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Giant Allium

Allium giganteum

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A stunning ornamental onion producing massive spherical flower heads (inflorescences) of 4–6 inches in diameter, composed of tiny purple-pink florets, on tall 3–5 foot stems. The flowers bloom in late spring and early summer, providing dramatic height and architectural interest to perennial borders. The blooms dry beautifully on the plant and are excellent for fresh and dried arrangements.

Giant Allium

Common Problems

Select the problem your Giant Allium is experiencing to get a treatment guide.

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Underwateringchevron_right
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Root Rotchevron_right
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Slow Growthchevron_right
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Yellow Leaveschevron_right

Care Guide

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Light
Full sun (6–8 hours daily); requires abundant sunlight for robust growth and flowering
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Water
Moderate during growing season; drought-tolerant once established; reduce watering after flowering and during dormancy
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Soil
Well-draining soil is essential; tolerates poor, sandy, or rocky soil; pH 6.0–7.5; poor drainage causes bulb rot
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Fertiliser
Light application of balanced fertilizer (10-10-10) at planting or in early spring; avoid excess nitrogen which reduces flowering
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Temperature
Prefers cool to moderate temperatures; dormant in summer heat; requires cool winter chill for flowering (zone dependent)
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Humidity
Low to moderate; drought-tolerant; no special humidity needs; dislikes wet conditions

Toxicity

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Toxic to cats and dogs due to thiosulfate compounds; can cause hemolytic anemia and gastrointestinal upset if ingested

Common Diseases

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Common Pests

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Seasonal Care

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Resume regular watering and feeding as growth picks up.

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Peak growing season. Water and feed regularly.

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Reduce watering as growth slows. Stop heavy feeding.

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Minimal watering and feeding. Protect from frost if needed.