Nothing for the moment - wait till late March (depending if its still freezing or not) and see if it starts growing - at that point you can remove any dead or dying leaves. This last winter was unusually cold, so if you're worried in future years, you'll have to do the protection thing, which is to pull all the leaves up to the top, tie them in 2 or 3 places and wrap fleece around them to protect the growing tip.