Vicky wrote

Judith in England wrote:
I always pull up the old roots and start again from seed in the next
year.

I have been reading that you can actually leave the roots to over-winter.

Any experiences? Worth while?

I thought the entire* point of runner beans was to leave the roots in
so that the nitrogen-fixing nodules of the roots conditioner the soil
ready to make it your brassica* bed next year.

Yes that is true, although I'm not sure about the entire point, but usually
the frost then kills the roots so they don't sprout the next spring. In most
areas in most years you would need to lift the roots and store them like
dahlias in order to overwinter them. So then you would have to do without
the nitrogen boost.
Some of us, in more favourable areas, do find that if they don't consign the
roots to the compost bin they will sprout like weeds (where you don't want
them) the next year provided the winter is mild.
--
Regards. Bob Hobden.
Posted to this Newsgroup from the W of London, UK