Hello! I am thinking about putting some clematis on a couple of trellises I just installed. The area is very visible from our sunroom so I'm having second thoughts about the look of the brown clematis vines all winter on the pretty new trellis. Is there any reason I can't cut back clematis in group 3 in late fall? Or possibly cut most of it back in fall and the rest in spring? I wouldn't think any in groups one or two would work for that? Thanks!

Only reason I can think of is that the woody and quasi-woody plants do store vital stuff in the stems and cutting them in the fall removes that and can impair winter hardiness --at least in my experience doing so vs not doing so.
I would think with the group 3, you could cut them back quite a bit some time after the first freeze though, so you wouldn't have to look at a tangle of brown all winter.
There would be no point trying that with group 1. Some in group 2, maybe, the vigorous ones that will bloom on new wood.

Thank you so much!