Romneya coulteri

RHS Plant Profile
Californian tree poppy

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Californian tree poppy RHS
Californian tree poppy RHS 2002
Californian tree poppy RHS
Californian tree poppy RHS

Other common names

bush poppy, Californian poppy, canyon poppy, dream of the desert, giant white Californian poppy, Matilija poppy

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Herbaceous Perennial
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A vigorous, suckering herbaceous perennial to 2m in height, with divided, grey-green leaves and poppy-like flowers 15cm in width, with crinkled, pure white petals and a boss of deep yellow stamens

Position

Full sun

Soil Types

Loam, Sand

Max Height

1.5-2.5 metres

Max Spread

1-1.5 metres

Size

Time to Maturity
5–10 years
Max Spread
1-1.5 metres
Max Height
1.5-2.5 metres

Growing Conditions

Loam Sand
Moisture
Moist but well–drained or Well–drained
pH
Acid or Alkaline or Neutral

Position

Full sun
Aspect
South–facing or West–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
Drought Resistance
Yes

Colour & Scent

Season Stem Flower Foliage Fruit
Spring
Summer
Autumn
Winter

Botanical Details

Family
Papaveraceae
Native to GB/Ireland
No
Foliage
Deciduous
Habit
Suckering
Genus
Romneya are suckering subshrubs with pinnately lobed leaves and large white flowers in summer
Name Status
Correct
Plant Range
California, Mexico

How to Grow

Cultivation

Grow against a warm, sunny wall protected from cold winds. Mulch deeply prior to winter. They dislike transplanting but once established it can spread, so site with care

Propagation

Propagate by basal cuttings in spring, root cuttings in winter or propagate by seed sown in spring at 13°C to 16°C

Suggested planting locations and garden types

  • Cottage and informal garden
  • Mediterranean climate plants
  • Wall side borders

Pruning

Pruning group 6

Pests

Caterpillars may be a problem

Diseases

Powdery mildews may be a problem