Gadenin日本語Get the appIt climbs with leaf stalks, so the support must be thin
Clematis has no tendrils, no suckers and no twining stem. It climbs by wrapping the stalk of a leaf around whatever it touches, and a leaf stalk can only make a complete turn around something roughly a quarter of an inch (6 mm) thick or less. Anything fatter than a pencil and the plant simply cannot hold on.
This one fact explains most training failures. A clematis leaned against a wall, a wide timber trellis batten, a smooth metal post or a thick pergola upright has nothing to grip and will lean, slide and end up in a heap. Give it wire, netting with a small mesh, twine, thin canes or the twigs of a host shrub and it climbs unaided.
The practical fix on a solid support is to add something thin over it. Run horizontal wires on vine eyes four inches (10 cm) clear of a wall, spaced twelve to eighteen inches (30 to 45 cm) apart. Wrap twine or thin mesh spirally around a thick post. Fix a panel of small-mesh netting to a fence. In every case the clematis then does the work itself and you only tie in the occasional wayward stem.
| Support | Climbs unaided? | What to add |
|---|---|---|
| Horizontal wires on a wall | Yes | Nothing; space wires 12-18 in (30-45 cm) apart, 4 in (10 cm) off the wall |
| Small-mesh netting or pea netting | Yes | Nothing; the ideal support |
| Wide timber trellis battens | No | Staple thin wire or twine across the face of the battens |
| Thick pergola post or smooth pole | No | Spiral twine or wire mesh around the post |
| Through a shrub or small tree | Yes | Nothing; lead the first stems in on a cane |
| Bare masonry wall | No | Vine eyes and wires; clematis cannot stick to a wall |
Spread the stems sideways, or you get flowers only at the top
Left to itself a clematis sends every stem straight up and flowers at the top, where the growing tips are. The way to get flowers at eye level and below is to make the stems travel horizontally. A stem trained sideways breaks buds along its whole length instead of only at the tip, and each of those buds becomes a flowering side shoot.
Start early in the season while stems are still soft and pliable. Take each new stem and lead it out to the side and slightly upward, fanning the plant across its support rather than letting it bunch. Aim for stems spaced four to six inches (10 to 15 cm) apart across the face of the support. Once a stem has hardened it will snap rather than bend, so this is a job for the growing weeks, done a little at a time.
Check the plant every week or so during the main growth period. Clematis can put on several inches in a week in early summer, and a week of neglect is the difference between a stem you can guide and a stem that has already fused itself into a tangle with three others.
- Lead the first growth off the crown Lean a cane from the base of the plant to the bottom of the support and tie the young stems loosely to it. This gets the plant onto the support instead of flopping on the ground where slugs find it.
- Fan the stems as they grow Spread stems four to six inches (10 to 15 cm) apart across the support, taking them sideways before allowing them upward. Do this while they are soft and green.
- Tie loosely with soft material Use soft twine or fabric ties in a figure of eight, with the crossover between stem and support so the two never rub. Leave enough slack to slide a finger through. Tight ties crush stems and crushed stems are how wilt gets in.
- Bend down a stem that has run away A stem that has bolted for the top can be untied, arched over and led back down while it is still green. It will flower along the arch. Do it slowly and stop the moment you feel resistance.
- Check and adjust weekly in the growing season Ten minutes a week through late spring and early summer replaces an hour of untangling later and prevents most of the stem damage that untangling causes.
Never yank a stem to free it. Clematis stems snap at the leaf joints under very little force, and every break is both a lost flowering shoot and an entry wound for wilt. If a stem will not come free, cut the leaf stalk that is gripping instead of pulling the stem.
Growing through shrubs, trees and other climbers
Clematis growing up through a host plant is how the genus grows in the wild, and it is the easiest form of training because the host provides thousands of thin twigs to grip. It also solves the cool-roots problem, since the host shades the ground. Plant the clematis outside the spread of the host's roots, eighteen inches (45 cm) or more from the trunk, and lead the stems in on a long cane.
Match the vigor of the two plants. A vigorous small-flowered clematis will smother a small shrub within two seasons; the same plant is perfectly happy in a mature tree. A compact hard-pruned type is the right choice for a rose or a modest shrub, because you cut it back to twelve inches (30 cm) every late winter and the host gets a clear season to itself before the clematis climbs again.
Pruning group matters here more than anywhere. A Group 3 clematis in a host shrub is easy: cut it to the ground each late winter and pull the old growth out. A Group 1 or Group 2 growing through a shrub becomes a permanent tangle that cannot be extracted, so only combine those with a host you never need to prune.
Keeping a record of what you tied where
Note when you last checked and adjusted the ties on each plant. Ties left for two or three seasons are a leading cause of damaged stems, because the stem thickens and the tie cuts into it, and that wound is where wilt tends to start. A simple annual note prompts you to loosen or replace them at the same time as pruning.
It is also worth noting how far each plant grew in a season, measured roughly from the crown to the highest tip. That figure tells you whether the support you have is big enough, and it is the number you need when deciding which host shrub or which section of fence a plant should be given next time you move something.