Yet another Strawberry Question

Not strictly about the allotment

I have one of these:

http://www.garden4less.co.uk/strawberry-planter-tub.asp?partner=hw


For some of my strawberry plants, has been living in the garden, but will be moved to a new spot on the plot shortly.

Have tried many different "over wintering" methods, and never had much luck

Has anyone else got one? And what recommendations do people have for overwintering it to make sure that all the plants grow again next year?

Thanks