Also known as Ball-Head Onion · Drumstick Allium · Drumstick Onion
Allium sphaerocephalon, the Round-headed Leek, is a striking ornamental onion producing dense, globe-shaped clusters of rosy-purple flowers atop tall stems.
At-a-glance light, water, soil, and growing conditions from plant data
Full Sun
100% intensity
Prefers full sun for best flowering and bulb development. Can tolerate partial shade.
Moderate
50% intensity
Water thoroughly when the top inch of soil is dry. Reduce watering during dormancy.
Well-drained, Sandy, Loam
50% intensity
Moderate
50% intensity
Prefers moderate temperatures during the growing season. Hardy to cold winters, requiring a dry dormancy period.
Low
25% intensity
Fertilize sparingly in spring with a balanced fertilizer. Avoid over-fertilization.
Safety information from plant toxicity data
| Attribute | Value |
|---|---|
| Toxic for humans | No 0/5 intensity |
| Toxic for pets | No 0/5 intensity |
| Edible | Yes |
None
Key traits and growing stats from plant data
Watering, pruning, propagation, and repotting details from plant data
Water regularly during the growing season, especially in dry periods. Allow the soil to dry out slightly between waterings.
Reduce watering significantly once the foliage begins to yellow and die back after flowering, as the bulbs need a dry rest period.
Remove dead or dying foliage only after it has completely yellowed and withered. This allows the plant to reabsorb nutrients into the bulb.
Spent flower stalks can be cut back to the ground once they have faded to maintain a tidy appearance.
Propagate by dividing overcrowded clumps of bulbs in late summer or early autumn, after the foliage has died back. You can also collect seeds from dried flower heads and sow them in autumn or spring, though this method is slower.
Repotting is generally not necessary for outdoor plantings. For container-grown plants, repot every 2-3 years in late summer or early autumn to refresh the soil and divide any crowded bulbs.
Use a well-draining potting mix.
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Monthly activity intensity for bloom and fruit across both hemispheres.
Flowering & fruiting calendar
Flowering & fruiting calendar
Photos of Round-Headed Leek (Allium sphaerocephalon)
Common names and botanical synonyms
Botanical classification
| Rank | Name |
|---|---|
| kingdom | Plantae |
| division | Tracheophyta |
| class | Liliopsida |
| order | Asparagales |
| family | Amaryllidaceae |
| genus | Allium |
| species | Allium sphaerocephalon |
Answers based on plant encyclopedia data
