Illustration
Blue Giant
Scilla forbesii
Blue Giant blooms from March through March.
Months here are Northern Hemisphere months; in the Southern Hemisphere, shift them by six months.
Growing Blue Giant
Plant it in full sun. It prefers moderate water. It is hardy in USDA zones 3–8. Expect it to reach about 6 in tall and 3 in wide at maturity, in roughly 1 year (a house reading).
Pets
- Not yet checked for pets.
Lists differ and none is complete. If a pet eats a plant and seems unwell, call a veterinarian or a pet poison helpline.
What was checked
Nine facts were checked against named botanical sources, each recorded beside the sources that carried it: mature height and spread, hardiness zones, sun, water, bloom months and color, the trait tags, and years to mature size, which rests on a recorded house rule where no publisher states one and is marked so. Soil, diseases, pests, toxicity and the plant's own names have not yet been read for this plant, and its trait tags are the ones a feature uses rather than every word a page prints. 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 Blue Giant
Blue Giant is a fall-planted bulb: get it in the ground 6 to 8 weeks before the ground freezes, typically September or October in zone 5, the middle of its hardy zones 3 to 8. It pays you back the following March.
Month-by-month timing for your zone is on the planting calendar; if you garden near zone 5, the middle of this plant's hardy range, start with zone 5 in September. Derived from the plant's category, zones and bloom months plus typical zone frost dates, not checked separately.
How big does Blue Giant get?
6 intall5 ft 7 inan adult3 inwideSee Blue Giant 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
Blue Giant's height, spread, hardiness zones, sun, water, bloom months and color and trait tags were checked against 8 published sources on October 22, 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.
- Missouri Botanical Gardenheight, spread, hardiness zones, sun, water, bloom months and color and trait tags
- Chicago Botanic Gardenheight, hardiness zones, sun, water, bloom months and color and trait tags
- University of Wisconsin HorticultureUniversity of Wisconsin-Madison Division of Extensionheight, hardiness zones, sun, bloom months and color and trait tags
- RHSRoyal Horticultural Societysun and bloom months and color
- Chicago Botanic Gardenbloom months and color
- John Scheepersbloom months and color
- Missouri Botanical Gardenbloom months and color
- rvroger.co.ukRV Rogerbloom months and color
How the checking works, and what each standard covers, is on the verified plants page.
Good to know about Blue Giant
Curated from university extensions, botanic gardens and other primary sources, with the source named on every note.
Safety
All parts are poisonous. NC State rates the genus high-severity to humans: eating it can bring mouth pain, nausea, vomiting, cramping, diarrhea and a slowed heartbeat. per NC State
Explore similar plants
You might also like
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.