Parnassia palustris

RHS Plant Profile

grass of Parnassus

Mike L. Grant 2001

Other common names

brial y gors

Synonyms

Parnassia palustris var. tenuis

Bogs Herbaceous Perennial

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A rosette-forming perennial to 20cm in height, with heart-shaped basal leaves and erect stems bearing star-shaped white flowers 2.5cm across, with greenish veins, in late spring and early summer

Position

Full sun

Soil Types

Clay, Loam

Max Height

0.1-0.5 metres

Max Spread

0-0.1 metre

Size

Time to Maturity: 2–5 years
Max Spread: 0-0.1 metre
Max Height: 0.1-0.5 metres

Growing Conditions

Clay Loam

Moisture: Poorly–drained
pH: Acid or Alkaline or Neutral

Position

Full sun

Aspect: West–facing or South–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: Celastraceae
Native to GB/Ireland: Yes
Foliage: Deciduous
Habit: Clump forming
Genus: Parnassia are herbaceous perennials with basal rosettes of ovate or heart-shaped leaves, with solitary bowl-shaped white or pale yellow flowers on upright leafy stems
Name Status: Correct
Plant Range: Eurasia

How to Grow

Cultivation

Grow in deep, fertile, wet but not stagnant soil in full sun

Propagation

Propagate by seed, sown in containers in autumn, or by division in spring

Suggested planting locations and garden types

Wildflower meadow
Rock garden

Pruning

Cut back after flowering

Pests

May be susceptible to slugs and snails

Diseases

Generally disease-free