On 05/07/2013 18:16, Bob Hobden 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?

Yes, we tried it one year. Lots and lots of sprouts but they didn't seem
to crop as well as fresh planted ones, seemed to lack vigour. We never
repeated the experiment.
In a very mild area it would be possible to leave them in the ground and
let them grow every year, say, up a fence, where they make a nice
backdrop to a flower border.

The old idea was to lift and pot some of the roots/tubers then start
them early in the season, they don't give much of a crop but they are
earlier than the seed raised plants, and in the days when "The Big
House" wanted anything early or out of season then every little helped.