Regular pruning of clematis encourages strong growth and flowering and keeps the growth in check. If left unpruned, clematis can turn into a mass of tangled stems with bare base and flowers well above eye level.
Timing The main pruning season is late winter to early spring, but some can also be pruned in early summer after their first flush of flowers
Difficulty Easy to moderate
Although there are numerous clematis species, hybrids and cultivars, for pruning purposes they are split into three distinct pruning groups based on the time of flowering and the age of the flowering wood.
When to prune clematis
Prune at the following times;
- Pruning Group 1: Prune mid- to late spring, after flowering and once the risk of frost has passed
- Pruning Group 2: Prune in February and after the first flush of flowers in early summer
- Pruning Group 3: Prune in February
Established clematis fit into three main pruning groups consistent with flowering times.
Pruning Group 1
This group comprises the early-blooming clematis that flower on shoots produced the previous season. They require no regular pruning except for the removal of faded flowers. In subsequent years some training and perhaps thinning may be necessary. If renovation is required, plants can be cut back to 15cm (6in) from the base, after flowering. This operation will affect flowering and should not be carried out again within three years.
Pruning Group 2
This group comprises the large-flowered cultivars that flower in May to June on short shoots developing from the previous year's growth. Some flower again in late summer on new growth. They require only to have the flowers cut off, back to a large growth bud immediately below the flower as soon as flowering is over. They can, if preferred, be left unpruned other than for the removal of dead shoot ends in spring.
Pruning Group 3
This group comprises clematis that flower from mid- to late summer on the terminal 60cm (2ft) or so of the current year’s growth. If this type is left unpruned growth will continue from where it ended the previous season, resulting in a tangled mass of growth, flowering often well above eye level and stems bare at the base. These late-flowering clematis are best pruned back hard in February each year to the lowest pair of buds.
Combining Pruning Groups 2 or 3
Some mid- to late summer flowering clematis may be pruned by combining method 2 and 3, to retain a basic framework while cutting other stems to the base. This extends the flowering season.
Prune herbaceous clematis such as C. heracleifolia, C. integrifolia and C. recta to near ground level in late autumn or early spring.
Unsure of which pruning group
If you are unsure or forget which group your clematis fall into, observe the flowering time on your plant and use the following simple guide;
- Flowering before early summer (June), do not prune
- Flowering from late June onwards, prune in late winter (February)
Powdery mildew is very common on clematis and clematis wilt is also sometimes seend. Pruned stems may fail to reshoot and ooze a sticky substance – this is known as slime flux.Occasionally clematis produce green petals or flowers.
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