Pruning
A guide to pruning clematis
Introduction
When and how to prune is probably the most frequently asked question about clematis. It can be broadly answered by the phrase ‘if it flowers before June, don’t prune’. Clematis that flower just after that can be pruned a little and those that flower later can be pruned a lot.
Most suppliers place clematis into one of three groups for pruning purposes. This page briefly explains the differences between these groups.
If you know the name of a clematis but are unsure which group it falls into, search online for ‘Clematis on the web’, where you will find a comprehensive description of each clematis including its pruning requirements.
Group 1: Clematis that flower between March and the end of May
Clematis that flower early in the year will have developed their flower buds before the previous winter and should not be pruned before they flower. Many of these plants are well behaved and don’t become too big, but if they have outgrown their allotted space, and are causing you problems, prune them back immediately after flowering. Some clematis from the montana family may become quite large when established and will need cutting back after flowering.
Family groups include: alpina, macropetala, montana, armandii, cirrhosa and New Zealand cultivars.
Group 2: Clematis that begin flowering between the end of May and the end of June
These are clematis which are usually referred to as early large-flowered hybrids. They produce their main flush of flowers in June on short growths from the stems made in the previous year. Some also produce a second (smaller) flush of flowers in August/September. For this group pruning is restricted to tidying up by removing old flower stems, seed heads and broken, dead and weak stems in February or March.
Start at the top of the plant and work downwards along each stem until you meet a pair of plump, healthy buds, and prune just above, removing any top growth. If you prune further down the plant you will be cutting off stems that will produce the early flowers. After enjoying the early flowers, you may prune back some of the flowered stems to encourage new growth from lower down the plant. It may also be beneficial to remove any seed heads that are forming.
There are many clematis varieties that belong to this family group, some of which are old favourites such as 'Nelly Moser', 'Will Goodwin', ‘Alice Fisk’, ‘Carnaby’, ‘Guernsey Cream’ and ‘The President’.
If the plant has outgrown its position or has become unsightly, with a large tangle at the top, prune the whole plant by at least half its height after the first flush of flowers.
Group 3: Clematis that flower from June onwards
This group includes the late large-flowered hybrids and clematis (and their various family groups) that flower from the end of June onwards on the current year’s growth. Pruning is normally undertaken in February, March or even April, depending on how northerly your garden is.
Start at the bottom of the plant and work upwards to the second pair of live buds and prune the stem just above them, and remove all the top growth above the cut. There may well be live growth above this point but be brave, cut it off! Harsh as this treatment sounds, your plant will be encouraged to make strong new growths to produce an abundance of flowers within a matter of months.
Allow this new growth to grow 30cm then pinch out the growing tips just above the top leaf joint. This will double the number of stems produced and, therefore, increase the number of flowers.
Winter-flowering clematis
These are usually included in Pruning Group 1, which means that they don’t require pruning. However, some species such as napaulensis can look rather brown and unsightly during the summer months and may benefit from tidying up once they have produced their new green growth. Do not, however, prune any of the new green stems as these will produce the winter flowers.
General
The most natural way of growing clematis is to allow them to grow through other established shrubs and trees and the late-flowering clematis (group 3) are possibly the best for this method of display. However, during the winter clematis top growth can look rather dull and unsightly. If this is the case prune the top half of the stems to reduce the mass and then finish off the pruning in the usual way in February/ March. Do not be tempted to hard prune too early as the plant will be excited into growth and the new shoots will fall prey to early frost and hard weather.
After pruning, plants will benefit from a mulch using garden compost mixed with a handful of bonemeal or blood, fish and bone mix.
Take care with thick, old stems of established plants because they may not easily produce new growth. To rejuvenate old or spindly clematis prune one half one year and the other half the following year.