Gymnocarpium robertianum

RHS Plant Profile

northern oak fern

Other common names

limestone fern

Synonyms

Polypodium calcareum
Dryopteris robertiana

Ferns Herbaceous Perennial

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A low-growing, deciduous fern that forms a delicate green carpet between 10-40cm in height. Finely divided, soft fronds, up to 14cm long, emerge from a creeping underground network of rhizomes

Position

Full shade, Partial shade

Soil Types

Chalk, Clay, Loam

Size

Time to Maturity: 2–5 years

Growing Conditions

Chalk Clay Loam

Moisture: Moist but well–drained
pH: Alkaline 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: Woodsiaceae
Native to GB/Ireland: Yes
Foliage: Deciduous
Habit: Matforming, Tufted
Genus: Gymnocarpium are small deciduous ferns with a slender creeping rhizome, and much-divided, triangular to ovate fronds
Name Status: Correct
Plant Range: Temperate N Hemisphere

How to Grow

Cultivation

Grows well in most moist but free draining soil in shade or partial shade. See how to grow ferns for further advice

Propagation

Propagate by sowing spores as soon as ripe, or by division in spring

Suggested planting locations and garden types

Wildlife gardens

Pruning

No pruning required, but can remove and dead or damaged fronds as required

Pests

Generally pest-free

Diseases

Generally disease-free