I wouldn't cut it. Put several inches of grass or leaves around and up to the base. The dead growth helps insulate the plant. Your usual snowfall should suffice for water, but if you go droughty for several weeks, an occasional drink would be good, same as other overwintering plants. Don't make it soggy, but plant roots tolerate damp freezing soil better than dry.
Here are my dormant winter perennials. I leave all the tops on for critters, insulation and visual interest. No Miscanthus in this particular picture, but nearby.
