A clematis can live for decades, so half an hour of careful planting is well invested. Many problems blamed on the plant, from slow starts to sudden collapse, trace back to a dry, shallow hole tight against a wall.
When to plant
The RHS recommends spring or early to mid-autumn, when the soil is workable and moist. Container-grown plants bought in summer can go in too, if you plant promptly and keep them watered. Avoid frozen, waterlogged or bone-dry soil.
If you buy a small plant in a 7cm pot, the British Clematis Society suggests potting it on into a 2–3 litre pot and growing it on first; larger plants can go straight out.
Choosing the spot
Clematis like their heads in the light and their roots cool and moist. Most need sun or partial shade, and evergreen and winter-flowering types want shelter from cold winds. Shade the base with low planting, flat stones or a nearby shrub; for a shady wall, see our guide to clematis for north-facing walls.
Distance from walls and fences
Soil at the foot of a wall is far drier than it looks, because the wall and any roof overhang cast a rain shadow. Plant the rootball out from the base and lead the stems back to the support along a cane. In a tree or large shrub, plant on the windward side so that rain reaches the roots.
Planting distances
Preparing the hole
Clematis grow best in deep, fertile soil that holds moisture but drains freely. On heavy clay or thin sandy soil, dig in leaf mould or well-rotted manure before planting.
How deep to plant
Large-flowered hybrids, both early and late summer flowering, go in deeper than they sat in their pot. Buds on the buried stems can then produce new shoots if the top growth is damaged, whether by a careless boot, a slug or clematis wilt.
The RHS and the British Clematis Society give different depths; either is reasonable, but on heavy, wet soil err towards the shallower figure. Other types, including winter- and spring-flowering and evergreen clematis, C. viticella, C. tangutica and herbaceous kinds, go in with the top of the rootball just below soil level.
How deep to set the rootball
Step by step
Planting step by step
- Soak the rootballWater the plant well in its pot; the British Clematis Society suggests soaking it for around 30 minutes.
- Dig deep and wideMake the hole at least twice the depth and width of the pot, then fork over the bottom.
- Enrich the baseMix in compost, about a third of the hole's volume, with a little bone meal.
- Tease out rootsGently loosen any roots circling the rootball.
- Set the depthPlant at the right depth for the type, angled slightly towards the support if away from a wall.
- Backfill and waterFirm the improved soil gently, water thoroughly, let it drain, then water again.
- Cane and mulchTie the nursery cane to the support, then mulch, keeping a few centimetres clear of the stems.
Supports
Clematis climb by wrapping their leaf stalks around anything thin enough to grip, so they need wires, mesh or trellis rather than a bare wall. Fix trellis on battens so air moves behind it and the leaf stalks have room to twine. Tie young stems with soft twine in loose figure-of-eight loops; plastic twist-ties can cut into them.
The first prune
It feels brutal, but a hard first prune gives a bushy plant with several stems rather than one long, bare stem. The RHS advises cutting all stems back to 15–30cm, just above a bud: immediately after spring planting, or the following February or March after autumn planting. Pinching out the tips of new shoots encourages further branching.
For plants not yet in growth, the British Clematis Society offers a gentler option: cut back by about a third. After the first year, follow the routine in our guide to clematis pruning groups.
Aftercare in the first year
Water new plants at least once a month in the first year, says the British Clematis Society, and more often in hot, dry weather. The RHS advises watering deeply, to about 30cm down; in the ground that can take at least four watering cans per square metre.
Don't worry if first-season growth is modest. Clematis put early energy into roots, and a plant that sulks in year one often grows away strongly in its second or third.
Common planting mistakes
Most failures come from a handful of avoidable slips. Run through this list before you walk away.
Avoid the common mistakes
- Not planted tight against a wall
- Large-flowered hybrid set deeper than its pot
- Base shaded from hot sun
- Soft twine ties, no wire or plastic
- First hard prune done or planned
- Watering planned for the first summer
Plant in spring or autumn, 30–45cm out from walls, in a generous, enriched hole; set large-flowered hybrids 5–7.5cm deeper than in the pot (other types just below soil level); then cut back hard to 15–30cm and water deeply through the first seasons.
Sources
- How to grow clematis (RHS) — Planting times, distance from walls, planting depths by type, supports, first-year pruning and watering.
- Growing (British Clematis Society) — Hole size, deeper planting for large-flowered types, soaking the rootball and first-year watering.
- Clematis pruning: group three (RHS) — Hard pruning of newly planted clematis to about 30cm in the first spring.