Allium sphaerocephalon subsp. sphaerocephalon

RHS Plant Profile
round-headed leek

Save a plant

Where do you want to save Allium sphaerocephalon subsp. sphaerocephalon?

Plants I own
Wishlist
Go to My Plants

Synonyms

Allium deseglisei
Allium sphaerocephalon var. descendens

Plants for pollinators
Bulbs

Bulbous herbaceous perennial. Umbels typically 1.5cm across, consisting of tightly packed pink or reddish-purple flowers, produced in summer.

Position

Full sun

Soil Types

Chalk, Loam, Sand, Clay

Max Height

0.1-0.5 metres

Max Spread

0.1-0.5 metres

Size

Time to Maturity
2–5 years
Max Spread
0.1-0.5 metres
Max Height
0.1-0.5 metres

Growing Conditions

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

Position

Full sun
Aspect
East–facing or 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)
H6
Drought Resistance
Yes

Colour & Scent

Season Stem Flower Foliage Fruit
Spring
Summer
Autumn
Winter

Botanical Details

Family
Amaryllidaceae
Native to GB/Ireland
No
Foliage
Deciduous
Habit
Columnar upright
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
Europe, North Africa and Middle East

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
  • Cottage and informal garden
  • Gravel garden
  • Mediterranean climate plants
  • Prairie planting
  • Wildflower meadow
  • Wildlife gardens
  • Flower borders and beds

Pruning

No pruning required

Pests

Generally pest-free

Diseases

May be susceptible to onion white rot and downy mildews