Allium sphaerocephalon (round-headed leek) — Bushy

Overview

Allium sphaerocephalon is a bushy bulbs in the genus Allium, part of the Amaryllidaceae family, with deciduous foliage. It typically grows around 0.5-1 metres tall and 0.1-0.5 metres wide, reaching full size in around 2-5 years. Allium sphaerocephalon grows best in full sun, and tolerates most soils and any pH. Its UK hardiness is rated H6. Suggested uses include wildlife gardens and wildflower meadows. It is native to Albania, Algeria, Austria, Baleares, Belgium, Bulgaria, Canary Is., Central European Russia, Corse, Cyprus, Czechia-Slovakia and East Aegean Is..

About

Allium sphaerocephalon is a plant species in the Amaryllis family known as round-headed leek, round-headed garlic, ball-head onion, and other variations on these names. Drumstick allium is another common name applied to this species. It is a bulbous herbaceous perennial plant. Allium sphaerocephalon is found in the wild across all parts of Europe except in the northern and western countries (Scotland, Ireland, Netherlands, Scandinavia, and the Baltic States). It is native to Albania, Algeria, Austria, Baleares, Belgium and other regions. Mature plants reach roughly 0.5-1 metres tall and 0.1-0.5 metres wide, carrying deciduous foliage. In the garden it prefers full sun and most soil types. It tolerates soil of any pH, moist but well-drained, well-drained conditions and south-facing, north-facing, west-facing and east-facing aspects.

Wikipedia contributors, CC BY-SA 4.0 — Allium sphaerocephalon

About the genus

Allium is a large genus of monocotyledonous flowering plants with 1112 accepted species, making Allium the largest genus in the family Amaryllidaceae and among the largest plant genera in the world. Many of the species are edible, and some have a long history of cultivation and human consumption such as the onion, garlic, scallions, shallots, leeks, and chives.

Wikipedia contributors, "Allium", CC BY-SA 4.0 — Allium

Growing conditions

Best soil and position for Allium

Sunlight: Full sun
Soil type: Chalk, Clay, Loam, Sand
Soil pH: Acid, Alkaline, Neutral
Soil moisture: Moist but well-drained, Well-drained
Aspect: South-facing, North-facing, West-facing, East-facing
Exposure: Sheltered
UK hardiness: H6

Plant details

Allium sphaerocephalon size, habit and characteristics

Plant type: Bulbs
Habit: Bushy
Foliage: Deciduous
Height: 0.5-1 metres
Spread: 0.1-0.5 metres
Time to full height: 2-5 years
Suggested uses: Wildlife gardens, Wildflower meadows
Native to: Albania, Algeria, Austria, Baleares, Belgium, Bulgaria, Canary Is., Central European Russia, Corse, Cyprus, Czechia-Slovakia, East Aegean Is.

Care notes

Pruning and caring for Allium sphaerocephalon

Cultivation: Plant bulbs in autumn in well-drained soil with full sun exposure; minimal maintenance required; avoid waterlogged conditions
Pruning: Remove spent flower heads to prevent self-seeding; cut back foliage after it yellows and dies back naturally
Propagation: Seed, Division
Pest resistance: Generally pest-free
Disease resistance: Onion white rot, Downy mildews

Frequently asked questions

How do I grow Allium sphaerocephalon?

Plant bulbs in autumn in well-drained soil with full sun exposure; minimal maintenance required; avoid waterlogged conditions.

Where is the best place to plant Allium sphaerocephalon?

Allium sphaerocephalon prefers full sun. It suits sheltered positions.

What soil does Allium sphaerocephalon need?

Allium sphaerocephalon is adaptable and grows happily in most soil types, including chalk, clay, loam and sand. It is happy in soil of any pH. Aim for soil that stays moist but well-drained to well-drained.