In article ,
Charlie Pridham wrote:

Nick, I dont let my pot fulls dry out completely and of course most are
outside in the wet ground, what we find is they are normally OK but
after a hard frost event (-9c or worse) the tubers near the surface go
to mush and the plant takes a season to recover, remembering to give a
generous mulch in the winter avoids that problem.

Thanks to both of you. If it's a serious winter, mulching isn't a
solution here, as the ground freezes at least an inch or two down.
In the 1980s, it was 6", fairly regularly. I shall try to keep them
dryish but not dry and buried in the soil in the polytunnel.


Regards,
Nick Maclaren.