I was tickled to hear from so many fellow clematis lovers about their passions for the perennial climber that splays such scrumptious flowers. I also heard your confusion over pruning — the when and how-to of it. Do you cut the vine to the ground in the spring or only back to the emerging buds or not at all?
When you start researching the pruning of the clematis vine, you can quickly become overwhelmed with all the info out there, but I think I finally got it figured out and the most comforting part is that you really can’t get it terribly wrong. The worst that will happen is you won’t get flowers for a season.
The kindest cut
The first important pruning of the clematis comes in its first and second growing season in the ground. Don’t skip it. Clematis are deep-rooted plants and the roots and top growth need to develop at the same rate for future plant success. The first summer, keep the vine at 18-inches. The second summer, 24-inches. This sends the growing energy back to the roots and your patience will result in full-flowering, robust vines. Cutting back a new plant is always tough, but it really is in its best interest. Also, when planting your clematis, plant it deep, with even the first set of leaves below the soil line.
Clematis are divided into three pruning groups: 1 (A), 2 (B) and 3 (C). 2 or B is sometimes subdivided into two more, 2A and 2B, but this is of lesser concern. When you purchase your clematis, most tags tell you the pruning group or a quick internet search will tell you.
Pruning group 1 (A): Almost no pruning
These clematis bloom on old wood — prune only the dead foliage and stems in the spring, back to the emerging buds. Generally, they bloom early in the season and then they are done. If the vine needs cutting back, do so right after blooming. You don’t find a lot of zone 4-reliable (home of the Garden Drama test garden) clematis. ‘Etoile Violette’ is one.
Pruning group 2 (B): Some light pruning
These clematis bloom on both old and new growth, both early and then sometimes again later in the season, making them a bit of a pain to prune (and to try to figure out). These are the large-flowered hybrid clematis, though the second wave of flowers are usually smaller. Cut out only dead material and spindly shoots back to the strongest buds in the spring. Includes: ‘Daniel Deronda,’ ‘Carnaby,’ ‘Belle of Woking,’ and ‘Niobe.’
Side note: 2a blooms in the spring and sometimes again in the fall. 2b blooms in the spring and then sporadically through the summer. All group 2 clematis bloom on old wood, so across the boards, light pruning is the way to go. 2b also bloom on new growth and as with many perennials, deadheading will result in the likelihood of later season blooms. But the bottom line of 2 or B clematis: prune only the dead and spindly vines in the spring and you will be fine.
Pruning group 3 (C): Hard pruning
The easiest to prune, these clematis bloom on all new growth and can be cut back to 8-inches or so in the spring. Coax the emerging vines onto the trellis as they grow. Includes: ‘Pink Fantasy,’ ‘Rooguchi,’ ‘Comtesse du Bouchaud,’ ‘Avant-Garde,’ and ‘Jackmanii superba.’
A few more tips for happy Daniels and Comtesses and Belles and Ernests:
- Clematis are heavy feeders, so fill their planting holes with rich compost and organic matter and sidedress the plants with compost a couple of times throughout the season. You can also fertilize with 10-10-10 if that is your thing.
- Shade the roots, shade the roots, shade the roots. With mulch or other perennials or annuals.
- You can push some clematis into doing okay in part shade (‘Comtesse du Bouchaud’ seems to do fine, from my experience). But overall, as much sun as possible seems to produce the real beauties.
- The trellis: From my experience, the more vertical and horizontal rungs and slats and poles a clematis has to hang onto, the happier it will be. A little coaxing of the vines to climb and reach to the trellis is usually in order.
- If you experience clematis wilt, see how I dealt with it successfully.