Osmunda japonica

RHS Plant Profile

Asian royal fern

Ferns

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A decidious fern with an erect, ascending, or shortly creeping rhizome. It produces a cluster of green fronds, each up to 150cm tall and 50cm wide. The spore-bearing fertile fronds are more upright and of a bronze hue.

Position

Partial shade

Soil Types

Loam, Clay

Max Height

1-1.5 metres

Max Spread

0.5-1 metres

Size

Time to Maturity: 5–10 years
Max Spread: 0.5-1 metres
Max Height: 1-1.5 metres

Growing Conditions

Loam Clay

Moisture: Poorly–drained or Moist but well–drained
pH: Neutral or Acid

Position

Partial shade

Aspect: West–facing or 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): H6

Colour & Scent

Season	Stem	Flower	Foliage	Fruit
Spring
Summer
Autumn
Winter

Botanical Details

Family: Osmundaceae
Native to GB/Ireland: No
Foliage: Deciduous
Habit: Clump forming
Genus: Osmunda are medium-sized to large deciduous ferns, usually from wet places, with erect or arching, pinnate or bipinnate fronds, bearing spores either on modified pinnae or on separate, smaller fronds
Name Status: Correct
Plant Range: Pakistan to Japan

How to Grow

Cultivation

Succeeds in most moist soils, preferring acid conditions and requires a constant supply of water, doing well by ponds, lakes or streams. Plants will tolerate sun so long as there is no shortage of moisture in the soil.

Propagation

Propagate by division or spores

Suggested planting locations and garden types

Cottage and informal garden
Low Maintenance

Pruning

Remove any dying fronds if required.

Pests

Generally pest-free

Diseases

Generally disease-free