Illustration
Globemaster
Allium 'Globemaster'
Also called ornamental onion and flowering onion
Globemaster blooms from May through June.
Months here are Northern Hemisphere months; in the Southern Hemisphere, shift them by six months.
Growing Globemaster
Plant it in full sun. It prefers low water. It is hardy in USDA zones 5–8. 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
Fifteen fields were checked against named botanical sources, each recorded beside the sources that carried it, with every unsettled point written down and decided: mature height and spread, hardiness zones, sun, water, bloom months and color, the trait tags, soil, diseases, pests, toxicity, the plant's own names, and years to mature size, which rests on a recorded house rule where no publisher states one and is marked so. 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 Globemaster
Globemaster 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 5 to 8. It pays you back the following May to June.
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 Globemaster get?
2.5 fttall5 ft 7 inan adult1 ftwideSee Globemaster 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
Globemaster's height, spread, hardiness zones, sun, water, bloom months and color, trait tags, soil, diseases, pests and toxicity were checked against 11 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, bloom months and color, years to mature size, 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
- RHSRoyal Horticultural Society (RHS)height, spread, sun, bloom months and color, years to mature size, trait tags, soil, diseases and pests
- Chicago Botanic GardenPlant Finderheight, hardiness zones, sun, water, bloom months and color, trait tags and pests
- John ScheepersBeauty from Bulbsheight, hardiness zones, sun, water, trait tags, soil and pests
- dutchgrown.comDutchGrownheight, hardiness zones, sun, bloom months and color and trait tags
- fedcoseeds.comFedco Seedsheight, hardiness zones, sun, bloom months and color and trait tags
- Iowa State University Extensionand Outreach, Yard and Gardenheight, bloom months and color, trait tags, soil and pests
- Longfield Gardensheight, spread and hardiness zones
- Van EngelenREPRINT of the John Scheepers copy, same firm, treat as ONE voice with...height, hardiness zones and trait tags
- ASPCAAnimal Poison Controltoxicity
How the checking works, and what each standard covers, is on the verified plants page.
Good to know about Globemaster
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.