Illustration
Drumstick Allium
Allium sphaerocephalon
Also called ornamental onion, flowering onion and round headed leek
Drumstick Allium blooms from June through July.
Months here are Northern Hemisphere months; in the Southern Hemisphere, shift them by six months.
Growing Drumstick Allium
Plant it in full sun. It prefers low water. It is hardy in USDA zones 4–8. Expect it to reach about 2.5 ft tall and 1 ft wide at maturity, in roughly 1 year (a house reading).
What was checked
Mature height and spread, hardiness zones, sun, water, bloom months and color and the trait tags were checked against named botanical sources for this plant, with what the sources could not settle written down; years to mature size rests on a recorded house rule where no publisher states one, and is marked so; its common name and alternate names have not been checked yet. Each fact above carries its own mark. The planting, spacing and size sections are derived from these checked facts by a fixed rule, not checked separately, and the plant type is the library's own classification.
When to plant Drumstick Allium
Drumstick Allium is a fall-planted bulb: get it in the ground 6 to 8 weeks before the ground freezes, typically September or October in zone 6, the middle of its hardy zones 4 to 8. It pays you back the following June to July.
Month-by-month timing for your zone is on the planting calendar; if you garden near zone 6, the middle of this plant's hardy range, start with zone 6 in September. Derived from the plant's category, zones and bloom months plus typical zone frost dates, not checked separately.
How big does Drumstick Allium get?
2.5 fttall5 ft 7 inan adult1 ftwideSee Drumstick Allium in a garden plan: the planner shows it in 3D beside everything else you add, growing toward this size over the years.
Where these facts come from
Drumstick Allium's height, spread, hardiness zones, sun, water, bloom months and color, trait tags, soil, diseases, pests and toxicity were checked against 10 published sources on August 23, 2026. Each one is linked below with every fact it carried, which can include a fact this page still marks as not yet checked, because a source carrying a value is not the same as the value being held to the standard. Facts not in that list, and the planting, spacing and size sections, are not covered by these sources.
- NC State ExtensionPlant Toolboxheight, spread, hardiness zones, sun, water, bloom months and color, trait tags, soil, diseases, pests and toxicity
- Missouri Botanical GardenPlant Finderheight, spread, hardiness zones, sun, water, bloom months and color, trait tags, soil, diseases and pests
- Chicago Botanic GardenPlant Finderheight, spread, hardiness zones, sun, water, bloom months and color, soil and pests
- RHSRoyal Horticultural Societyheight, spread, sun, water, bloom months and color, soil, diseases and pests
- Holland Bulb Farmsheight, spread, hardiness zones, sun, water, bloom months and color and soil
- colorblends.comColorblends Wholesale Flowerbulbsheight, hardiness zones, sun, bloom months and color, soil and pests
- Iowa State University Extensionand Outreach, Yard and Gardenheight, sun, bloom months and color, soil, diseases and pests
- Clemson Home and Garden Information CenterClemson Cooperative Extension Home and Garden Information Centerbloom months and color, soil and diseases
- heritageflowerfarm.comHeritage Flower Farmbloom months and color
- ASPCAAnimal Poison Controltoxicity
How the checking works, and what each standard covers, is on the verified plants page.
Good to know about Drumstick Allium
Curated from university extensions, botanic gardens and other primary sources, with the source named on every note.
Safety
Toxic to dogs, cats and horses: onion-family compounds damage red blood cells, causing Heinz-body hemolytic anemia. Cats are the most sensitive, and signs can lag days. per ASPCA and Merck
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Design a garden with this
Drop this plant onto a 3D plan, see how it fills in, and watch your whole garden bloom across the year.