Want the best rhubarb? You’ll have to force it!
If you want tender, sweet rhubarb, forcing it is the answer. Martyn Cox explains how to establish a rhubarb crown and how to force it under cover
SEVERAL years ago I travelled to West Yorkshire to visit one of the UK’s biggest growers of rhubarb. The crop wasn’t growing in the open ground, but was instead planted in serried rows within long, low, windowless buildings that are known as sheds. A few candles mounted on metal stakes provided the only light to lift the gloom.
The lack of natural light is key to the production of forced rhubarb – a highly prized delicacy that is generally available in shops between January and March. Remarkably, it currently has EU protected status, placing it alongside other British foods such as Cornish pasties and Melton Mowbray pork pies.
Forced stems are lighter in colour, way more tender and have a better flavour than those of outdoor rhubarb, which are not ready for harvesting until mid-spring. I was given a masterclass in picking the stuff – I ran my first finger down the inside of a spear, took hold of the base and twisted it out of the plant.
Despite its association with the North of England, rhubarb actually originates from Siberia, where it stood in the damp soil along the banks of the River Volga. Wild plants were first grown for their roots, which were used medicinally in China as far back as 2700BC. It wasn’t eaten in Britain until the 19th century.
Forced rhubarb was actually discovered by accident at the Chelsea Physic Garden in 1817. Gardeners digging a trench in winter dumped the soil on top of a dormant clump of rhubarb. The stems that pushed their way through the spoilage were found to be delicate and tasty.
Inspired by my visit to West Yorkshire, and the lovely rhubarb fool I rustled up with my pickings, I vowed that I would have a go at growing a crop myself. Some time later I snapped up a crown (essentially a bare-root plant) of rhubarb ‘Victoria’ from a local nursery and planted it on my allotment.
Crowns are usually available for planting between late autumn and early spring, while some nurseries offer pot-grown plants throughout the year. Whatever you choose, pick a sunny, open spot with moist, but free-draining soil. Prepare the ground by digging in plenty of well-rotted manure.
Dig a hole that’s the same depth but a little wider than the crown. Place it in the centre of the hole, spread out the roots and plant so the tip of the crown is just visible above the surface of the soil. Use your fingers to firm the soil around the roots to remove any air pockets.
In my experience, rhubarb is happiest in the ground as it’s a vigorous beast, but it’s still possible to raise it in large pots of John Innes No3 with added manure. Small plants can be started off in 12in (30cm) containers, moving to larger ones over time. An established plant will easily fill a 50-litre pot.
Once planted, avoid picking stems during the first year after planting to allow the rhubarb to put all its energy into building up a strong root system. You can sample your rhubarb the following year by removing a few stems, then up to half from then on, leaving some to keep the plant in active growth.
Those who already have a clump of rhubarb could try forcing it. In winter, pack straw around the crown to keep it
warm and then cover with a traditional terracotta forcing jar, a bucket or an upturned pot, making sure that you block out all light. Keep this in place for at least six weeks before having a peek.
The stems are ready for harvesting when they are about 9in (23cm) long. After they’ve all been picked, remove the cover to expose the crown to light and let new growth develop. Avoid picking any stems for the next two years to allow the plant to recover.