Of the Ranunculaceae family, clematis are considered the most cultivated climbing plants, with the largest number of varieties in terms of shape, size and colour. These may take the shape of waterfalls, garlands, bells, lanterns or tulips. Vigorous, lively and spectacular, clematis beautify walls and arbours throughout the year. From March to November, large and small flowers brighten up the garden with a true explosion of colours.

There are about 200 species of clematis, of which the choice will primarily depend on the colour, vigour, and flowering dates. Deciduous or evergreen, of varying sizes, shapes and colours, some species can grow to heights reaching between 3 and 30 feet (1 to 10 meters) and will thrive in gardens to create beautiful settings.

The varieties of clematis

Depending on its intended use -  in flowerbeds, to colour a hedge, as ground cover or as a climbing plant – the available choices range from white to purple tending to black, to yellow, to variations of pink, purple and red. This diversity can sometimes complicate the choice, especially when that difference only concerns a shade of colour. However, some popular species have emerged as the undisputed stars. Among the most well-known species, one can cite the purple kinds such as ‘The President’ and ‘Lawsoniana’, the pink ones such as ‘Dr. Ruppel’ ‘Nelly Moser’ or’ Bee’s Jubilee ‘, and those in the red tones like ‘ Ville de Lyon’ and ‘Niobe’. Around the world, horticulturists have developed specimens that have unusual shapes and colours.

Depending on the season, different species will bloom. In spring, the small pink flowers of Anemone Clematis (Clematis montana) start emerging. The summer varieties are the most popular ones, as illustrated by the beautiful Clematis lanuginosa that brightens up our gardens with its large corrolas. In autumn, the Golden Clematis (Clematis tangutica) continues to illuminate gardens with its unique yellow colour, deploying its vigorous vines, before producing feathery fruit that create a beautiful visual effect. In winter, fern-leaved Clematis (Clematis cirrhosa) withstands the cold to complete its bloom and produce bell-shaped flowers. Some seem to play hide and seek, disappearing to better reappear, as is the case of Clematis ‘Hagley Hybrid’ which blooms a first time in May-June, then again in September.

Purchasing and planting clematis

The stems must be healthy, injury free, with lush green leaves. The preferred seedlings are branched at the base, have at least three stems, as well as strong and numerous roots.

They are to be planted in light, fertile and not too calcareous soil in spring to avoid the frosting period. Planting itself is carried out by digging holes large enough to accommodate shrubs, leaving a distance of 16 to 20 inches (40 to 50 cm) between seedlings in all directions in a mixture of peat and potting soil. When planting the root ball, tilt it towards its support. Then, bring the stems back along that support and attach them to help them grow. At the bottom, set up a layer of gravel, of which the thickness is 1.5 to 2 inches (4 to 5 cm) and which will act as a drainage layer. This system will allow the plant to thrive, as water represents a major element in its growth. If the clematis love the sun, it is nevertheless necessary to protect its base against direct rays that might burn it, either by using a tile or a layer of mulch.

These plants grow perfectly alongside a bush, against a wall, on a pergola, pole or arbour, or on a trellis being held up by a stake, fence or by leaning on other shrubs. Clematis combine very well with roses, honeysuckles and shrubs that have colourful foliage, as long as a harmony of colours is ensured.

Maintenance of clematis

The first key point to remember is to provide abundant watering to prevent the plants from wilting, especially in heavy soils where drainage may be more difficult. Otherwise, the main enemy of clematis is Phoma clematidina. Within hours, this fungus completely asphyxiates an apparently healthy plant that curls up until it dries completely. This disease mainly affects large-leaved species, while those with small flowers are spared. Vigilance is still the best medicine to uproot the plant on time and to identify the lesions and diseased parts needing to be removed, before replanting the stump in new potting soil.

On a daily basis, removing withered stems and flowers encourages the emergence of flowers and maintains the plant in good sanitary condition, except for species of which the fruits’ feathery bristles constitute a decorative asset. In summer, clematis need fertilizing, but one must avoid providing them with excessive nitrogen supplies.

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Published in Climbing plants by Alexander on 31 Aug 2011