When we were in our first house in France we had a french man who helped with gardening, building etc. When we needed a new hedge he said just cut bits off the bushes you like and stick them in the soil. Which we did, and it worked. Can't remember what kind they were.
The plants were adapted to that type of soil. And they probably did the work at the best time of the year. And moon.
I don't think early Jan. is a good time.