Illustration
Mount Everest
Allium stipitatum 'Mount Everest'
Also called ornamental onion and flowering onion
Mount Everest blooms from May through June.
Months here are Northern Hemisphere months; in the Southern Hemisphere, shift them by six months.
Growing Mount Everest
Plant it in full sun. It prefers low water. It is hardy in USDA zones 4–8. Expect it to reach about 3.5 ft tall and 0.5 ft wide at maturity, in roughly 1 year (checked).
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 Mount Everest
Mount Everest 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 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 Mount Everest get?
3.5 fttall5 ft 7 inan adult0.5 ftwideSee Mount Everest 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
Mount Everest's height, spread, hardiness zones, sun, water, bloom months and color, years to mature size, trait tags, soil, diseases, pests and toxicity were checked against 15 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.
- John ScheepersAllium stipitatum Mount Everestheight, spread, hardiness zones, sun, water, bloom months and color, years to mature size, trait tags, soil, diseases and pests
- RHSRoyal Horticultural Societyheight, spread, sun, water, bloom months and color, years to mature size, trait tags, soil, diseases and pests
- Chicago Botanic GardenAllium stipitatum 'Mount Everest'height, spread, hardiness zones, sun, water, bloom months and color, trait tags, soil and pests
- colorblends.comColorblends Wholesale Flowerbulbs (Allium Mount Everest)height, spread, hardiness zones, sun, bloom months and color, years to mature size, trait tags, soil and pests
- High Country Gardensheight, spread, hardiness zones, sun, water, bloom months and color, soil, pests and toxicity
- NC State ExtensionAlliumheight, spread, hardiness zones, sun, years to mature size, trait tags, soil, diseases, pests and toxicity
- Pleasant Run NurseryAllium stipitatum 'Mount Everest'height, spread, hardiness zones, sun, water, bloom months and color, trait tags and pests
- fedcoseeds.comFedco Seeds (Mount Everest Tall Allium)height, hardiness zones, sun, bloom months and color, years to mature size and trait tags
- netherlandbulb.comNetherland Bulb Companyheight, spread, hardiness zones, sun, water and bloom months and color
- Iowa State University Extensionand Outreach, Yard and Gardenwater, years to mature size, soil, diseases and pests
- American Meadowsheight, hardiness zones, water and toxicity
- goldenvalleyplants.co.ukGolden Valley Plants (Allium stipitatum 'Mount Everest')height, sun and trait tags
- Van EngelenAllium stipitatum Mount Everestheight, hardiness zones and trait tags
- forttryonparktrust.orgFort Tryon Park Conservancy (New York City), Heather Garden Plant Finderbloom months and color
- Chicago Botanic GardenPlant Finderwater
How the checking works, and what each standard covers, is on the verified plants page.
Good to know about Mount Everest
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.