In article , Alan Holmes
writes

I know it may be a bit early to ask this, but when should I lift the rhubarb
to
allow it to 'frost'?

As decent frosts are few and far between these days, I was going to put it
in the freezer for a while.

If a rhubarb root clump is fairly old, or very large, or showing any
signs of rot etc., it is worth lifting and dividing it whether it gets
frosted or not. That is best done after the plant has become dormant,
i.e. around mid-October/early November. The root divisions need to be
back in the ground, preferably in a fresh place by the turn of the year
[Dec.21,winter solstice traditionally] in order to give them a chance to
make a really early start for the next crop.

The idea of letting the roots become frosted is said to increase their
sugar content and thus give the following year's stems more sweetness. I
personally don't think it does that, but then we prefer our rhubarb to
be really sharp and tangy anyway - not acid though, so we don't attempt
to let them catch frost. The freezer idea might work, though it may be
far too cold for living plant roots to withstand - it is a rather
different thing from freezing ungerminated seeds. You could try one root
division as an experiment to see what happens. I'd say that 24 hours in
at as least cold a temperature possible would be enough.

For really early forcing rhubarb, take a smallish young looking root
division at the same time as above, pot it up in good fibrous loam or
organic compost and keep it in a sheltered place until early to mid-
January. By then the first crinkles of new green shoots should be
showing and the pot should be moved into a greenhouse or conservatory.
Place another equal sized pot over the plant to exclude light and
draughts. New stems should be ready to take in a few weeks. They will
be a bit pale and lacking in flavour, but better than those available in
shops at the time. The forced root should be discarded after cropping.
--
Alan & Joan Gould - North Lincs.