Clematis are climbing plants that have a profusion of showy flowers in a variety of colours. Clematis are easy to grow but in order to obtain the optimal floral display a small amount of maintenance, mainly pruning, is required. The time to prune is not universal for all clematis and the following provides some guidelines.
Clematis are divided into three groups as follows:
Group 1, early flowering clematis
Group 1 includes Winter flowering clematis that bloom in Winter and Spring on the previous year’s growth. Clematis alpina, clematis macropetala, clematis napaulensis, clematis montana and their cultivars are considered to be group 1 clematis. Begin pruning clematis from group 1 immediately after flowering by removing any damaged or dead stems and reducing growth to the required size.
Group 2, large-flowered clematis
The large-flowered cultivars in group 2 bear flowers in late Spring and Summer on new shoots that originate from the previous year’s stems. Some cultivars will also produce a second flowering at the tips of the current year’s growth in late Summer and Autumn. Prune clematis from group 2 in Spring before they start growing by removing any damaged, dead or weak stems and cutting back to a pair of healthy buds; please note, heavy pruning at this stage may reduce the number of early flowers and should normally be avoided. In early Summer, when flowering has diminished, prune back, to encourage new growth, flowered stems to a set of strong healthy buds or a side shoot just below the faded blooms. Summer is also the time to prune back overgrown plants in order to to reduce their size; very overgrown plants should be reduced in size by repeating this exercise over a number of years rather than cutting back hard in one go.
Group 3, late flowering clematis
Group 3 contains the late flowering species and their cultivars that bloom from summer to late autumn on the current years stems. Clematis in group 3 are considered the easiest to prune. Prune group 3 clematis in spring before they start growing. To prune simply cut back to a pair of strong buds about 20cm above ground level, removing all of the previous year’s growth.