Synonymous with and sometimes sold as C. maximowicziana, C. paniculata and C. dioscoreifolia, although technically C. paniculata is a separate species native to New Zealand. Clematis Paniculata Care Size & Growth. Winters are just too cold for most seedlings, and you can pull whatever takes root easily enough. Clematis paniculata (Sweet Autumn Clematis) is listed in the Invasive Plant Atlas of the United States. The fast-growing deciduous Sweet Autumn Clematis vine is winter hardy to USDA hardiness zone 4. According to the U.S Forest Service, Invasive species have contributed to the decline of 42% of U.S. endangered and threatened species, and for 18% of U.S. endangered or threatened species. Check the leaves! Sweet autumn clematis is not particularly invasive if you live in Zone 5 or further north. That being said, this plant grows like gangbusters when you stick it in the ground. Small, pure white flowers emerge in August and September and by … Native or Invasive Clematis? This perennial vining plant hails from Japan, and with its rapid growth and abundant, fragrant flowers, it is a popular addition to the summer garden around the world. Sweet autumn clematis can aggressively self-seed in the landscape, and has escaped cultivation and naturalized in many parts of the U.S., particularly in the East and Midwest. The native virgin’s bower (Clematis virginiana) is in full bloom in Indiana from August to September, looking like a blanket of white flowers spread over other vegetation.After blooming, numerous pistils with feathery styles give the fruit a fluffy appearance. Sweet autumn clematis (Clematis paniculata, Clematis terniflora) is one of the late-blooming clematis vines that features not only flowers different from most clematis, but also an unusually heady scent.