Information

GENERAL INFORMATION

Clematis are from the Ranunculaceae family which also includes anemones, aquilegias, delphiniums, hellebores and buttercups. They can initially be separated into either the large-flowered cultivars or the small-flowered species and cultivars, the first group encompassing the Group 2s which flower on old wood, and many Group 3s which flower on new wood. The second group of small-flowered species and cultivars includes the Group 1 clematis of evergreens, alpinas, macropetalas and montanas, and more Group 3 clematis such as the viticellas, texensis, tanguticas and other later-flower species.

With so many different species and cultivars available it's no wonder the clematis is a very popular garden plant, with something to suit everyone.

CLEMATIS GROUPS

EVERGREEN GROUP - PRUNING GROUP 1

This group is made up of the Armandii, Cirrhosa and Forsteri groups, and are very popular with gardeners because of course they provide green foliage throughout the winter months. Most of the evergreens are from New Zealand although some originate in China, India and southern Europe, and although they are fairly hardy in temperate gardens they do still require shelter from wind and frost. Many of these evergreens make lovely conservatory or greenhouse plants and even the rampant Armandiis can be kept under control with a bit of pruning.

These evergreens flower on old wood and don’t require hard pruning. If you do wish to prune your evergreen clematis back this should be done after flowering, but you should avoid cutting back into old wood because the plant might not produce new shoots from there. If you prune your evergreen clematis at any other time of year you may sacrifice flowers the following year because the plant won’t have had time to produce and ripen the necessary flower shoots.

ATRAGENE GROUP - PRUNING GROUP 1

This group is made up of the Alpinas, Chiisanensis, Koreana and Macropetala groups, and are originally from Scandinavia, central Europe, Korea, Japan and North America. They are easy to grow as they require little maintenance, and do well in cold, exposed gardens, as well as coping with full sun or shade.

The Atragenes are deciduous and usually vigorous climbers. They flower on old wood grown the previous season, usually in late spring or early summer, and usually the flowers are nodding blooms. These clematis establish quickly and are usually free from disease, particularly clematis wilt.

These clematis don’t require pruning but if they do become overgrown you can remove unwanted stems immediately after flowering.

MONTANA GROUP - PRUNING GROUP 1

The Montanas are natives of the Indian Himalayas and China, and make excellent garden plants with their prolific blooms in early spring. They establish quickly, are vigorous, deciduous and are very useful at covering large areas such as small buildings and walls.

As mentioned before with Group 1 clematis they don’t require pruning but can be tidied after flowering, and whole stems can be cut out if necessary.

DOUBLE & SEMI-DOUBLE LARGE-FLOWERED CULTIVARS - PRUNING GROUP 2

A cultivar is a variety of plant that originated and persisted under cultivation, and has therefore arisen from the deliberate hybridization of different clematis species, or developed from a natural mutation. Some cultivars produce semi-double or double flowers in late spring/early summer and then single flowers in early autumn, while a few have double flowers for both flowering periods.

These clematis suit so many different situations such as specimen plants that can be trained onto various supports, or partnered with other plants such as smell trees, shrubs, and particularly roses, providing the pruning requirements are similar. Most of these cultivars require some sun but can cope with a bit of shade, but full sun can bleach the blooms quite dramatically. On the other hand, too much shade can cause the petals to take on a green colour. They are also sensitive in that cold weather in late spring can affect their performance, sometimes causing the plant not to produce early flowers.

These cultivars flower on old wood, or the ripened stems from earlier on in the year and therefore should be pruned only after the main flowering period, and propagation by layering or cuttings is recommended to assure the same quality of flowers.

SINGLE LARGE-FLOWERED CULTIVARS - PRUNING GROUPS 2 & 3

This is one of the most popular groups, and what people usually imagine when talking about clematis, picturing the large, flat flowers associated with these cultivars. They can be divided into two main groups based on the fact that they flower either in mid-spring to early summer, or later on from midsummer to late autumn, and therefore with some thought a gardener can achieve a very long flower display.

The early flowering large-flowered cultivars blossom on old wood from the previous season’s growth and some may flower later in the season on the current year’s shoots. They belong to pruning group 1 and shouldn’t be pruned hard, but can be tidied up after the main flowering period is over. And it should be noted that some of these cultivars are prone to a fungal disease known as clematis wilt.

The later flowering large-flowered cultivars are from pruning group 3 which means that they flower on new wood, or the current year’s growth, and should therefore be pruned during late winter or early spring. These too are sometimes susceptible to clematis wilt.

Some of the smaller varieties of large-flowered cultivars are excellent for growing in containers.

VITICELLA GROUP - PRUNING GROUP 3

This is one of my favourite groups of clematis because they are a group that has been around for a long time and are relatively easy to grow being relatively wilt-resistant and undemanding. They don’t have particularly large flowers but the displays are usually stunning with the blooms sometimes completely hiding the foliage of the plant.

Viticellas produce their flowers from the current seasons growth and are very versatile in that they can cope with sun or some shade, and can be grown on their own as a specimen plant, or with other plants, or even as ground cover.

TEXENSIS-VIORNA GROUP - PRUNING GROUP 3

These clematis originate from Texas and are very popular probably because of the beautiful scarlet tulip-shaped blooms they produce. They are difficult to propagate and seeds aren’t easy to find so sometimes they are difficult clematis to obtain, and it is more likely that you will have a texensis cultivar these days.

They flower from early summer to late autumn depending on the variety and are semi-herbaceous/herbaceous scramblers which also look wonderful as ground-cover. They should be treated like any other garden perennial and pruned back in early spring to stimulate new growth from the roots.

These clematis are particularly prone to mildew which can destroy the leaves and flowers, and can also suffer from clematis wilt.

TANGUTICA GROUP - PRUNING GROUP 3

These yellow clematis are a very popular choice and originate from China. They have bright yellow, bell-shaped blooms and have particularly attractive seedheads. There are quite a few cultivars of Tangutica, and these vary in size quite considerably. Most of these clematis flower in early summer through to autumn, but a few will flower in later summer. They are particularly hardy and are useful in that they don’t require a lot of sun. They belong to pruning group 3 so should be pruned back hard in late winter/early spring and it should be noted that they often self-seed!

HERBACEOUS & SUB-SHRUBBY SPECIES & CULTIVARS - PRUNING GROUP 3

Most people assume that all clematis are climbers but with this group the top growth of truly herbaceous clematis dies back each winter and produces new growth from the roots in spring. This group includes the Heracleifolias and Integrifolias which don’t cling and make very useful border plants. They don’t grow particularly tall like some clematis although some will require artificial supports if you want them to provide height in the garden. Treat them like other perennials by cutting back the growth to ground level in spring, and every two or three years the clumps can be divided.

OTHER SPECIES & CULTIVARS

There are more unusual and exotic clematis that are a lot less readily available in nurseries or garden centres, although specialist suppliers are more likely to stock them.