Ornamental onion Allium giganteum Photo/Illustration: Jennifer Benner 1 2 3 4 5 6 7 8 9 10 11 Ornamental onion (Allium giganteum) AL-ee-um jy-GAN-tee-um Genus: Allium In summer, this plant bears large rounded flower heads up to 4 inches across with a multitude of star-shaped lilac-pink flowers. Care: Grow in full sun and dry to average, well-drained soil. Propagation: Sow seed in spring in containers or in situ. Divide clump-forming plants in spring. Problems: Bulb rot in damp conditions. Onion fly and thrips. Overview Height 3 ft. to 6 ft. Spread 1 ft. to 3 ft. Growth Habit Clumps Growth Pace Fast Grower Light Full Sun Only Moisture Dry to Medium Maintenance Low Characteristics Attracts Butterflies, Showy Flowers, Showy Seed Heads Bloom Time Early Summer, Late Spring, Spring, Summer Flower Color Pink, Purple Uses Beds and Borders Style Cottage Garden, Rock Garden Seasonal Interest Summer Interest Type Bulbs Allium giganteumView the discussion thread.