Rhubarb, Rhubarb, Rhubarb!
Try explaining to your Spanish neighbour that rhubarb is pulled, the stems are cooked and the leaves are poisonous and you’ll get some strange looks, I promise you! It’s difficult to even find a Spanish name for the plant, so unknown is it here, but most seem to settle for ruibarbo. But rhubarb does have a long and illustrious past, dating back to 2700 BC in China where it was highly respected for its purgative qualities and to promote a balancing effect on the digestive system. Extracts are also excellent in clearing gall bladder stones and have been used topically to treat burns. It is the mature roots that are ground for medicinal use. The poison in rhubarb stems from the oxalates which are found in all green parts, but in higher concentrations in the leaves. Incidentally, this oxalic acid breaks down rapidly when composted, so there is no danger in adding rhubarb leaves to your compost heap.
Introduced into Europe in the early 1600’s, it wasn’t until the 1770’s that its most famous appearance in tarts and pies occurred. Around 1777 an apothecary, Hayward, from Banbury in Oxfordshire, England started cultivating plants of rheum rhaponticum and produced a purgative of excellent quality. When he died his plantations were bequeathed to his family and, today, in Banbury on the original site, the family still work at rhubarb production. They have extended their scope to encompass rheum officinale too, thus marketing the plant for two distinct purposes.
Rhubarb is a perennial plant that is very cold hardy (plants have been known to survive -20C) and is resistant to drought. Its crop is produced from crowns of fleshy rhizomes. In the spring the edible shoots appear and these emerge in succession as long as temperatures remain below 32C. Once temperatures exceed this, top growth dies down and the plant will go dormant in periods of extreme heat. With declining autumn temperatures (at around 5C) the foliage growth re-starts. The real trick with growing rhubarb in Spain is to keep it as cool as possible during the summer months. It tolerates most soils but does appreciate good fertile soil which is rich in organic matter. It is intolerant to most herbicides, so hand weeding is best and problems with insects are rare. An ideal PH is between 6.0 to 6.8. It responds well to fertilisers, especially well-rotted manure which should be applied in autumn but never cover the crown as this can promote rotting. A spacing of about 1m x 1m is adequate and whilst the plants come into cropping in their second year after planting and can last for many years, top productivity is for a period of around 5 years. After that it is best to start new plants.
Mature plants will occasionally send up flower stalks. If you are growing your rhubarb as an ornamental, then this flowering is quite impressive but, if you want rich pickings, the flowering will reduce leaf vitality so the flower stalk should be cut out as soon as it starts to form. The seeds, if left to mature, will germinate quite quickly but you’ll need to wait at least 2 years for the plants to be mature enough to get some pullings.
Rhubarb is a very tough plant, though it will respond well to good care, fertilising and watering. During the first year after planting, do not pull any stalks; the leaves are needed to nourish the roots and produce stout stems for the subsequent year’s growth. In the second year, harvesting may commence – either cut the stems at the soil line or pull them individually. Cropping is spread over about a four to six week period.
You’ll find that your rhubarb plant will not be as prolific here as in northern Europe but you should certainly get enough pullings to concoct a delicious rhubarb pie.