Re: Rooting plants from cuttings . . .
Cookie . . . You got me in a pinch there. My experience is almost completely with tropicals. I root any time of year, any plant. Little experience I have with temperate climate plants is that of cource they will root from active groth vegetation, and I would think better than from dormant.
Once the plant has had its system shut down from cold I would think dormant branches would respond to rooting as if they had just discouvered Springtime ! An important reason for leaving "just a little foliage" on the cuttings is that some limmited transpiration keeps the cutting alive untill rooting can support it. With dormant cuttings, I think you may have to allow the normal seasonal rest befor it will respond to new groth ?
If I were in your spot, I would at leat experiment during the winter and if your "sample" cuttings do not root . . . and if they do, then you are months ahead of Nature !! Try with a dormant specie that you know you can root in springtime like Juniper, Viburnum, Forsythia, etc. That way if they do not root, then your question is answered.
Love the Earth, Logos / Wholistic Naturalist / Married / Father of ten Cats / Sexual preference: Anything that moves / French-Greek ancestry / Special interests: Codiaeum (Crotons), Evolutionary behavior / Look to the examples of Nature to understand Humanity.