Clematis over winter

[PPT]

Any advice? I planted a clematis over the summer in a deep wide box which has a trellis up the back. It is positioned in a sheltered spot in front of my shed. The clematis grew like wildfire over the summer and has a nice shape. However, now that it is proper Baltic outside its turned a twiggy brown.

Should I cut it back low? Or leave it? If I leave it will it turn green and healthy again in the spring?

Thanks

[ComeIntoTheMistletoeGardenMaud]

Clematus need pruning at different times, depending on which group they are in. Do you know what variety yours is? Does it have a name?