the facility was growing rhubarb and left the mound of soil on top of old rhubarb roots over the winter period. When the plants were discovered, the soil had protected the rhubarb from the cold, and the dark had made the sticks tender and ready to eat long before the UK season started in April.
Today, the process has been developed into an efficient, yet simple, system in which rhubarb roots are prepared outside for two years, taking in nutrients and, through photosynthesis, storing glucose. By not harvesting any sticks from the plant, it is allowed to store excess energy produced in the root in the form of carbohydrate. The roots flourish in Yorkshire’s favourable conditions and grow quickly into huge systems that are packed with stored energy.
The plants require a minimum of two summers to store sufficient energy and not a single stick can be harvested at this time, so all outdoor crop is lost in its preparative years. In the winter of the crop’s final year, measured amounts of frost are necessary to convert the carbohydrate energy into a glucose form the plant can access. This will enable the plant to grow when photosynthesis is prevented in the dark forcing sheds.
Once sufficient cold has been recorded, the roots are carefully moved from the field to forcing sheds where they are tricked into growth with the aid of water and heat.
It takes five to six weeks of careful control to get to the first harvest. From then on, the process is fast-paced and rhubarb sticks are harvested every five days until the root is depleted of its energy, which is usually after four to five weeks of harvesting, when the root dies.
Known in the media as the ‘high priestess of rhubarb’, Janet Oldroyd Hulme runs her family firm from Yorkshire’s infamous Rhubarb Triangle, between Wakefield, Leeds and Bradford, in which some 12 producers grow nearly all the forced rhubarb produced in the UK. With more than 100 hectares of outdoor rhubarb and 10 forcing sheds - including the UK’s largest at 10,000sqft - Oldroyd Hulme’s business is one of the biggest rhubarb producers in the country. Her late father, Ken, who ran the business before her, was awarded the highest distinction from the Horticultural Society for his services to the rhubarb industry.
The Oldroyds have been growing forced rhubarb in Wakefield since the 1930s, and have perfected their method throughout the industry’s highs and lows over time.
This year, Oldroyd Hulme believes that the company’s yield will be back to its former glory of 200 tonnes a year for the forced crop and 800t from the fields, which had become the norm up to a few years ago, before climate change began to take its toll on the forced root system. The forced rhubarb season has started progressively later every year because of the UK’s milder winters, and ends when spring arrives. With spring comes the first of the outdoor crop, which, with careful management, can be harvested until the first cold nights in late September.
“My father used to start harvesting forced rhubarb in December,” she explains, “but I would not have a chance of doing that now. It is not cold enough and the seasons have been shifting. Generally, spring is earlier now, so the forced rhubarb season has been cut off at both ends, because once green top [the outdoor crop] comes onto the market it is much cheaper and many customers switch from forced straight away.”
The roots now in the rhubarb sheds have had a couple of wet, cooler summers, explains Oldroyd Hulme, who says that the weather in the Rhubarb Triangle has been very similar to where the vegetable was first grown on the banks of the river Volga in Siberia. In fact, the contrary weather that has been devastating for most growers in the UK has worked to the forced rhubarb industry’s advantage. “It has been cool and wet, so it has been perfect for the rhubarb roots,” she says. “Elsewhere in the country, rhubarb growers cannot offset the high production costs because the roots are not strong enough to give sufficient high-quality yields.”
The Rhubarb Triangle is situated at the foot of the Pennines in a frost pocket and receives high rainfall. The area’s deep, water-retaining soils are perfect for root development. However, the last three years have seen low yields and a lesser quality because of warm temperatures and low rainfall experienced during the crop’s establishment.
“Our knowledge has been handed down through generations of families within the Rhubarb Triangle, and mistakes can be disastrous financially,” adds Oldroyd Hulme. “When my father was an adviser at Stockbridge Technology Centre (STC), they developed a concept called cold units. It is a system of calculating and measuring how much cold the roots need to access their complete energy stores once in the forcing sheds. Soil temperatures must be a minimum of 9°C to register a single unit and constant soil temperatures of 2°C used to be commonplace in the Rhubarb Triangle in November. These cold units are necessary for the main season varieties Stockbridge Arrow -bred at the STC - along with Queen Victoria, which appears in February. Both varieties require 320 cold units to grow to their full potential in the forcing sheds and complete harvest before the first outdoor sticks appear on the markets in April.”
Oldroyd Hulme has to be sure that the varieties she uses have accumulated the correct amount of cold units prior to entering the forcing sheds, as well as making sure the roots receive the care and attention necessary. Timperley Early, which only needs 130 cold units, is the most common early variety, but its yield is typically much lower than other varieties and is more likely to sport a salmon pink colour rather than the blood-red shade of the Stockbridge varieties. “Timperley Early does not produce the best-quality sticks, but it starts the season and does the job,” says Oldroyd Hulme. “We now need a new early variety to come on the market in December or January that has the same quality and yields as Victoria or Stockbridge Arrow, but without the high cold requirements - a near impossible task. And not all varieties of rhubarb can be forced.”
E Oldroyd and Sons grows Timperley Early, followed by Stockbridge Harbinger, which needs 190 cold units and has a deep-red colour, then Reeds’ Early Superb. The season is completed with the maincrop varieties Stockbridge Arrow and Queen Victoria.
“If we are short of cold units, the energy will not be converted and yields will be low, so we wait as long as we can,” says Oldroyd Hulme. “We are ever-mindful of both the early spring time and our need to empty the sheds of the exhausted Timperley roots and bring in fresh roots to start the whole process again, but it is always a question of time.
“It takes 10 weeks from first filling the sheds to final harvest. To start the process short of cold, or push crop growth with overly high temperatures in the sheds is a recipe for disaster, but we have got to provide continuity. We have to work out which varieties will fit in correctly and contend with Mother Nature’s apparent memory loss of seasonal temperatures. Providing my customers with crop continuity is like planning a military operation.
“A lot of Dutch rhubarb is imported to cover the shortfall. The Christmas market for rhubarb is very slow and it is now, only after Christmas, that people in the UK remember their old friend, so it suits me to start the harvest after the New Year break and it gives us time to propagate and plant fresh roots.”
Like most vegetables, rhubarb can be hit by disease, and Botrytis is a huge problem for rhubarb growers, as it thrives in warm and damp conditions such as the forcing sheds. It affects the leaves of the plant by turning the edges black, making the stick rubbery. “We do not use any pesticides on our forced crops, so it is all about prevention,” explains Oldroyd Hulme. “We carefully wash the roots’ surface once in the forcing sheds, so that the buds on the surface of the root are as clean as possible and free of any fungal spores.
“To lift the roots from the ground, we designed a special machine because ploughing the roots out inflicted too much damage. The roots can easily be damaged at this time, so all the work is done by hand and the roots are lifted onto trailers using heavy-duty, three-prong forks. If a fork pierces a bud, then its future rhubarb sticks will split, making the product either Class II or fit only for the bin. Then correct amounts of heat and water must be applied at different stages of growth. It is a carefully managed crop and secrets have been handed down from generation to generation.”
E Oldroyd and Sons matt the rhubarb roots together in the sheds to form growing beds, which are accessed by paths to ensure that the bud systems are not damaged during harvest. “We still use the phrase ‘fire the sheds’, which means apply the heat,” says Oldroyd Hulme. “This term originates from when Yorkshire coal was used as fuel to heat the sheds. Today, we use propane or diesel. When heat is applied it tricks the plant into growth and buds swell, stretching so tightly that when the first leaf breaks through it makes a slight popping sound. The plant will then draw on its own energy reserves for growth. If it grows too fast then the rhubarb will lose its flavour and colour.”
The company classifies its rhubarb into three grades depending on quality; premium grade, which is sold under the Crimson Crown brand - it is thick and brightly coloured, and mostly goes to retailers and restaurants via New Covent Garden Market; Class I, which goes to supermarkets; and Class II, which is usually made up of thinner sticks, and is sold to caterers and market traders. Product hit the shelves this week under a Yorkshire banner in Sainsbury’s, Marks & Spencer and Asda.
But consumers are not only interested in eating Oldroyd Hulme’s rhubarb; they want to come to the farm and see how it is grown themselves. She has welcomed up to 2,000 visitors to Carlton Village for Rhubarb Tours from January to March for the last 10 years. The tour lasts two hours and consists of a history of the medicinal use of rhubarb, the history of the forcing process and its production today.
“We started the tours just as rhubarb was becoming popular again,” explains Oldroyd Hulme. “As more people became health- conscious, its popularity grew and, while people are concerned about their health, I cannot see its popularity waning in the future.
“With only a few growers in the UK, supply is always going to be limited, but then over-supply nearly destroyed the industry when rhubarb fell out of favour after World War II. At that time, there were more than 200 producers in the Rhubarb Triangle alone.”
According to Oldroyd Hulme, the rhubarb industry was hit hard when the government curbed the price of the product to one shilling a lb during World War II. As rhubarb was a nutritious and, more importantly, home-grown product, the government decided that it should be readily available to all in the UK; however, this had quite an effect on future generations.
“A lot of rhubarb was grown both commercially and domestically during the war and, as a result, a whole generation became tired of it,” says Oldroyd Hulme. “And after the war, refrigerated transport came in and exciting tropical fruits were coming into the country. Rhubarb sadly obtained a very working class image and buying pineapples instead was very much seen as a mark of status.
“From producers struggling to meet demand, the whole industry spiralled in the opposite direction. In a supply and demand market, the product price plummeted, resulting in many growers going bankrupt. Some sold their businesses and some moved onto other crops. Tragically, forcing sheds went into disrepair and secrets that had been passed down the generations were forgotten.
“Thankfully, my father got through it as he grew other crops as well as rhubarb. He stubbornly refused to abandon the crop he loved, believing that people would return once again to their old friend, and how right he was. Now, tastes have changed and people prefer sharp, tangy products.”
Adding to its popularity, rhubarb’s health credentials have been subject to scientific research, with researchers at the University of Sheffield looking into how the cancer prevention properties in rhubarb are affected when cooked. The vegetable has been classed as a superfood for its ratio of health benefits to calories and it has also been proven that rhubarb speeds up the metabolic rate. Diet companies have latched onto this over the years, making the vegetable a must on all major diet programmes.
Chefs have also taken a big interest in rhubarb over the last 10 years, concentrating on both sharp tastes in savoury dishes and traditional British puddings. Oldroyd Hulme has found that both consumers and caterers have been asking for British rhubarb over the past three years, and that some prefer to wait for the UK season to start rather than buying Dutch imports. “My phone does not stop ringing after New Year’s Day and restaurants in particular are very keen to get started with British rhubarb,” she says. “Dutch product is not quite the same. They have a totally different way of doing things, but it helps ease demand.”
Influenced by her direct consumer contact on her tours, Oldroyd Hulme decided to apply for protected name status for rhubarb from the Rhubarb Triangle five years ago. The decision is currently with the European Commission in Brussels.
“Some of the general public not only do not know the difference between Yorkshire rhubarb and Dutch product, but they do not realise that forced rhubarb is totally different from outdoor-grown product,” she explains. “Some 10 years ago, people started to want to know if produce was British or foreign, but in the last three years the increase in interest has been incredible.
“Of course, supermarkets now put the country of origin on the pack and even specify the producer, but we would love to achieve protected name status and to distinguish it further, which I am sure would help preserve what is part of this locality’s heritage. We are so close to the same fate as the local Pontefract liquorice root production.
“Just as my father was, I am determined that this will not happen to Yorkshire forced rhubarb. But I am beginning to wonder if the high priestess is getting some help above, from her late father, who just might be still fighting the cause by requesting intervention from God, and is giving the frost needed. It would be nice to think so.”
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