How to prune a Clematis plant? How much gets cut out? Is now the ti

I live in Michigan. My Clematis is around 40 years old & has moved with me. Each fall (late Sept. or Oct.) I cut it back to about 6 inches off the ground. No need to cover. I have it growing on the back fence on a trellis. Once it get's full, I use twin & kind off train it to grow along the fence. (Other wise, it will grow over the trellis & I won't see the beauty of the other flowers.) Everyone compliment's me on it's beauty. I have a Jackmanii (Deep Purple).

I agree with the above. I trim mine down to about 12 inches. I live in Michigan also, so I put chicken wire around it and insulate with leaves. Make sure to clean out leaves in early spring because it sprouts and climbs quickly after that. With the warm weather we've had this fall, mine is blooming again right now! Definitely use a trellis or fence to support it. I also train mine with twine. Mine is lighter purple, Elsa Spaeth.

Depends on the variety....https://www.gardeningknowhow.com/ornamental/vines/clematis/pruning-clematis-vines.htm

Is your clematis a large or small leaf vine ? Do you know what type it is ? Generally larger leaf vines should be cut back every other year and smaller leaf vines should be left to their own devices.