I think what they may be getting at is that you don't need to cut group 3 down as hard as is routinely done. They do bloom on new wood, but new wood grows from anywhere along the vine. If you don't cut it low to the ground, the new wood will be higher up. That may be where you want it. Many people say 'ah, but then you get bare stems at the base...' Sometimes that doesn't matter, or you can cut a few stems lower to provide cover at the base, while leaving most of the new growth higher up. I regularly do not cut back group 3 hard. I just selectively trim some lower stems and leave a lot of the rest fairly long. If there are more/longer stems, there are more places for new growth to rise, making more places for flowers to emerge. More expert clematis growers pooh-pooh my approach but it works for me and I'll keep doing it. I planted a Betty Corning last year so I don't have any relevant experience with that one yet. I know it's supposed to be very vigorous and long-blooming. A few pictures of group 3s not hard pruned: Jackmani Superba that had never been cut back hard for seven years: It'll be interesting to see what that one does this year because it got cut back very hard last summer when we took out the New Dawn roses that shared the arbour with it. The clematis on the chainlink fence on the side is also a Jackmani Superba that gets cut back to the top of the fence (4') each year. I'm not sure what the clematises on the copper fence are - they were supposed to be Huldine, but clearly aren't! They are only two years old in that picture (2010) so are still a bit skimpy. I prefer not to have to do a lot of pruning so most of my clematises are group 2. Last summer we replaced the New Dawn rose swag with clematises. They are a mix of group 2 and 3 but I intend to treat all of them as light/no prune. It'll be a couple of years before I can see if that will work well or not. My experience to date has certainly led me to believe that one does not have to rigidly adhere to the pruning 'rules' to get a showy display and happy vines.

Beautiful!

The empty spot is to the right of Betty Corning. I think Tie Dye would be a better contrast than Mary Rose. There is plenty of room, this photo just shows the top left corner of this wall of lattice. I shovel pruned Princess Diana from this spot because of mildew. She always got it first. I'm hoping maybe the others won't get it now.

Always hope for a Clematis as long as it has good roots. Give it some root stimulator to see if this will move it along. Wait a month & give it another helping of the root stimulator. Or you could go right to the Rose food & give it some fertilizer & see if it takes off. Since the plant had good roots it should come back. I have brought back a few clematis from rabbit damage with the root stimulator & rose food.