Clematis, Old-man’s beard
Clematis are among the most popular climbers for the garden. Here are the most important tips for planting, care and propagation.
The plant genus Clematis, also known as Waldrebe in German, comprises around 300 different species and belongs to the buttercup family (Ranunculaceae). The plants are predominantly native to the temperate climates of Europe and Asia as well as North America. There are almost 200 different wild species in China alone. In Central Europe, wild varieties of graybeard (Clematis vitalba) and the alpine clematis (Clematis alpina) are found. In addition, a whole range of wild species, their varieties and countless hybrid breeds have been cultivated and can be planted in several different ways in the garden.
Clematis are somewhat vigorous, woody climbers (lianas) or perennial, herbaceous shrubs. They tend to grow with the help of their bendable petioles, which is unique in the plant kingdom. Vigorous species such as Clematis montana can reach a height of 39.37 feet, most of them grow with shoots around 6.56 to 19.68 feet long. Their mostly alternately arranged leaves are patterned and the leaf shape is single or pinnate. The flowers are usually in paniculate inflorescences, sometimes also found individually in the leaf axils. The flowers of the wild species usually have four or five or even more petal-like sepals, which can be flat or upright and narrow to ovate in shape. There are no classic petals, but there are several free stamens, some of which are sterile and broad like a petal. The fertilized flowers give rise to single nut fruits, which come together in large numbers, on top of which sits the elongated stylus. A beautiful fall decoration, which can either be curved or feather-like.
Most of the clematis hybrids with large flowers, such as the well-known “Nelly Moser” variety are relatively slow-growing (photo): They rarely grow taller than 6.56 to 9.84 inches, form very thin shoots, and have the largest flowers in the entire range of clematis.
In their natural habitat, all clematis species grow in the somewhat shady edge of the forest. You therefore need a "shady location" in the garden, but enough sun shine further up. Locations on walls, fences or pergolas facing east or west are suitable options. As in the forest, the soil should be very humus-rich, permeable and always moist. Good drainage is important because the roots of all clematis are very sensitive to waterlogging.
Most experts recommend late summer as the optimal planting time for clematis. However, you can plant your clematis at any other time during the gardening season, as long as you water the plant sufficiently thereafter. While planting Clematis the most important thing to keep in mind is good soil preparation and right location. As already mentioned above, the ideal place is a climbing aid or a scaffolding that is protected from the sun during noon. Dig a large planting hole and enrich the soil with plenty of deciduous humus or humus-rich potting soil from the garden center. If the soil is very loamy and heavy, dig the hole at least 23.62 inches and fill in a drainage layer of gravel at the bottom. If competitive trees or shrubs grow in the area, you should enclose the root area of your clematis with lawn border stones.
For the so-called large-flowered clematis hybrids, it is generally recommended to plant them so deep that the stem base is at least a hand's breadth below the surface of the earth; as the clematis group is somewhat prone to wilting diseases. However, the fungal pathogens usually only destroy the above-ground part of the clematis and if the planting is sufficiently deep, it will usually thrive again from the shoot section hidden in the ground.
As a climbing aid, a trellis of lightweight longitudinal and transverse struts, on which the clematis can anchor itself with its leaf tendrils, is recommended. Inexpensive solutions are, for example, a reinforcement mat or a piece of wire mesh that is fixed to a wooden frame.
Caring for a clematis is not laborious: In addition to the necessary pruning measures (see below), the plant only needs a ground cover made of bark compost and a few taller shrubs in the root area that cover the base. Rodgersias, ferns or even taller varieties of hostas are suitable for this. Young plants can be fertilized using mature compost which is enriched by a handful of horn shavings. The large-flowered hybrids in particular grow much faster and bloom more profusely. Apart from that, it is only important to ensure a good water supply if there is persistent drought.
Clematis are pruned back to different degrees. They are divided into three cutting groups, depending on the flowering time and growth pattern:
In the first cutting group are the wild varieties that bloom from April to June such as the alpine clematis or the mountain clematis. They do not need regular cutting. If a rejuvenation cut is required after a few years so that the plants do not age fast, cut all the shoots back to the desired length immediately after flowering at the beginning of June. The plants then have time to form new shoots until the buds are formed in late summer.
Second cutting group includes all large-flowered clematis hybrids that bloom twice a year, once in May/June and once in August/September. In November/December all shoots are cut back to about 3.28 feet. In order to stimulate a second bloom, you should also cut off all the fruit clusters along with the pair of leaves underneath them, after the first bloom in mid-June.
In the species and varieties of the third group all shoots are cut in November/December to 7.87 to 19.68 inches above the ground. All shrub Clematis, Clematis viticella and their varieties as well as the popular hybrid “Jackmanii” come in this category.
The fast-growing wild species and their varieties can be used to green fences, grow on pergolas or scramble up trees. The large-flowered Clematis hybrids are mainly used for Trellises on house and garage walls, rose arches or for garden obelisks. They also make a pretty picture with climbing roses. Compact growing Clematis species and varieties that bloom for a long time, can grow well in a container on a trellis. The clematis shrubs fit into the flower bed and can be combined with other flowering shrubs and grasses. Some species are also suitable for use as ground cover.
In nature, the common clematis (Clematis vitalba) overruns shrubs, walls and climbs trees. It blooms from July to September with countless white mini-flowers that are mildly scented. These are often visited by bees and other insects. A beautiful variety with slightly larger flowers, derived from the wild species, is “Paul Farges”, sometimes also available commercially under the name “Summersnow”
The alpine clematis (Clematis alpina) is rarely found in the wild in shrubberies and mountain forests in the Alps. Its shoots are 6.56 to 13.12 feet long, the alternately arranged leaves are single to double pinnate. The flowers have four blue sepals and numerous stamens. They stand individually on long stalks in the leaf axils. It flowers from May to July. Numerous varieties with white, pink, purple and light to deep blue flowers are available. The deep red flowering “Ruby” variety, which thrives in almost any location, is considered particularly robust and abundant in flowers.
The large-flowered alpine clematis (Clematis macropetala) is native to East Asia and grows almost as fast as the alpine clematis. The large leaves are usually biternate. The bell-shaped flowers are up to 3.93 inches wide and blue-violet in color. They carry numerous white sterile stamens that spread out like petals. Here are also varieties with white or pink and purple-pink flowers such as “Rosy O’Grady”. The flowering period is April and May.
The Mountain Clematis (Clematis montana) is particularly vigorous and ideal for greening pergolas and tree tops. It has ternate leaves. The Mountain Clematis blooms vigorously in May or June with countless wide spread light pink flowers. There are also varieties with white, salmon or dark pink flowers, some of which have a pleasant smell.
The Mongolian Clematis (Clematis tangutica), also called Gold clematis, is also vigorous and can form shoots up to 19.68 feet long. It belongs to the species that bloom in summer and forms numerous small, yellow bell flowers from June to September. In addition, it is bejeweled with decorative, feathery inflorescences in fall. There are some varieties with different shades of yellow, such as the lemon-yellow flowering variety “Golden Harvest”.
Die Mongolische Waldrebe (Clematis tangutica), auch Gold-Waldrebe genannt, ist ebenfalls starkwüchsig und kann bis zu 6 Meter lange Triebe bilden. Sie gehört zu den im Sommer blühenden Arten und bildet von Juni bis September zahlreiche kleine, gelbe Glockenblüten. Dazu kommen im Herbst die dekorativen, fedrigen Blütenstände als Schmuck. Es gibt einige Züchtungen mit unterschiedlichen Gelbtönen wie die zitronengelb blühende Sorte ‘Golden Harvest’.
The Italian clematis (Clematis viticella) can climb up to 13.12 feet. Its double-pinnate leaves, which have soft hair underneath, are up to 4.72 inches long. The plants bear broad bell-shaped to cup-shaped flowers from June to August and sometimes even in September. The species itself blooms with blue bell-shaped flowers. A wide range to choose from — leaving almost no desire for flowers unfulfilled. Cultivars are now becoming more popular than the large-flowered hybrids, as they are more robust, grow vigorously and largely immune to clematis wilt.
Large-flowered clematis hybrids are varieties in which flower size and abundance are particularly important. Often, once they bloom, the leaves are no longer visible. Several cultivars not only come from Japan, but also from the Baltic States, Germany and Great Britain. The flower diameter is 3.14 to 9.84 inches, depending on the variety, with most around 5.51 inches. For most varieties, there are two flowering periods, the hybrids bloom from May to June in spring and from August to September in summer. Newer breeds often produce flowers from June to September. Classics of this group are “The President” with blue flowers, the pink and carmine-red striped “Nelly Moser” and the bright white “Madama Le Coultre”.
Clematis shrubs (Clematis integrifolia, Clematis heracleifolia etc.) dies back every year in winter and regrows from the base in spring. The robust plants, suitable for almost any location, do not form any climbing organs on the leaf stalk. Depending on the type and variety, they reach heights of 15.74 to 78.74 inches. Taller species should be provided with a shrub support or allowed to grow in a climbing obelisk.
Clematis varieties can be propagated in late spring by semi-mature cuttings. Since the cuttings are prone to putrefaction, the propagation box must be aired frequently. In professional horticulture, fungicides are typically used as a preventive measure against fungal diseases in the cuttings.
For hobby gardeners, it is easier to just propagate Clematis by offsets: You simply place a shoot on the ground and cover every second leaf node with moist humus soil after removing the leaves at those nodes. During the season it forms roots in these places and can then be cut into several pieces in autumn.
The Clematis deadhead is a dreaded fungal disease that can be caused by different pathogens. Whole shoots wither and the plant dies off quite suddenly. The large-flowered hybrid varieties are particularly affected. The disease often breaks out, especially in locations that are too warm.