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 January/ Februrary, mulch around them (not over the crown) to warm and protect them. Farm yard manure makes the best mulch, but some growers like to use other mulching products like straw, leaves or compost.
If you want an early crop pop a rhubarb forcer on top of the crown and mulch around the outside of the pot. The crown doesn't want to be overly wet or it 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. The 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 or they get tired.
Old rhubarb 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.
Rhubarb varieties available online:
Other varieties also available from Preston Bissett Nurseries: