We have two Clematis vines climbing up opposite sites of our front porch. On the west side is Clematis terniflora, or the autumn clematis, which we put in about four years ago. Deirdre was pruning it in the autumn for the first couple of years and then last year didn’t do anything to it. This year it flowered more profusely than ever before and leaped over to the hanging basket and kept going eastward toward the middle column of the porch. It began flowering about two weeks ago and is at its height right now.
On the east side is Clematis tangutica ‘Gravetye Beauty,’ which begins flowering in July and continues through September. By late September all of the blooms are past, but the seed heads are pretty too in an entirely different way. While the flowers are yellow and hang down like paper lanterns, the seed heads are larger with wiry tendrils forming sub-globular balls. As the seed heads age they become frayed and fluffier.
Back in Rochester we inherited a few different Clematis species. Some were early summer bloomers, large (~3 inches across) purple or white flowers with six petals. I put up something for them to climb on and after a year of hesitation, they really took off. There was an autumn clematis on the front porch of the Rochester house that had stems that must have been two or three inches thick. It might have been there since the house was built in 1920. It was an event when it flowered each fall; it was much more strongly scented than the one we have here in Trumansburg. The smell itself was a sort of a presence; you’d smell it in the house and it would change your mood for the better.
The trickiest thing about Clematis would seem to be how and when to prune them. There are three categories of this genus that are variously referred to as Groups A, B, and C, or 1, 2 and 3, or by bloom date.
Group A includes the species and varieties that flower in April or May and should be cut back soon after they flower, not later than July. Group B includes large-flowered hybrids that often bloom once in early summer and then again in the late summer. They should be pruned in February or March back to the topmost large, plump buds.
Group C include plants that flower from mid June through the fall. Every source of information that I looked to recommended aggressively cutting them back until they are only two or three feet high. As noted above we didn’t do this and it is flowering very nicely.
Clematis (pronounced by CLEM-a-tis, by the way) are nearly all vines (there are about 250 species and new varieties being developed constantly), so you wouldn’t think they’d make the best cut flowers. Last week Deirdre cut a flower-laden branch of the C. terniflora and laid it in a shallow ornamental bowl so that all the flowers were sticking up out of the water like some many tiny lotuses. It was strikingly beautiful and lasted for about three days.
Some people will tell you that Clematis are difficult to grow, but this may be due to a lack of patience or a lack of sunlight on the part of the grower and his site. They like full sun (>6 hours a day). Soil should be rich and well drained with a pH close to neutral (7.0). As they are woody perennials, so they take a few years to get established and may not look like much while they are building a root mass.
Trellises or lattices work well as supports for these vines. They wrap themselves around narrow supports. Our Clematis are actually loosely propped up on porch railings and held against the pillars with some strategic monofilament. They don’t seem to mind. The autumn clematis seems to be growing more rapidly and becoming ligneous and self-supporting sooner than the C. tangutica.