It was quite a few years ago that I last wrote about rhubarb in this column. Then, the words were mainly about keeping rhubarb productive by digging up and dividing old clumps every four to five years. This time, the talk is about forced rhubarb!
If you don’t grow it, this is what you probably think of as ‘rhubarb’, that is, the pale pink stuff sometimes marketed as ‘champagne rhubarb’ in supermarkets. Usually available from the end of December to late March, much of it is produced by specialist growers in the famed ‘rhubarb triangle’ around Wakefield. A certain mystique surrounds the cultivation methods of this Yorkshire delicacy. It’s said the rhubarb squeaks as it grows, and must be picked only by candlelight so light does not discolour the stalks. These are the fanciful bits of what is otherwise a fairly basic production process. Rhubarb clumps grown outside for a few years are dug up in autumn and placed into heated, dark ‘forcing sheds’. Warmth and complete lack of light stimulate rapid growth, providing thin, elongated, pale stems that are more tender, and ready far earlier than any that could be harvested outside.
If you have rhubarb in the garden or on the allotment, it can be frustrating to see forced stalks on sale from not many miles away, when your plants are still in deep dormancy. However, with a little bit of effort, it is possible to do your own forcing. The usual and simplest way, which requires no digging or moving inside, is to cover an established clump with an upturned bin, or large bucket or pot. In the past, special terracotta forcing pots were used. These can still be bought if you’re prepared to splash some cash. Covering needs to take place in December or January. This can give sticks ready to pull in March, but it could be later; it depends on the variety of rhubarb you have.
In the past, I tried this method but didn’t have much success. There are two problems forcing outside clumps. Although covering excludes light and gives shelter, it provides only a modicum of extra heat. As a result, stalks are unlikely to be pullable much sooner than those from uncovered clumps. Worse still, a lack of air circulation and dampness can cause rot. Because of this, I now use a different method more akin to that used by the commercial producers. A mature clump, at least four years old, is dug up in December. This is carefully chopped into several segments with a spade, ensuring that each has a ‘crown’ (visible growing point). These are placed, crown up and a little apart, in a large wooden crate half-filled with old compost inside a greenhouse. Each segment is partly buried, but not smothered, with compost. The crate is then draped with thick black plastic sheeting. This excludes light and accentuates any warmth generated by the otherwise unheated greenhouse. Providing the compost has a little wetness, no watering takes place, which minimises the rot risk.
Most years, this method has produced a worthwhile harvest of forced rhubarb. Although I use a greenhouse, a shed or garage should work just as well. If you don’t have a crate, a good-sized container or bin should suffice, even a large plant pot may do. In most years, the first stalks are ready to pull in late February, up to a month before the first outside pickings. And no, I don’t hear the stalks squeak as they grow, nor do I pick by candlelight, but we’ll leave that for another rhubarb talk…
Add a comment