The best clematis for containers and how to grow them in pots

You don't need a border to grow clematis. Plenty of varieties will flower happily in a large pot on a patio, balcony or beside a front door, provided you choose a compact type and give it a container that keeps its roots cool and moist.

What makes a good container clematis

The British Clematis Society advises that lower-growing types generally do better in containers, because vigorous clematis use up nutrients and moisture faster. That rules out the giants: some montana varieties reach 6m or more. Look instead for plants that stay within roughly 1–2.5m, flower over a long season and need little pruning or a simple routine.

Compact clematis worth considering

The heights below are the ranges given in the RHS plant database for plants growing in the ground. In a pot, plants are often a little smaller.

'Petit Faucon' (group 3)

A small, upright, non-clinging clematis listed by the RHS at 0.5–1m, with violet-blue flowers up to 9cm across from summer into early autumn. It holds the RHS Award of Garden Merit (AGM), is rated H6 (hardy throughout the UK) and tolerates any aspect. Because it doesn't cling, give it a small obelisk or let it lean on neighbouring plants.

Boulevard series, such as 'Ooh La La' (group 2)

The Boulevard series was bred for compact growth. The RHS lists 'Ooh La La' at 1–1.5m, flowering from late spring to late summer, and notes it does best in partial shade so that its flowers don't fade. That makes it useful for a shady courtyard or a north-facing doorstep.

'Piilu' (group 2)

Pale pink flowers with a darker central bar, usually double or semi-double in the first flush and single later in summer. The RHS gives a height of 1.5–2.5m and lists it for any aspect.

'Frances Rivis' (group 1)

An alpina-type clematis with nodding, violet-blue spring flowers. It holds the AGM, is hardy throughout the UK and tolerates any aspect at 1.5–2.5m. Group 1 plants need little pruning, which suits a pot.

Herbaceous clematis

Non-climbing types such as C. heracleifolia are self-supporting and, the British Clematis Society notes, reach about 1m. They can be cut down to around 15cm above the compost in late November or December.

For a cold greenhouse: 'Avalanche'

The evergreen C. × cartmanii 'Avalanche' produces sprays of white flowers in spring. The RHS rates it H4 and notes it can be grown in a container in a cold greenhouse or conservatory, which helps in colder gardens. Our guide to evergreen and winter-flowering clematis has more on this group.

Taller large-flowered hybrids can be grown in pots too. The RHS notes that 'Arctic Queen', a double white, can be grown in containers at least 45cm deep and wide, though at 2.5–4m in the ground it will need a sturdy support and more watering and feeding than the compact types above.

Choosing the pot

• Size: the RHS recommends a pot at least 45cm (18in) deep and wide; the British Clematis Society suggests at least 46cm in diameter and depth. Depth matters more than it does for most patio plants.
• Material: thick-walled pots insulate roots against summer heat and winter cold. The Society suggests lining plastic pots with bubble wrap or polystyrene.
• Drainage: raise the pot on feet or bricks and put crocks or coarse gravel over the drainage holes. Clematis like moisture but not standing water.
• Support: put an obelisk or trellis in place at planting time, rather than pushing a support into the compost later and damaging the roots.

Compost and planting

Both organisations favour soil-based compost. The RHS suggests a peat-free, loam-based mix such as John Innes No. 2, while the British Clematis Society recommends John Innes No. 3 with added grit for drainage. The extra weight also helps stop a tall pot blowing over. Plant at the same depths you would in the ground (see how to plant a clematis) and finish with a layer of grit or pebbles to reduce moisture loss and keep the roots cool.

If the pot stands against a wall or fence, the RHS suggests placing it about 30cm out, so that rain can reach it.

Watering

This is where most container clematis fail. The RHS advises watering pots most days from April to October and checking them in dry spells through the rest of the year. The British Clematis Society notes that a south-facing, sheltered pot may need watering twice a day in hot weather, and warns that letting the root area swing between soaking and complete dryness stresses the plant and invites powdery mildew. Water until it runs from the base, then let the excess drain away. A saucer under the pot is fine for an hour or two on a hot day, but don't leave the base standing in water.

Feeding

Plants in pots depend entirely on you for nutrients. The RHS recommends an organic, general-purpose liquid feed through spring and summer at the dose on the pack. The British Clematis Society suggests that large-flowered types, which it calls heavy feeders, get a high-potash liquid feed at half strength every fortnight from spring to late summer; smaller-flowered types need less. Each spring, the RHS advises removing the top 5cm of compost and replacing it with fresh. There's more detail in our guide to feeding and watering clematis.

Pests and winter care

• Vine weevil grubs eat the roots of container plants. If a pot-grown clematis wilts even though the compost is moist, check the roots.
• Keep roots shaded with trailing plants or ground cover in the same pot, or stand another pot on the sunny side.
• Move tender types to a cold greenhouse or porch in hard winters. Hardy H6 types can stay outside, but keep drainage clear, because a frozen, waterlogged pot is a real risk.
• After a few years, a plant that flowers poorly despite feeding may simply have outgrown its pot; move it into the ground or a larger container in spring.