Forced rhubarb uses the energy stored in the root for growth, instead of sunlight like most plants do.
"Yields when forcing rhubarb indoors are influenced whilst the root lives outdoors, thus giving ideal growing conditions whilst outdoors, the plants' ability to store excess energy is increased, but it doesn't matter how much energy store you have, without frost, the plant can't grow and yield correctly."
The roots live outside for 2 years, where they build a carbohydrate energy store in the root. To do this the outdoor crops for forcing are never harvested.
"Outdoor grown rhubarb can be tough and sour, by blocking light in the forcing sheds and growing from the plant's own energy store, it will result in a very tender much sweeter tasting crop," according to Janet. “It’s only rhubarb, asparagus and chicory that can grow in this way out of season."
A lack of frost delays the start of the forced rhubarb season. “We know exactly how much frost each variety needs, so if we’re late getting it, we’re late starting. The last 2 years, growing conditions weren’t perfect outdoors, the forcing roots have not stored as much energy as required and frost levels have been poor, logically yields will suffer."
"Rhubarb is a native of Siberia, so it does not like growing for long periods. Because of climate change the plants grow for longer. Last year, we had a very early spring and mild autumn, so the rhubarb was growing outdoors for a long time, which weakens the root. Healthy vigourous roots result in higher yields of quality rhubarb.”
“This is why we only harvest our roots for a maximum of four or five years, then we destroy them. Some producers keep them much longer, but this risks lower yields, virus contamination and even root death."
Forced rhubarb is usually harvested from January until the end of March nowadays. In the 1950s the season was much longer, from December to April, and plants had their much preferred longer dormant period.
“In 2014 we had a wet, early spring, although rhubarb likes moisture, too much can cause crown rot. We weren’t flooded here, but some growing regions in the UK were. The yield of Timperly Early,( which is on the market at the moment) is down between a third and a half. Yorkshire Growers are saying they can’t remember a year like it for yields.”
However, Janet hopes this will not continue throughout the season, as it is usually the early varieties like Timperly Early that are affected most by climate change.
At the moment, E.Oldroyd & Sons is expecting to harvest 150 tonnes of forced rhubarb this season, down from their usual 200 tonnes. The yield of the outdoor production remains to be seen.
For more information:
E.Oldroyd & Sons
Tel: +44 113 282 2245
Email: janet@eoldroyd.co.uk
www.yorkshirerhubarb.co.uk