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How to…prune clematis

by Rhiannon James

clematis_pruning

Pruning, or cutting back plants to keep them in shape, is one of those jobs where it really pays to check before you chop as recommended timing and approach can vary enormously between different plants.

Clematis, for example, fall into three basic groups based on when they flower, and each has its own specific pruning requirements.

There are several reasons to clip: it will help to keep plants growing and flowering strongly; stop them becoming lanky or outgrowing the available space and it can also help air to circulate, reducing the risk of fungal diseases. Removing weak, diseased or dead stems will also help to stop any nasties spreading to the rest of the plant.

The Flowering Gallery

Group 1: the early birds

The early birds flower from late winter to late spring. They don’t usually need regular pruning once they are established but they can be thinned out, trimmed or cut to shape as needed.

Early flowering clematis

Clematis alpina and hybrids

C. armandii

C. cirrhosa

C. macropetala

C. montana

If you find you do need to prune them, cut back stems immediately after flowering – this will allow new growth to form and ripen in time for the next set of blooms. Cut stems back to just above a pair of healthy buds. Any vigorous shoots that spread too far can also be cut back through the summer. Occasionally, you may need to cut clematis from this group back hard to rejuvenate the plant. After flowering, cut stems back to 15cm from the ground, just above a pair of healthy buds. The plant will take some time to recover so you should do this no more than once every four to five years.

Group 2: the lazy, crazy, hazy days of summer gang

This group includes most of the large-flowered clematis. They flower from May onwards and many produce a second flush in late summer.

Summer-flowering clematis

Clematis‘Elsa Spath’

C. ‘H. F. Young’

C. ‘Henryi’

C. ‘Mrs Cholmondeley’

C. ‘Marie Boisselot’

C. ‘Nelly Moser’

C. ‘The President’

C. ‘William Kennett’

clematis_0918All of these clematis flower on shoots from the previous season’s growth initially so you’ll just need to gently trim back stems in late winter or early spring to encourage vigorous new growth that will produce better flowers. Working downwards from the end of each stem, cut just above the first pair of healthy buds, removing any weak, damaged or dead material.  This group of clematis also benefits from a second trim of some stems after flowering to encourage another flush of blooms later in the season.

Alternatively, this group can be hard-pruned every three or four years in late winter – cut stems back to about a metre from the base, just above a pair of strong leaf buds.

Group 3: the last arrivals

In this group are clematis which flower from mid-summer into the autumn.

Late flowering clematis

Clematis ‘Duchess of Albany’

C. ‘Ernest Markham’

C. ‘Étoile Violette’

C. ‘Jackmanii’

C. ‘Perle d’Azur’

C. ‘Rouge Cardinal’

C. ‘Star of India’

C. texensis (‘Etoile Rose’ etc)

C. ‘Ville de Lyon’

C. viticella

These clematis flower on the current season’s growth and respond well to hard pruning in early spring. Cut back stems to the lowest pair of strong buds, about 30cm above soil level.

clematis_composite

A final note

Many of us lose labels, forget names or inherit plants. Leave any unidentified clematis for a year, record when they flower and prune accordingly. It’s also worth noting that when you buy a clematis, you should plant it deeper than it is in the container – the stem bases should be covered with about 10cm of soil. The reason for this is that healthy shoots form from buds below soil level.

If you’re planting a young clematis which only has a couple of stems growing from the base, then you should prune it back hard in the first spring, whichever group it belongs to, to create a stronger, bushier plant. Cut stems back to just above the first set of strong healthy buds. Mulch your clematis well but keep the mulch back from the base of the stems.

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