Hylomecon japonica

RHS Plant Profile
Japanese woodland poppy

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Japanese woodland poppy John Fielding
Japanese woodland poppy visionspictures.com
Japanese woodland poppy visionspictures.com

Synonyms

Chelidonium japonicum
Hylomecon vernalis

Herbaceous Perennial
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A clump-forming, spreading perennial to 30cm tall, with pale green mostly basal leaves composed of leaflets and bearing poppy-like deep-yellow flowers 5cm across, from late spring to summer

Position

Full shade, Partial shade

Soil Types

Clay, Loam

Max Height

0.1-0.5 metres

Max Spread

0.1-0.5 metres

Size

Time to Maturity
2–5 years
Max Spread
0.1-0.5 metres
Max Height
0.1-0.5 metres

Growing Conditions

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

Position

Full shade Partial shade
Aspect
East–facing or North–facing
Exposure
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)
H5

Colour & Scent

Season Stem Flower Foliage Fruit
Spring
Summer
Autumn
Winter

Botanical Details

Family
Papaveraceae
Native to GB/Ireland
No
Foliage
Deciduous
Habit
Clump forming
Genus
Name Status
Correct
Plant Range
Far East

How to Grow

Cultivation

Grow in moist but well-drained neutral to acid soil rich in organic matter, in a position in partial or deep shade. Ideal as a wild or woodland garden plant

Propagation

Propagate by seed as soon as ripe or in autumn or propagate by division in spring

Suggested planting locations and garden types

  • City and courtyard gardens
  • Cottage and informal garden
  • Wildlife gardens
  • Flower borders and beds

Pruning

Tidy after flowering is finished in late summer or autumn

Pests

May be susceptible to slugs and snails, especially in spring

Diseases

Generally disease-free