You can get months of clematis flowers, but usually not by expecting one clematis to bloom nonstop. The trick is choosing a repeat-blooming variety, pruning it correctly, and keeping the roots cool while giving the vines plenty of light.
For a long summer season, I especially like Arabella, Rooguchi, Jackmanii, Polish Spirit, and Huldine. Depending on variety and conditions, you can have flowers from late spring well into September.
A few things make the biggest difference:
- Give the vine sun, but keep its roots cool. Aim for roughly 6 hours of sun on the upper growth. Put 2–3 inches of mulch over the root area or grow a small perennial in front to shade the soil.
- Water deeply. Clematis doesn’t like repeatedly drying out during summer. Deep watering is much better than frequent shallow sprinkling.
- Don’t overdo nitrogen. Too much nitrogen can produce a gorgeous green vine with very few flowers. A fertilizer intended for flowering plants, used according to its label, is preferable to high-nitrogen lawn-type fertilizer.
- Deadhead repeat bloomers. Removing spent flowers can encourage another flush on varieties capable of reblooming.
- Know its pruning group. This is extremely important. Some clematis flower on old wood, some on new wood, and some on both. Incorrect pruning can eliminate a large portion of the flowers.
A great trick: put TWO clematis on the same trellis
This is probably what I’d do if your goal is a trellis covered in flowers for as much of the season as possible.
Plant an early-flowering/reblooming clematis with a later summer-flowering clematis. They’ll intermingle and look like one spectacular plant with changing flowers.
For example, you might pair a large-flowered May/June clematis with Polish Spirit, which flowers heavily later in summer.
Or, for something softer and more romantic, combine a pale pink/white clematis with a deep purple variety.
One other thing that matters in your area: morning sun with some protection from intense late-afternoon heat can be excellent for many large-flowered clematis. You don’t necessarily need the hottest spot in the yard.
If you’re buying new plants, I can also give you 5 specific clematis combinations for Oregon that would give you flowers from roughly May through September, including a purple-and-white combination, pink-and-purple, and a few that would fit a country garden particularly well. Check the zone you live in, and choose a clematis that’s right for you! Happy Gardening!
