Sweet autumn clematis covers itself in thousands of small white star-shaped flowers in late summer, and the fragrance carries a long way on a still evening. Clematis paniculata climbs 20 to 30 feet and spreads 4 to 6 feet in part sun, hardy from Zone 4 through Zone 8.
Bloom comes in August and September, later than almost any other clematis, and it lasts for weeks. Silvery seedheads follow and hold into fall.
This is a vigorous vine, which is the thing to plan for. It puts on serious growth every season and wants a substantial arbor, pergola, or fence rather than a light trellis. It flowers on new wood, so cut it back hard in late winter, to about a foot, and it will regrow and bloom the same year.
It seeds freely and is considered invasive in parts of the Southeast and mid-Atlantic. Cutting the seedheads off after bloom prevents that and takes only a few minutes.