How to grow summer-flowering clematis

These easily grown clematis are disease free, vigorous and full of smaller flowers that appear in the second half of summer. There are three main types - the Viticella Group bred from European species, the Texensis Group originally from Texas in the United States, and the Tangutica Group from Asia.

When to plant a clematis

The best times to plant a clematis are early autumn or spring because the ground will be warm and hopefully moist, allowing the plant to race away easily.

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Where to plant clematis

Positioning will depend on the variety, some prefer full sun while others are happiest in shade. Generally clematis prefer cool roots and moist but well-drained soil. Shield their roots with a slab to keep them cool. Clematis vines take up very little ground room so they are ideal for adding colour and foliage to a small garden.

They can be planted at the base of shrubs, a wall or trellis and a smaller clematis varieties do well in containers.

How to plant a clematis

If you’re planting a clematis close to a fence or wall, make the hole at least 2 -3 feet away if possible (60- 90cm)

Dig a large hole - at least twice the width of the pot in which the plant is growing and half as deep again.

Add some well-rotted organic matter, such as compost or leaf mould, to the very base of the planting hole.

Water your new plant thoroughly before planting.

Carefully remove the plant and the canes from the container and lower it into position (avoiding unnecessary disturbance to the root ball).

The root ball should be at least 3" (7.5cm) below the level of the surrounding soil, if possible.

When the plant is in position, fill the area round the root ball with a mixture which is equal parts soil and John Innes potting compost.

Firm the compost mixture around the root ball and fill the remaining space in the hole with soil. Firm the soil.

Place some more of the organic matter used in the bottom of the hole around the base of the plant - but keeping it away from the plant stem itself.

All newly-planted clematis must be well watered during dry weather. The best way is to gently tip a warmed bucket water on the roots every 3 or 4 days, because most are raised in peat-based compost that can dry out into a hard ball.

Water the plant well and allow the soil to settle. Top up with more soil if necessary.

Spend time undoing the ties and removing the canes. You can train it on a fan of short bamboo canes to start with. The gripple system of supports and wires is easy to use, because the wires can be tensioned easily. The Gripple Plant Support System - Starter Pack is available online.

Clematis viticella 'Polish Spirit'

How to prune clematis

Every clematis is sold with a large label indicating the pruning group - either Group 1, Group 2 or Group 3. Take this label off the clematis as you plant and keep it somewhere safe for reference.

Summer-flowering clematis such as viticella generally belong to Group 3. They flower after midsummer’s day (June 21) but before the autumn equinox (September 21). Group 3 include viticellas, orientalis and texensis groups.

Group 3 produce flowers on new wood and they should be cut back in mid-February, to the lowest shooting buds. Clematis enthusiasts often refer to this as the ‘Valentine’s Day Massacre’.

Leave a foot of stem at the base, by May there’ll be lots of vigorous new growth.

Group 1 clematis do not need to be pruned, and group 2 clematis  should have old stems shortened by a quarter in spring.

Find out more about pruning different varieties of clematis

Taking cuttings

August is the ideal time to take clematis cuttings. Look for semi-ripe shoots that are firm but pliable. Cut a long shoot from the base and cut the stem into 10cm (4in) sections. Make the cut halfway between each set of leaves, not straight underneath the leaves as with most plants. The node (where the leaves emerge) should be in the middle - this is called internodal cutting. 

Put the cuttings in a 50:50 mixture of horticultural sand and compost. 

Water well with tapwater that has been left to stand for a few days - this warms the water and releases the chlorine. Cover the pot with a polythene bag and leave them somewhere shady. Keep the soil moist and pot up when roots appear.

Some clematis varieties can be difficult to propagate, even for professionals. 

Feeding

Feed clematis in early spring with a high potash food, such as tomato fertiliser or rose food.

Pests and diseases

Keep an eye out for clematis wilt on early, large-flowered varieties such as ‘William Kennet’. The foliage flops, but the tell-tale symptom is a series of black lesions within the stems, which are often clearly visible when the stems are cut through. Remove all the affected stems at soil level and destroy them by burning, or binning.

Tidy up any plant debris from the soil surface and, if your clematis survives, make a vow to keep it well watered in every following spring. Cut it out an an early stage if it reoccurs.

Luckily later, smaller flowered clematis, ones that are covered in flower in the second half of summer, rarely suffer because they are bred from a Spanish drought-tolerant species named C. viticella. Their names generally have Vt in brackets afterwards. The star performer is the widely available ‘Étoile Violette’ (Vt), a free-flowering, rich blue-purple with starry flowers in July and August. It was once voted the British Clematis Society’s number one.

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Clematis viticella 'Purpurea plena elegans'

Varieties of summer-flowering clematis

The Viticella group

Viticella means "small vine" and this Spanish, drought-tolerant species contains the most easily grown clematis varieties of all. 

Clematis Viticella produce masses of small flowers in shades of blue, pink, red and white and these slot into a garden easily due to their size. Good in drier gardens. 

All Viticella clematis easy to grow and scramble lightly through borders without flattening their supporters, even when they reach their full height of about 6ft. Flower shapes vary. Some have petals irregularly tinged with green such as the white ‘Alba Luxurians’. Many others have flowers with an asymmetrical twist such as the pink ‘Margot Koster’. 

Some plants have bell-shaped flowers held on long stems and ‘Betty Corning’ is a frilly lilac with pink veining. Others have open stars, such as the grey-blue ‘Prince Charles’ and there are also doubles reputed to have been around for centuries. Most are blue, pink, red or white.

It is often difficult to identify the viticella group purely from the name, but in the RHS Horticultural Database each clematis in the group has a (vt) after the name.

'Purpurea Plena Elegans'
An old cultivar, thought to have been grown before 1629. It was rediscovered growing at Abbotswood, Glos, by Graham Stuart Thomas in the 1960s. It has small, rose-like, clover-red flowers which last for several weeks from late July onwards. One of the best viticellas, it is the most widely grown double. The navy-blue, spikier ‘Mary Rose’ is similar.

'Étoile Violette'
This starts to flower from June and continues apace until September. The dark-purple flowers usually have six tepals, each separated by a wide gap, surrounding cream-yellow stamens. Looks extremely handsome when grown over a silver-leaved weeping pear. Bred in France by Morel in 1885.

'Betty Corning'
This silver-mauve clematis produces masses of sweetly fragrant, bell-shaped flowers on long stems from mid-June onwards. Each consists of four slightly frilled tepals and the new flowers are smaller and darker before they open widely. An excellent clematis for covering a bare fence, in the distance it look blue-grey rather than pinkish.

'Kermesina'
A vigorous, flower-packed viticella which has rich crimson blooms. Each wide, blunt-ended tepal is blotched with white at the base; the rounded green foliage enhances the flower colour. The first flowers can be liberally streaked with green and very twisted. Raised by Victor Lemoine in 1883.

'Polish Spirit'
This dark violet-purple clematis is a useful companion for rambling roses as it begins flowering in mid-July, clothing the spent rose with flowers. The flowers, which often have four wide tepals, have a dark middle. Raised by Brother Franczak in 1984.

'Royal Velours'
Less vigorous than most viticellas, but the velvet-textured flowers, more wine-red than purple, have overlapping tepals which form a round, compact flower. Bred in France by Morel in 1900.

'Alba Luxurians'
One of the daintiest of the viticellas and not as vigorous as most. The first flowers can be completely green, but as the season wears on they become white with green tips. Each small, irregular flower has dark stamens and moves on a long stem. Bred by Veitch & Son, Exeter, in about 1900.

'Madame Julia Correvon'
Dark buds open to produce twisted wine-red flowers with ruched, narrow petals which gently recurve. The lime-yellow stamens are informally arranged and the mixture of different flower shapes - from four-tepalled to six - adds to the charm. It grows well in shadier conditions and is free-flowering from early July. Bred in France, by Morel, in about 1900; rediscovered growing at Hidcote.

'Huldine'
A pearl-white clematis which flowers from mid-summer until the end of August. Not as vigorous as some, but the flowers have six tepals arranged in a gently curved flower that frames greenish-white stamens. Raised in France by Morel and grown at Gravetye Manor in the early 1900s.

‘Chatsworth’
A very new variety with masses of dainty, pearly-blue hanging flowers have a slightly darker bar at the centre, a lightly textured surface and the tips of the petals gently twist.

‘Burning Love’
The newly bred clematis with vibrant-red, textured tepals that gently recurve to reveal twisted tips set round a crown of contrasting yellow stamens.

Clematis texensis 'Princess Diana'

Texensis Clematis

These are often called tulip-flowered clematis due to their tubular, upward-facing flowers. They enjoy summer moisture and are not as easy as the viticellas - but still well worth growing. Most come in shades of deep-red and pink. They’re generally short climbers, with an almost herbaceous tendency, and they do best in warmer gardens with good soil. Hard winters have been known to see them off.

‘Princess Diana’
One of best, with deep-pink trumpet shaped flowers with paler mauve-pink margins.

‘Duchess of Albany’
A clear-pink classic variety that flowers well, with trumpet-shaped flowers edged in paler pink.

‘Gravetye Beauty’
Named after the Victorian gardener William Robinson’s Sussex garden. He championed these smaller-flowered varieties. This has rich-red trumpet shaped flowers have paler mauve-pink margins.

'Étoile Rose'
Smaller nodding blooms from July or August, through to October time The pink flowers hang down vertically, showing a pale silver-pink edge, on this veteran French variety bred in 1903.

‘Princess Kate’
This recently bred clematis is ideal for a small tripod on a patio. The purple-pink flowers are edged in white’ Less floriferous than many though. Orientalis Clematis (also known as the Tangutica Group_ These yellow-flowered clematis have thick tepals and fluffy seed heads. They cover large areas, but dislike laying wet in winter so a layer of grit underneath the root ball will help. It’s often raised from seed, so can be variable. Go for a named form that’s propagated from cuttings, or use a clematis specialist. Tangutica is a sub species.

‘Bill Mackenzie’
Spotted in 1968 at Waterperry Gardens near Oxford by Bill Mackenzie who was then Curator at the Chelsea Physic Garden. The bright yellow nodding, lantern-shaped flowers are larger than most, with distinctive dark reddish-brown stamens. Silky seed-heads follow. Needs space.

‘Lambton Park’
Named in the early 1980s, after the garden centre where it was found, this has the largest flowers of any yellow Tangutica-type clematis. It’s less vigorous, flowers earlier and the flowers are said to have a coconut scent.

Clematis 'Dr Ruppel'

Other varieties

'Dr Ruppel' (syn. 'Doctor Ruppel')
Mauve and red bicoloured flowers that bloom from May to September. Suitable for partial shade and for growing in containers.

'Duchess of Edinburgh'
Large pom pom-like flowers that bloom in early summer with a second flush in late summer/early autumn. Suitable for any aspect and for growing in pots.

'Hagley Hybrid'
A shade-loving clematis with pale pink flowers with contrasting white and dark pink stamens. Compact and vigorous with a long blooming period from June to August.

'Niobe'
A rich deep red clematis that flowers from mid to late summer. Fluffy seedheads in autumn provide added interest. Grow in full sun or partial shade.

'Piilu'
Delicate pink flowers that can be double blooms or single on the same stem. Flowers in early summer and again in autumn. A compact variety perfect for pots.

'Warszawska Nike' (syn. 'Warsaw Nike')
Deep purple blooms with contrasting yellow stamens that bloom from mid summer to early autumn. Ideal for containers and small gardens or balconies.

'Westerplatte'
Blood red flowers that bloom in early summer and again in autumn. Grow in sun or partial shade.

'Yukikomachi'
Blooms semi-continuously from late spring to mid autumn with elegant pale blooms with a subtle lavender/blue colouring.

'Rebecca'
Clematis 'Rebecca' is a striking deep red variety with white anthers. Grow in sun or partial shade.

'Sunset' AGM
Clematis 'Sunset' has large, showy flowers (15cm in diameter) in a deep plum colour streaked with red. A compact variety that's well suited to containers.

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