I suspect it's a bit late now. However, you won't lose anything by trying, will you? Good luck.

or replant the original plants into pots and cut them back to a couple of inches long. they may resprout if kept frost free and then you can take cuttings in the spring.

Thanks all. My Boxus isn't quite big enough then as yet, and I will take a fewcuttings of my Million Bells Just in case and pot the rest up.