Clematis 'Semu' (LL)

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clematis 'Semu'

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clematis 'Semu' RHS
clematis 'Semu' RHS

Synonyms

Clematis 'Caddick's Cascade', Clematis [Caddick's Cascade]

Climber Wall Shrub
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A deciduous climber, 2-3m tall, with dark green foliage and medium-sized flowers, 8-14cm in diameter, from midsummer to autumn. The flowers are a light purple to lilac blue colour with violet veining, a paler central bar and dark red to brownish anthers

Position

Full sun, Partial shade

Soil Types

Chalk, Clay, Loam, Sand

Max Height

2.5-4 metres

Max Spread

1.5-2.5 metres

Size

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

Growing Conditions

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

Position

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

Hardiness Ratings

All ratings refer to the UK growing conditions unless otherwise stated. Minimum temperature ranges (in degrees C) are shown in brackets

  • H1A: under glass all year (>15C)
  • H1B: can be grown outside in the summer (10 - 15)
  • H1C: can be grown outside in the summer (5 - 10)
  • H2: tolerant of low temperatures, but not surviving being frozen (1 to 5)
  • H3: hardy in coastal and relatively mild parts of the UK (-5 to 1)
  • H4: hardy through most of the UK (-10 to -5)
  • H5: hardy in most places throughout the UK even in severe winters (-15 to -10)
  • H6: hardy in all of UK and northern Europe (-20 to -15)
  • H7: hardy in the severest European continental climates (< -20)
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

Horticultural Classification Codes

Horticultural Classification Codes are often given to genera which have a large number of species or cultivars. They are used to categorise cultivated plants based on specific, shared characteristics such as shape, colour, size or flowering time, and can be displayed as letters or numbers

For example:
Dahlia ‘Sunset Kate (Sin) = Single flower
Rosa ‘Marigold’ (HT) = Hybrid Tea

Late Large-flowered clematis are deciduous climbers with large, star-shaped flowers to 15cm wide, opening on the current year's growth in summer and autumn

How to Grow

Cultivation

Plant in a moisture-retentive, well-drained soil, with the roots and base of the plant kept cool and shaded by other plants or a layer of pebbles at the base. Plant with the crown 5-8cm deep to encourage new shoots to grow from below ground level. See clematis cultivation

Propagation

Propagate by layering or semi-hardwood cuttings

Suggested planting locations and garden types

  • Cottage and informal garden
  • City and courtyard gardens
  • Patio and container plants
  • Wall side borders

Pruning

Pruning (Clematis) Group 3. Flowers on current season's growth

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