Maryann, I have some clematis that I prune all the way to the ground (sweet autumn clematis) and others that I leave one to two nodes above the soil line. In the John Howell's book on the viticellas he recommends cutting the viticellas all the way to the ground.

Just like anything else with gardening different things work for different clematis and different people. You will have to see how adventuresome you are and try various techniques to see what works best for you. If you want a conservative approach, leave two to three nodes with swelling buds above ground level when you trim. How tall of a stem that leaves above ground is really going to vary clematis from clematis since the distance from one node to the next can vary from plant to plant.

Soil that is properly amended will drain freely. Mulch can hold moisture against the crown and cause it to rot. That being said some clematis types may be more prone to rotting when wet mulch is left over the crowns. I have quite a few clematis that I have thrown mulch over the entire crown and the plants have survived just fine. It would also depend on the type of mulch since pine needles allow air cirulation much better around the crown than would a lot of wood mulch.

I hope I am not one of the ones who has confused you. I often tell people who are brand new to clematis to cut them 12-18 inches from the ground. That way, they don't have to figure out what or where the nodes/buds are, and it will pretty much take care of pruning without a lot of stress for them. It also seems not as harsh or frightening as cutting them to the ground. Once you have grown them for a while, you tend to figure out what works best for your plants and in your climate. The year my husband stepped on one of my clematis and broke it off at the ground and it came back with a vengeance, I discovered that cutting them to the ground would work well here :-)

Carol