Hi there, I am new to clematis gardening and bought two CdB about two years ago from an online vendor. It only gets about 6 feet tall each year but blooms quite a bit so I am guessing the location works just fine.

Problem being that each plant only sends up on main vine (leader?) each year and I'd really like more width in the location. I'm toying with with buying a few more ... is this typical to only have one main vine? I would think as with many other vines they would send up several but this is all new to me so I sure can use some suggestions. Thanks!
K