A confused plant? We eat rhubarb in crumbles, with custard and we make jam with it (rhubarb and ginger jam was one of my mother’s specialities) but actually rhubarb is a perennial vegetable and not a fruit.
Rhubarb has been cultivated for over 2500 years but has become renowned for its “Britishness”. The Yorkshire Rhubarb Festival, in the famous Rhubarb Triangle, where you can hear rhubarb growing epitomises our native quirkiness.
The farmers in the Rhubarb Triangle produce specially grown rhubarb in the dark in heated forcing sheds. The rhubarb crowns, ie the central section of the plant from which the edible stems will grow, have been carefully selected to produce early stems under these conditions. This trick was discovered by accident at the Chelsea Physic Garden in 1817, when some rhubarb crowns were covered with soil overwinter and the resulting stems were found growing earlier than the rest of the rhubarb. This provided fresh food when there was little else growing plus the further benefit of an especially delicate taste.
But the Yorkshire producers took rhubarb forcing to a whole new level and outperformed all rivals, at one stage producing 90% of the world’s winter forced rhubarb. From providing much needed home grown food during the Second World War to being awarded a Protected Designation of Origin in 2010, Yorkshire Forced Rhubarb (Rheum rhaponticum) is a world class vegetable.
Rhubarb is a native of Siberia and positively thrives on cold; you will probably see shoots peeping up through the snow in your garden after Christmas. Rhubarb needs a period of cold to break dormancy, ie to start it growing, and you need it to be at this stage before you can force the plant. A rhubarb crown needs to be at least two years old before you encourage it into early growth this way as the plant uses up a lot of energy.
Those shoots that you see after Christmas should be ok to force, but for a really early crop you need to start the process sooner in the winter. This will be dependent on the weather as a mild winter is not conducive to the amateur blanching of rhubarb. Digging up the crown and putting the rhubarb in the freezer is not an option.
The preparation for blanching begins in autumn, when you clear away the dead foliage, exposing the rhubarb crown to the frost. In a dry autumn you may need to water the plant. Once there are small signs of growth, cover it with a traditional forcing pot or forcing jar. These are convenient as they have a removable lid so you can easily check the growth progress; but an upturned bucket with a stone to keep it in place will suffice. The idea is to create a darkened environment. You should have rhubarb ready to pick by the beginning of March. Once you’ve harvested the sweet delicate stalks, mulch around the rhubarb crown with compost and leave it to recover over the season.
One of the delights of rhubarb is how well it fits into an easy or low maintenance garden, proving that you can grow your own even if you have a busy lifestyle. Rhubarb crowns are best planted between mid Autumn and early Spring; and should not be harvested in the first year but given chance to establish. A popular early variety is ‘Timperley Early’ whilst ‘Victoria’ is a later variety.
Do remember that whilst you can safely compost the leaves do not eat them. Rhubarb leaves contain a toxin which at the very least will give you a stomach upset and at the worst could send you into a coma until next winter. On a ‘green’ note, the toxin is supposed to make an effective rat poison if they’re a pest that you need to get rid of.
This is the time of year (end of January – end of February) for the Yorkshire Rhubarb Festival and there is much useful information on it and on the Rhubarb Triangle here, including how to visit the forcing sheds to hear the rhubarb growing and see it being picked by candlelight.