Climbing Clematis

There are a great many species and hybrids of clematis. All climb readily by twisting their leaf stalks round the nearest available support. The hybrids, which produce large, exotic-looking blooms, are easier to grow than they look. Each variety keeps to a timetable for blooming, so by planning you can have a succession of clematis flowers right through the summer. All the clematis described below are deciduous.

  • C. montana is vigorous, hardy, and easy to grow. It climbs as high as 9m (30 ft), producing small white flowers, slightly scented, in May and June. The main problem is to keep it under control. C. alpina, growing to 2.4m (8 ft), is not a strong grower, but produces delightful, bell-shaped blue flowers in April and May.
  • C. jouiniana grows to 3m (loft), but needs tying to supports to help it climb. Produces lilac flowers from August to October.
  • C. jacicmanii, bred by Jackman’s of Woking in Victoria times, has justifiably retained its popularity to this day. Easy to grow and vigorous, growing to 6 m (20 ft), it produces masses of large purple flowers, with a darker stripe, from July onward. Similar in appearance, but not in the same grouping, are the large-flowered hybrids such as ‘Nellie Moser’ (pink and mauve flowers in May and September), ‘The President’ (purple, June and September), and ‘Ville de Climbing ClematisLyon’ (carmine red, June and September). All grow to about 3m (10 ft) tall. Clematis give a mass of growth starting from a very small base, so a lot of plants can be put into quite a small plot.

General care: Clematis are tolerant of a lot of different growing conditions, but prefer their roots in the shade in moisture-retaining soil with some chalk. Their top growth likes the sun but some flowers, such as ‘Nellie Moser’, bleach in sunlight and should be planted on a north wall. Heavy day soil should be lightened with peat or leaf mould. Clematis do not like their roots disturbed, so always use container-grown plants, putting them in at any time during the winter.

Correct pruning is essential if clematis are to give of their best in flowers. C. montani2 blooms on the previous year’s growth so pruning, if done at all, should be carried out just after flowering. C. alpina seldom needs pruning, C. jouiniana may need some top growth cut back after a few years to encourage basal shoots. C. jacicmanii flowers on the current year’s growth, and should be cut right back in February to encourage young shoots. ‘Ville de Lyon’ needs the same treatment, but ‘Nellie Moser’ and ‘The President’ need only light pruning to tidy the plant.

Propagation: Clematis can be raised from seed, but the offspring are often not as good as the parents. Cuttings can be taken in July and rooted in a 50-50 mixture of peat and sand, but the most reliable way of propagating on a small scale is to layer shoots in the spring, and separate them from the parent a year later. Pests and diseases: Aphids attack young shoots. Spray with malathion or menazon. Clematis wilt, a fungal disease, causes shoots – often a whole young plant – to wilt and die rapidly but fresh shoots usually appear from the base the next year. Use a copper fungicide on the new shoots in the spring.

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