At a time of year when there’s not much fruit to harvest in the garden, rhubarb that has been forced for an early crop is a rare treat. Of course, rhubarb is not technically a fruit but a vegetable, and the part that is eaten is the long fleshy petiole or leafstalk. It is rich in vitamin C and fibre, and it contains reasonable amounts of vitamins A and K, potassium and calcium.
During January, rhubarb is forced by covering the crowns with a forcing pot, large bucket, or anything that will exclude the light. The dormant buds inside the pot are then insulated with straw or dry leaves. Champagne is an early variety that forces well, while Victoria is also good for forcing and is a heavy cropper.
In Yorkshire, rhubarb is forced commercially by growing in forcing sheds, where it is harvested in mid-winter by candlelight.
From late winter onwards, harvest rhubarb stems by pulling them outwards with a slight twist. Pick only the young pink stems, before they become green and thick, coarser and more acidic. Allow plenty of leaves to remain on the plant to continue to photosynthesise and encourage further growth. During a glut, freeze surplus rhubarb by cutting into chunks, open-freezing and then storing in bags. Rhubarb will continue to crop until midsummer, but forced crowns should be left for 2-3 years to recover before they are forced again.
At the end of the season, around mid-autumn, when the leaves start to die back, remove the old foliage and expose the crowns to frost. Divide the crowns every 4-5 years in mid-spring, just as the soil is warming up. Don’t pick any stems from these plants until the second year so that they have time to develop.
Forced rhubarb is mild, sweet and tender and needs less cooking than the main crop. Stew or roast with orange or ginger for an easy dessert.
Rhubarb leaves contain oxalic acid and, in consequence, are poisonous. Exploiting this characteristic, the leaves have traditionally been used to make an insecticide to control aphids on non-edible plants such as roses, and planting rhubarb near aquilegias is said to keep red spider mite away. Rhubarb also deters blackspot from roses, while small pieces of rhubarb included in the planting hole are said to protect brassicas from clubroot.