I’m planning an arbor in my garden which will be 6′ wide, 4′ deep, and 6-7′ high. I’d like to plant on one side Clematis ‘Polish Spirit’ . Can you suggest a climber that would go with the Clematis for the other side? The other climber would be in partial shade. Great Plant Picks says that Clematis, with pruning, can be managed to 12′ long. How wide can it get or, a different question, would I need to plant one or two for coverage of the planned arbor? Also if you have other favorite arbor climbers and combinations of climbers I would love to know about them.
There are many choices for combining with your Clematis. Climbing roses are considered a natural companion of clematis and, depending on your color preferences, perhaps something which contrasts with the deep purple would be nice: either white or a pale pink. When you say the other side is in part shade, I wonder how many hours of sunlight it does get. Once the prospective climber reaches the top, will it be in sunlight? You could also plant a clematis of contrasting color or flowering season on that side. There are many books in our library on combining clematis with other plants, such as Companions to Clematis by Marigold Badcock (Master Craftsman, 2000), and Clematis as Companion Plants by Barry Fretwell (Cassell, 1994). There is even an entire book on clematis and roses: The Rose and Clematis as Good Companions by John Howells (Garden Art Press, 1996).
If you like roses but not thorns, you could grow a Lady Banks rose which is thornless, but you would have to keep it pruned (it wants to be 20 feet high). The Northwest-based gardening website, Paghat’s Garden, describes it.
Rosa ‘New Dawn’ is a very popular choice in the Northwest, and is recommended by virtually every local garden writer I have come across. Here is a (non-local!) description from Missouri Botanical Garden.
Another option might be the white variety of potato vine, Solanum laxum ‘Album,’ though it may be a bit tender in cold winters.
Eventually your clematis will cover the width of the arbor, but Clematis viticella cultivars like yours are easy to prune (late winter/early spring) and keep to a manageable size. If you like the idea of having more than one color/plant/flowering season, it’s perfectly fine to add another climber. I would avoid anything that is highly aggressive or rampant (Passiflora, Akebia, Campsis, Clematis montana, and others), as you don’t want to overpower ‘Polish Spirit.’