Not sure where you are Dalesman, but In SE London I got a crop last year…. just.
Likewise, the supplied slips were too late, and, likewise, I’ve overwintered my own which is very easy to do. They just sit in a state of suspended animation on the windowcill until March when they start to wake up.
An Asian chap on our allotments advised me that the tubers only form very late in the season and continue to swell up to a week after the top growth may have been killed off.
So this year I am:
1) starting them off early, pinning down the growth to encourage a bigger root ball.
2) starting them off in the greenhouse in big pots until they start going beserk, and
3) going to fleece them at the back end of the year to extend the season as long as possible.
