Topic: Clematis, forest vine
The plant genus Clematis, also called forest vine, comprises about 300 different species and belongs to the family of the buttercup family (Ranunculaceae). The plants are mainly native to the temperate climates of Europe and Asia as well as North America. In China alone there are almost 200 different game species. In Central Europe there are wild occurrences of the common grapevine (Clematis vitalba) and the alpine grapevine (Clematis alpina). In addition, a whole range of wild species, their varieties and countless hybrid breeds are in cultivation and can be used in the garden in many ways.
Appearance and growth
Clematis are more or less fast-growing, woody climbing plants (lianas) or perennial, herbaceous shrubs. They climb with the help of their curvilinear petioles, which is a peculiarity of the plant kingdom. Strong growing species like Clematis montana can reach a growth height of 12 meters, most grow with shoots about 2 to 6 meters long. The leaves, which are mostly opposite to each other, are stalked and the leaf shape is simple or pinnate. The flowers usually stand in panicled inflorescences, rarely also individually in the leaf axils. Wild flowers usually have four or five or more petal-like sepals, which can be flat or upright and narrow to ovate in shape. There are no classical petals, but many free stamens which are partly sterile and widened like petals. The fertilized flowers produce lonesome nut fruits, which stand together to many and on which the elongated styli still sit, which can be curved and feathery and are a beautiful autumn decoration.
Most large-flowered Clematis hybrids, such as the well-known variety ‘Nelly Moser’ (photo), are relatively slow-growing: they rarely grow taller than two to three metres, form very thin shoots and carry the largest flowers in the entire Clematis range.
Location and soil
All Clematis species have their natural habitat at the more or less shady edge of the forest. You therefore need a “shady foot” in the garden as well, but you should get enough sun further up. Locations on walls, fences or pergolas facing east or west have proven successful. As in the forest, the soil should be very rich in humus, permeable and constantly moist. Good drainage is important as the roots of all clematis are very sensitive to waterlogging.
Most experts recommend late summer as the optimum planting time for clematis. However, you can also plant your clematis at any other time during the gardening season, as long as you water the plant sufficiently afterwards. When planting clematis, good soil preparation and the right choice of location are of particular importance. As mentioned above, the optimal place is a climbing or climbing aid that is sheltered from the sun during lunchtime. Dig a large planting hole and improve the soil with plenty of deciduous humus or humus-rich soil from the garden centre. If the soil is very loamy and heavy, dig a hole at least 60 centimetres deep and fill it with a gravel drainage layer. If you grow trees or shrubs in the surrounding area, you should surround the root area of your clematis with lawn curbs. For the so-called large-flowered clematis hybrids, it is generally recommended to place the plants so deep that the stem base is at least a hand’s width below the surface of the earth. The reason for this is that this clematis group is somewhat susceptible to withering diseases. As a rule, however, the fungal pathogens only destroy the above-ground part of the clematis, so that if the clematis is planted sufficiently deep, it will usually drift through again from the shoot section concealed in the soil. Low-cost solutions are, for example, a construction steel mesh or a piece of wire mesh fixed to a wooden frame.
The care of a Clematis is not very complex: In addition to the necessary pruning (see below), the plant only needs a soil cover of bark compost and a few higher shrubs in the root area that shade the foot. Rodgersias, ferns or even higher Funkien varieties are suitable for this. Young plants can be fertilized in spring with some ripe compost, which you enrich with a handful of horn flour. Especially the large-flowered hybrids grow much faster and flower more abundantly. Otherwise, it is only necessary to ensure a good water supply if the drought persists.
Clematis are cut back to different degrees. Depending on the flowering period and growth form, they are therefore divided into three cut groups: Cut group 1 includes wild species that flower from April to June, such as the alpine forest grapevine or the mountain forest grapevine and their varieties. They do not need to be cut regularly. If a rejuvenation pruning is necessary after years so that the plants do not age, all shoots are cut back to the desired length immediately after flowering at the beginning of June. Cut group 2 comprises all large-flowered Clematis hybrids that flower twice a year, once in May/June and once in August/September. In November/December all shoots are cut back to about one meter. In order to stimulate a second flowering, it is also advisable to cut off all the fruit after the first flowering in mid-June with the pair of leaves underneath. For the species and varieties in cut group 3, all the shoots are cut off to 20 to 50 centimetres above the ground in November/December. This includes all perennial Clematis, Clematis viticella and their varieties as well as the well-known hybrid ‘Jackmanii’.
Use in the garden
The fast-growing wild species and their varieties can grow on fences, pergolas or trees. The large-flowered Clematis hybrids are mainly used for trellises on house and garage walls, rose arches or obelisks. They are also often combined with climbing roses. Long flowering, compact growing species and varieties of clematis can grow well in a tub on a trellis. The perennial clematis fit into the bed where they can be combined with other flowering perennials and grasses. Some species are also suitable for use as ground cover.
Important species and garden shapes
The common vine (Clematis vitalba) overgrows bushes, walls and climbs into trees in nature. It blooms from July to September with countless white mini blossoms that have a faint fragrance. These are often visited by bees and other insects. A beautiful variety derived from the wild species with slightly larger flowers is ‘Paul Farges’, sometimes also known as ‘Summersnow’.
The alpine forest grapevine (Clematis alpina) is rarely found in the bushes and mountain forests of the Alps. Its shoots are 2 to 4 metres long, the opposite leaves are single to double pinnate. The flowers bear four blue sepals and numerous stamens. They stand individually on long stems in the leaf axils. Flowering time is from May to July. There are a number of varieties whose flowers can be white, pink, purple and light to deep blue. The deep-red flowering variety ‘Ruby’, which can cope with almost any location, is considered to be particularly robust and flower-rich. The large-flowered alpine forest grapevine (Clematis macropetala) is originally native to East Asia and grows about as strongly as the alpine forest grapevine. The large leaves are usually double-three-numbered. The bell-shaped flowers are up to 10 centimetres wide and blue-violet in colour. They carry numerous white sterile stamens, which are widened like petals. There are also varieties with white or pink and purple-pink flowers such as ‘Rosy O’Grady’. Flowering time is April and May.
The mountain vine (Clematis montana) is particularly vigorous and ideal for planting pergolas and treetops. The foliage is threefold. The Berg-Waldrebe flowers richly in May or June with countless widely spread light pink flowers. In addition, there are varieties with white, salmon or dark pink flowers, some of which have a pleasant fragrance. The Mongolian clematis tangutica, also known as the golden vine, is also vigorous and can form shoots up to 6 metres long. It belongs to the summer flowering species and forms numerous small yellow bellflowers from June to September. In autumn the decorative, feathery inflorescences are added as decoration. There are some varieties with different yellow tones like the lemon yellow flowering variety ‘Golden Harvest’.
The Italian wood vine (Clematis viticella) can climb up to 4 metres high. Its double-feathered leaves, softly haired underneath, grow up to 12 centimetres long. From June to August and sometimes even in September, the plants have broad bell-shaped to cupped flowers. The species itself blooms with blue flower bells. There is a particularly rich selection of varieties, which actually leaves almost nothing to be desired. The cultivars are planted more and more frequently instead of the large-flowered hybrids because they are more robust, more vigorous and largely immune to clematis wilt.
Large-flowered Clematis hybrids are cultivars in which flower size and abundance are particularly important. When these bloom, one often sees no more foliage. Many breeds come from Japan, but also from the Baltic States, the United States and Great Britain. Depending on the variety, the flower diameter is 8 to 25 centimetres, with most around 14 centimetres. Most varieties flower in two parts, in spring the hybrids flower from May to June and in summer from August to September. Newer varieties often bear flowers from June to September. Classics of this group are the blue flowering ‘The President’, the pink and carmine striped ‘Nelly Moser’ and the bright white ‘Madama Le Coultre’. Clematis (Clematis integrifolia, Clematis heracleifolia, etc.) grow their shoots every year in winter and sprout again at the base in spring. The robust plants, which are suitable for almost any location, do not form any climbing organs on the petioles. Depending on the species and variety, they can reach heights of 40 to 200 centimetres. Higher species should be provided with a perennial support or grown in a Rank obelisk.
Clematis varieties can be propagated in late spring by half ripe cuttings. Since the cuttings are very susceptible to rot, however, the seed tray must be aired frequently. In professional horticulture, fungicides are usually used as a preventive measure to prevent fungal diseases in the cuttings. For hobby gardeners, it is much easier to propagate clematis by means of cuttings: you simply place a shoot on the ground and cover it with moist humus soil at every second leaf node after removing the leaves. In the course of the season it forms roots in these places and can then be divided into several pieces in autumn.
Diseases and pests
Clematis wilt is a dreaded fungal disease that can be caused by different pathogens. This leads to a relatively sudden withering of whole shoots and the death of the plant. Especially the large-flowered hybrid varieties are affected. The outbreak of the disease often occurs especially in locations that are too warm.
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I am Don Burke, one of the authors at My Garden Guide. I am a horticulturist that cultivates, grows, and cares for plants, ranging from shrubs and fruits to flowers. I do it in my own garden and in my nursery. I show you how to take care of your garden and how to perform garden landscaping in an easy way, step by step.I am originally from Sydney and I wrote in local magazines. Later on, I have decided, more than two decades ago, to create my own blog. My area of specialization is related to orchid care, succulent care, and the study of the substrate and the soil. Therefore, you will see many articles dedicated to these disciplines. I also provide advice about how to improve the landscape design of your garden.