A new weed appeared in my garden in Raleigh two years ago. This spring I realized it’s seedlings from my sweet autumn clematis. I hate to give up this beautiful vine, but how else can I deal with the aggressive seedlings?
Sweet autumn clematis (Clematis terniflora) is a perennial vine of Asian origin. It climbs vigorously in a dense tangle of leaves and stems up to 30 feet tall. The blooms appear in August—fragrant masses of tiny white flowers—and are followed by feathery seed heads.
This is where the problem begins. The seeds blow far and wide, and by the following spring, clematis seedlings are popping up by the dozens. Sweet autumn clematis is on the invasive species lists of several states, mostly in the Southeast and mid-Atlantic regions. The Invasive Plant Atlas of the United States has mapped the problem areas on its website.
Prompt deadheading to prevent seed formation is one option. A more practical solution, however, is to replace Clematis terniflora in your garden with Clematis virginiana, a species that is native to the eastern half of North America. The two species are so similar in growth and appearance that they share a common name: virgin’s bower.
Clematis virginiana is also a rampant grower that will self-seed in your garden, although not as aggressively as Clematis terniflora. Most importantly, if any of its seeds blow into natural area, like a stream bank or woods, the resulting seedlings aren’t going to disrupt nature’s balance. —Doug Hall