frost got my jerusalem artichokes

i just got half an allotment and, on my first visit, i was pleased to find i had inherited a huge clump of jerusalem artichokes. a few days later, i returned to cut them down so they didn't get windrocked...only to find all the foliage had turned black due to the cold weather. 
i lifted a few the other day & the seem ok but i was wondering if anyone knew if it would affect the crop? do i need to dig them up & store them?
thanks 

I agree with Nikki, 

mine are still in the ground waiting to be boiled with spuds (and suffer the results !).  If you chop down the stems as winter arrives and lay them over the ground, it keeps the frost off the ground so digging the tubers is much easier.   Cheers,   Tony

I would dig up what you can and either replant a few at a 1-2 foot apart each. That way you should get a fair crop. I usually work on about a dozen plants and that feeds 5 of us quite well. I use them mostly for soup, although roasted is nice too.