Of all the climbers available to the British gardener, Clematis surely offer the longest flowering period, with many species and hybrids that bloom during virtually every month of the year. Here at Chartwell we have recently finished pruning many of our various Clematis plants, but that in itself doesn’t tell the whole story. Clematis are divided into three main groups based upon their flowering time and habit. Each of these groups are also dealt with differently when it comes to pruning them too. It is very important to check which group your Clematis belongs to before carrying out any pruning or renovation, because if done incorrectly, flowering wood may be removed resulting in no blooms for a year at least.
Group 1 is made up of the early flowering species and their cultivars and includes the C. montana plants such as the one shown above, climbing up the side of the mansion at Chartwell. This group of Clematis flower directly on the previous season’s ripened stems. These plants tend to be very vigorous and generally require little, if any, regular pruning, especially if they are cut back hard when first planted. We prune our ‘Grandiflora’ every year however, just to keep it in check and stop it getting out of hand. The time to prune Group 1 species is any time from immediately after flowering, right up until Spring and this year Matt and myself tackled it back in January. For very vigorous Clematis like this one, the task can even be carried out by shearing them all over to keep them tidy. As this particular climber is beginning to become too bushy and congested on the side of the house, we are considering pruning it hard later in the year to renovate it completely. We would do this straight after flowering to a low set of buds on the old wood and it will still respond and recover well.
Group 2Clematis consist of the early, large-flowered cultivars which bloom on short, current season stems. These stems arise from the previous season’s ripe wood. Clematis ‘The President’, as shown above, can be found in one of the borders surrounding Lady Churchill’s Rose Garden at Chartwell. The pruning of this group is generally done in late Winter or very early Spring, often around February time as Ann did with ‘The President’ this year. The aim is to retain a framework of old wood while stimulating new shoots to provide as many flowers as possible for the coming flowering season (May to June). Dead or weak stems are removed while the retained stems are pruned just above the lowest or penultimate set of buds. Very heavy pruning should be avoided as flower buds will be lost. A second flush of flowers can often be encouraged by carrying out a second prune immediately after flowering to a large bud or strong side shoot directly beneath the initial bloom.
Group 3 includes the late flowering species and cultivars such as ‘Perle D’Azur’ which can be seen in the Soloman’s Seal Border above. Flowers produced by this group are on stems of the current season’s growth. Pruning is carried out in late Winter or early Spring before any serious new growth starts. This year Rhiannon pruned this one in February. All of the previous year’s shoots are reduced down to a strong pair of leaf buds just above the base of the previous season’s growth, generally 15 to 30cm above soil level. New growth in the coming months will be tied in to the wires on the wall as needed, spacing them evenly.
Herbaceous Clematis, like the one pictured above in the Herbaceous Border in our Kitchen Garden, are also included within Group 3. I pruned this one to the same principals as part of the herbaceous cut back as discussed in a previous post. Make sure you come back to Chartwell regularly throughout the coming season to see all of our Clematis in full flower as they benefit from their various pruning schedules…