I feel I must mention rhubarb as I was born the the very famous Yorkshire Rhubarb Triangle.
When the Crowns are just starting to shoot. in Januarry/ Februrarry, mulch around them (not over the crown) to warm and protect them ideally with farm yard manure but some like to use other mulching products like straw, leaves or composts and if you want an early crop pop a rhubarb forcer on top and mulch around the outside of the pot. The crown don't want to be over wet or they will rot and the usual fungal problems will occur. A good mulch around the pot will keep the rhubarb warm and it will leach goodness into the roots.
Rhubarb Forcers block out the light and encourage long shoots more quickly than when growing conventionally.
Don't try and force the same crown each year. Have a few and alternate. They get tired.
Old plants do need lifting and splitting every few years. If there is a really long old rhizome tap root in your crown its best cropped off just replant the younger shoots and roots.
Other varieties also available from Preston Bissett Nurseries