Lovely colored clematis Judith. Semu is a type III so would respond to being cut back. It blooms on new wood so no problem there. I don't know the rose in question nor how large it or its root system would get so my only concern would be if the pot in question is going to be big enough for the two to happily coexist long term. Generally speaking clematis do not like their roots disturbed once established since they really start putting on major flower displays once they get established. Root pruning every couple of years would be in direct contradiction to what you normally want to do for clematis--that is plant it and let it get established. Any way to get a much larger pot to help alleviate the issue of trying to root prune? Of course, you might need a hand truck or dolley to move the pot into the garage over the winter!! LOL Been there, done that with bringing brugmansias into the garage to overwinter it.

Perhaps someone with experience with roses can clue you in on the root size of the roses in question.

Are the pots just to be able to move in winter? or is there no flowerbed there, all paved or something similar?

I would think that they would be hardy in the ground.

The color combo would be great. A whiskey barrel would be a better choice for pot size.

Compassion and Westerland are both very large roses with extensive root systems. I grow Westerland as a large bush and I do mean LARGE, like 10 x 6 ft. I know that you are much cooler than we are and I suspect that you are bringing them in because of a hardiness issue? Either way, there just isn't enough room in a 22 inch pot for a clematis and a climber. Both of those climbers bloom on new wood so you could certainly cut them back to bring them in and then get blooms the next year. Could you put them in seperate pots and place the pots close together? The clematis will climb the rose as long as it is close enough to get a toe hold :-). Then you could root prune the climber if needed and leave the clematis alone. Clems don't like that....I'm not sure what the hardiness ratings for Westerland and Compassion are but I think that they would do well with some protection if you go ahead and put them in the ground. I know that clematis are hardy in your zone.

Carol

Thanks so much for all the advice. The space is paved, so I can't plant them in the ground (there is a strip of soil maybe 10 inches wide by four feet long by the wall further down the path, but for sure that isn't wide enough for those plants. I usually stick some annuals in there.)
Nckville: It's a miracle, but somehow I tip them and sort of roll them out to the garage - takes a while though!LOL I'm pretty strong, so I used to try and lift everything, but there's only so much the old back can take!
Buyorsell & carolfin: your suggestions of a whiskey barrel or two separate pots sound like the best option, if I can't root prune the clematis. I really have no room in the ground for the rose, so that will have to stay potted, but if the clematis struggles, there's always room for one more in the garden, somewhere....:) Thanks, everyone.
Judith

Judith do I ever know what you mean about tip and roll!

A Whiskey Barrel is what you need..and yes I have climbing rosa "Polka" planted with two clematis.."The President" & "Mrs. Cholmondeley"...I also have a drip system on them since they are away from my sprinkler system...Jeanne

Sorry I'm late responding, but I was away for a couple of days.
Nckvilledudes: Yeah, I'm sure all of us do the same crazy, foolish things to our backs all in the name of gardening:) The tip and roll is one of the more sensible stunts I pull LOL It's all worth it, though, eh?.

Hi Jeanne: So glad you came on! It was your photo last year that gave me the idea of a blue clem/orangey rose. You posted it on the gallery and I just kept going back and looking at it. I just saw it again on the Rose forum. Thanks for the inspiration! I will first check around for a whiskey barrel, and if I can't find one, then I'll have to go with the biggest pot I can find. All I could find around here this spring are those mini barrels, maybe 18" across, in unfinished wood. I would love to find the real thing, although I may have to pay an arm and a leg for it! Unless, of course, I can find one at a garage sale. Thanks to all for your advice, and thanks Katefisher, for letting me bud in here~
Judith

Yep Judith it certainly is! :)

Sorry....I believe that should be "butt in here".....
Judith