Forcing rhubarb in late winter is a technique used to produce an earlier crop of tender, pale stems of rhubarb. It’s easy to do, and whilst it’s not strictly necessary you may find it worthwhile.
Essentially forcing involves blocking the light from the rhubarb crowns. The stems therefore grow quickly as they search for sunlight. All you need to do is cover healthy rhubarb crowns with a large, tall bucket (or a proper rhubarb forcer if you have one) in January. Leave them for 6-8 weeks and then you should have lots of very tender and pale coloured (due to the lack of chlorophyll) rhubarb stems. Once you have forced a rhubarb plant, you should let it recover the following year – i.e don’t force it again otherwise you’ll deplete it of energy.
So, what happens if you DON’T force rhubarb? Unforced rhubarb will be harvestable from late April through to June, once the stems reach about 30cm and the leaves are fully opened. The stems will be pinker, and a little tougher, but they will still be yummy!