Carex oshimensis

RHS Plant Profile
Japanese sedge

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Synonyms

Carex morrowii misapplied

Grass Like
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Durable, densely tufted, clump-forming, evergreen perennial sedge, 30-40cm tall, with fine-textured, glossy green foliage. Carries inconspicuous brown flower spikes on stems to 15cm long, within the foliage, in mid and late spring

Position

Full sun, Partial shade

Soil Types

Chalk, Clay, Loam, Sand

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

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

Position

Full sun Partial shade
Aspect
South–facing or West–facing or East–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)
H7

Colour & Scent

Season Stem Flower Foliage Fruit
Spring
Summer
Autumn
Winter

Botanical Details

Family
Cyperaceae
Native to GB/Ireland
No
Foliage
Evergreen
Habit
Clump forming, Tufted
Genus
Carex can be deciduous or evergreen, rhizomatous or tufted perennials, with triangular stems bearing linear or strap-shaped leaves and short or long spikes of tiny green or brown flowers
Name Status
Correct
Plant Range
Japan

How to Grow

Cultivation

Grow in fertile moist but well-drained soil in full sun or part shade. See ornamental grasses cultivation

Propagation

Propagate by seed in early spring or by division in mid spring to early summer

Suggested planting locations and garden types

  • City and courtyard gardens
  • Coastal
  • Cottage and informal garden
  • Gravel garden
  • Patio and container plants
  • Low Maintenance
  • Flower borders and beds
  • Garden edging

Pruning

Cut out any dead leaves on evergreen species in summer

Pests

May be susceptible to aphids

Diseases

Generally disease-free