Gymnocarpium robertianum

RHS Plant Profile
northern oak fern

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Other common names

limestone fern

Synonyms

Dryopteris robertiana, Polypodium calcareum

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

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
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