This past year was year 3 for PS and year 2 for BA. PS was purchased in a 4in pot, and BA was from our local nursury and in a gallon pot. It was quite pot bound when I planted it, so I tried to [gently] untangle the roots before I planted it. It was still a little bound, but it was as seperated as I could get it without just chopping off a lot of the roots.

Last summer PS grew to about 8 feet, but BA to only 2 or 3. They have similar growing habits (height, pruning, bloom time) so I'm wondering if they are too close together, or if I didn't get BA's roots loose enough before planting. Should I give them another year, or should I dig BA up this spring and possibly move it over more?

Secondly, you say that the BA was in a gallon pot and that it was very root bound when you purchased it. If you didn't tease the roots apart well enough that could be inhibiting it from acclimating as fast as the PS did even though the Polish Spirit was smaller to begin with.

Thirdly, although I often advise planting the largest clematis that you can purchase, often planting certain smaller clematis, especially ones as vigorous as PS, will get established faster in the native soil than a larger sized slower growing clematis.

As I see it, you have one of two choices. Leave the plants alone and see how the BA does this season. If it is still underperfoming this season, I would dig it up this fall, make sure the roots are still not in a tangled mess from its orginal potbound condition, if so remedy the situation as well as you can even if it means cutting off/breaking up the root bound ball, and then replanting it in the same hole. Insure that the plant is given good nutrition and moisture, and keep it well mulched and see how the BA does over the next few years.