oddballdave wrote:
Rhubarb needs a period of cold to start its growth cycle.
If you lift a crown before Christmas,
let the first frost get to it,
then replant it.
If you cover two crowns (this one and another)
when you eventually get to harvest the forcings
the 'frosted' crown will have had an earlier start, so will have the
better harvest.
http://www.rhubarbinfo.com/rhubarb-growing.html

Thank you kindly. I've never done anything to my rhubarb, see.