Caltha polypetala Hochst. ex Lorent

RHS Plant Profile
giant marsh marigold

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giant marsh marigold RHS
giant marsh marigold RHS

Synonyms

Caltha palustris subsp. polypetala

Aquatic Bogs Herbaceous Perennial
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A vigorous marginal aquatic perennial, up to 60cm high and 90cm wide, spreading by rooting stems across ground or across water. It has rounded green leaves, the basal leaves up to 10cm across, the stem leaves fewer and smaller, and shining, bright golden yellow flowers, up to 5cm across, from early spring to summer

Position

Full sun

Soil Types

Chalk, Clay, Loam, Sand

Max Height

0.5-1 metres

Max Spread

0.5-1 metres

Size

Time to Maturity
2–5 years
Max Spread
0.5-1 metres
Max Height
0.5-1 metres

Growing Conditions

Chalk Clay Loam Sand
Moisture
Poorly–drained
pH
Acid or Alkaline or Neutral

Position

Full sun
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
Ranunculaceae
Native to GB/Ireland
No
Foliage
Deciduous
Habit
Clump forming
Genus
Caltha are rhizomatous herbaceous perennials with simple, usually heart-shaped leaves and cup-shaped yellow or white flowers in early spring
Name Status
Correct
Plant Range
Temp N Hemisphere

How to Grow

Cultivation

Plant from spring to autumn in full sun, in deep, rich organic soil, at the water's edge or in shallow water up to 15cm deep; mulch annually to conserve moisture. See pond plants and bog gardens for further advice

Propagation

Propagate by seed, sown fresh in late summer in a cold frame, making sure that the compost does not dry out, or by division in spring

Suggested planting locations and garden types

  • Cottage and informal garden
  • Low Maintenance

Pruning

No pruning required, though the stems may be cut back after flowering

Pests

Generally pest-free

Diseases

May be susceptible to powdery mildews and rust diseases