Clematis 'M. Koster' (Vt)

RHS Plant Profile
clematis 'M. Koster'

Synonyms

Clematis 'Margot Koster'
Clematis viticella 'Margot Koster'

Climber Wall Shrub

A climber 2-4m high, with green leaves, and flowers, 7-14cm across, composed of four or six, often twisted, deep rose-pink to red-purple sepals, the tips and edges curving backwards, and pale yellow or yellow-green anthers on paler filaments, from late summer to early autumn; many clematis are visited by bees for pollen, and some also provide nectar

Position

Full sun, Partial shade

Soil Types

Chalk, Clay, Loam, Sand

Max Height

2.5-4 metres

Max Spread

1-1.5 metres

Size

Time to Maturity
2–5 years
Max Spread
1-1.5 metres
Max Height
2.5-4 metres

Growing Conditions

Chalk Clay Loam Sand
Moisture
Moist but well–drained
pH
Acid or Alkaline or Neutral

Position

Full sun Partial shade
Aspect
South–facing or East–facing or North–facing or West–facing
Exposure
Sheltered
Hardiness
H6

Colour & Scent

Season Stem Flower Foliage Fruit
Spring
Summer
Autumn
Winter

Botanical Details

Family
Ranunculaceae
Native to GB/Ireland
No
Foliage
Deciduous
Habit
Climbing
Potentially harmful
Skin irritant. Wear gloves and other protective equipment when handling. Pets (rabbits): Harmful if eaten. For further information and contact numbers regarding pets, see the HTA guide to potentially harmful plants
Genus
Clematis can be deciduous or evergreen shrubs or herbaceous perennials, mostly climbing by twining leaf-stalks, and often with showy flowers. Some have attractive fluffy seedheads in autumn
Name Status
Accepted
Horticultural Group
Viticella Group are deciduous climbing shrubs with usually pinnate leaves, and nodding, single to double, open-bell-shaped flowers of small to medium-size, produced on the current year's growth in summer and early autumn

How to Grow

Cultivation

Grow in full sun or partial shade in containers (at least 45cm deep and wide) or in the ground, in cool, moisture-retentive, well-drained soil, with the crown 5-8cm deep to encourage new shoots to grow from below ground level; keep the base of the plant and the roots cool and shaded by other plants or a layer of pebbles or flat stones; for more advice, see clematis cultivation

Propagation

Propagate by internodal leaf-bud semi-ripe cuttings taken from spring to late summer, or by layering from late winter to spring

Suggested planting locations and garden types

  • City and courtyard gardens
  • Cottage and informal garden
  • Patio and container plants
  • Flower borders and beds
  • Wall side borders
  • Hedging and screens

Pests

May be susceptible to aphids, snails and caterpillars; petals may be eaten by earwigs

Diseases

May be susceptible to honey fungus (rarely), clematis wilt and clematis slime flux