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Allium sphaerocephalon
  • RHS AGM
  • RHS Plants for pollinators

round-headed leek

A tall perennial with a tuft of narrow basal leaves to 30cm long, and long-stalked, dense, rounded heads of pink or reddish-brown flowers in summer

Other common names
round-headed garlic
Synonyms
Allium cilicicum misapplied
Allium descendens
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Size
Ultimate height
0.5–1 metres
Time to ultimate height
2–5 years
Ultimate spread
0.1–0.5 metres
Growing conditions
Chalk
Clay
Loam
Sand
Moisture
Moist but well–drained, Well–drained
pH
Acid, Alkaline, Neutral
Colour & scent
StemFlowerFoliageFruit
Spring Green
Summer Brown Pink Green
Autumn
Winter
Position
  • Full sun
Aspect

South–facing or North–facing or West–facing or East–facing

Exposure
Sheltered
Hardiness
H6
Botanical details
Family
Amaryllidaceae
Native to the UK
Yes
Foliage
Deciduous
Habit
Bushy
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

Plant range
Eurasia, Africa

How to grow

Cultivation

Easy to grow in fertile well-drained soil. Add grit when grown in clay soils to improve drainage. See allium cultivation for further advice

Propagation

Propagate by seed, sowing in containers in a cold frame when just ripe or in the spring. Alternatively, remove offsets in autumn

Suggested planting locations and garden types
  • City and courtyard gardens
  • Coastal
  • Cottage and informal garden
  • Patio and container plants
  • Flower borders and beds
Pruning

No pruning required

Pests

Generally pest-free

Diseases

Onion white rot and a downy mildew may occur

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