In Herefordshire, if it is a green, reasonably large cordy then you may be OK but it is well worth taking out insurance by tying up the crown and maybe putting fleece round it. If we get a repeat of last year (and predictions, for what they are worth, are for another cold winter) then they are at risk. Here on the Yorks coast which normally gets mild winters I lost 5, including 2 green ones, last year. My own fault for complacency. Red cordies, and even more so, variegated ones are less hardy and are certainly worth protecting. Use fleece or curtain netting, not bubble-wrap. It is important for plants to be able to breath and it is usually not the temperature that kills, it is the frost.

Definitely !! Learn from my experience as I left mine out this winter after it stayed out in the snow the previous winter. This time though the frosts were so bad that it suffered such severe damage that it is now just a stalk. It pains me every time I think about it as it had put on loads of growth during 2010 and was looking so good, new shoots appearing at the bottom too...sigh !!!