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Allium rosenbachianum Regel
  • RHS Plants for pollinators

showy Persian onion

Bulbous perennial about 1m tall, with strap-shaped, grey-green basal leaves to 30cm long. In early summer, the tall flowering stems carry large, globular heads of tightly packed, star-shaped, reddish-purple flowers to 10cm across, with prominent violet stamens

Synonyms
Allium rosenbachianum subsp. rosenbachianum
Allium angustipetalum
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Size
Ultimate height
0.5–1 metres
Time to ultimate height
1–2 years
Ultimate spread
0.1–0.5 metres
Growing conditions
Chalk
Loam
Sand
Moisture
Moist but well–drained, Well–drained
pH
Acid, Alkaline, Neutral
Colour & scent
StemFlowerFoliageFruit
Spring Grey Silver Green
Summer Red Purple Grey Silver Green
Autumn
Winter
Position
  • Full sun
Aspect

South–facing or West–facing

Exposure
Sheltered
Hardiness
H5
Botanical details
Family
Amaryllidaceae
Native to GB / Ireland
No
Foliage
Deciduous
Habit
Clump forming
Genus

Allium are bulbous herbaceous perennials with a strong onion or garlic scent, linear, strap-shaped or cylindrical basal leaves and star-shaped or bell-shaped flowers in an umbel on a leafless stem

Name status

Correct

How to grow

Cultivation

Grow in full sun and fertile well-drained soil. It is best to grow in containers where garden soil is heavy clay and prone to saturation over winter. See allium cultivation

Propagation

Propagate by seed when just ripe or in spring; or propagate by offsets which can be carefully detached by lifting the bulb after flowering has finished. See bulb propagation

Suggested planting locations and garden types
  • Cottage and informal garden
  • City and courtyard gardens
  • Gravel garden
  • Patio and container plants
  • Wildlife gardens
  • Cut flowers
  • Flower borders and beds
Pruning

No pruning required, other than to remove old flowered stems and foliage

Pests

May be susceptible to allium leaf miner and onion fly

Diseases

May be susceptible to onion white rot and onion downy mildew

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