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Herbaceous Perennial

Oenothera 'Crown Imperial'
  • RHS Plants for pollinators

evening primrose 'Crown Imperial'

An upright, clump-forming herbaceous perennial 40-50cm high with broad basal leaves and narrow, glossy, bright green stem leaves, green stems topped by clusters of flowers so that the plant looks like a small crown imperial fritillary, and flowers opening from red buds into large, bowl-shaped, vibrant yellow flowers from midsummer; the flowers are sterile so it does not self-seed

Synonyms
Oenothera coryi 'Crown Imperial'
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Size
Ultimate height
0.1–0.5 metres
Time to ultimate height
1–2 years
Ultimate spread
0.1–0.5 metres
Growing conditions
Chalk
Loam
Sand
Moisture
Well–drained
pH
Acid, Alkaline, Neutral
Colour & scent
StemFlowerFoliageFruit
Spring Green Green
Summer Green Yellow Green
Autumn Green Yellow Green
Winter
Position
  • Full sun
Aspect

West–facing or South–facing or East–facing

Exposure
Sheltered
Drought resistance
Yes
Hardiness
H5
Botanical details
Family
Onagraceae
Native to GB / Ireland
No
Foliage
Deciduous
Habit
Columnar upright
Genus

Oenothera can be annuals, biennials or perennials, upright or spreading in habit, with simple or lobed leaves and bowl-shaped, white, yellow or pink flowers over a long period in summer

Name status

Accepted

How to grow

Cultivation

Grow in poor to moderately fertile, very well-drained soil, even stony soil, in full sun

Propagation

Propagate by internodal one-leaf softwood cuttings of unflowered shoots from late spring to midsummer, or by division in early spring

Suggested planting locations and garden types
  • City and courtyard gardens
  • Gravel garden
  • Prairie planting
  • Cottage and informal garden
  • Cut flowers
  • Flower borders and beds
Pruning

No pruning required

Pests

May be susceptible to slugs and aphids

Diseases

May be susceptible to leaf spot, powdery mildews and downy mildews; root rot may be a problem in rich, wet, heavy soil. Generally disease-free

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