In article m,
AndWhyNot writes
Hello,

Our friend and neighbour just loves rhubarb (as do we) but has none in
her garden .......... we have lots of the stuff, and promised her a
clump of our root for her garden.

When would be the best time to 'dig up and transfer' a clump ??

Lift the whole root clump out in early winter as soon as the top of the
plant is dormant. Divide into four or five pieces with a spade. The
sections can be replanted then, or they can be left out to be frosted,
but they should be back in the ground by New Year's Day [by Dec. 21st.,
Winter Solstice traditionally] when the plant will begin growing again.

Leaving the roots out to catch some frost is said to increase sugar
levels, thus making future stems sweeter, but that is disputed and it is
optional. For early forcing rhubarb, take a piece of divided root and
pot it up, or plant it in greenhouse or polytunnel soil. As soon as
small shoots appear, cover the plant with a flower pot and it will
produce very early stems. Dispose of the forced root after cropping.
--
Alan & Joan Gould - North Lincs.