Scientific Name
Allium giganteum
Common Name
Ornamental Onion
ALLIUM
giganteum (Purple flowers)
A. Flowering Characteristics
A. giganteum flowers in early summer (June/July) and lasts 2-3 weeks. Plants are 35-50 inches tall with a large umbel of densely clumped florets.
B. General Characteristics
1. Origin of species: Himalayas
2. Common names: Ornamental Onion
3. Geophyte organ: Tunicated bulb
4. Hardiness type: Hardy III - Injured below 5 degrees F (-15C) when planted.
5. Natural reproductive systems and growth and development requirements: A. giganteum reproduces by annual daughter bulb replacement and requires a warm (77 to 82F) - cool (28 to 35F) - warm (55 to 65) annual thermoperiodic cycle.
6. Primary uses: Beds, fresh cut flowers, and exhibition bulbs.
C. Cultural Information
1. Bulb sizes: 20/up cm, in circumference.
2. Planting density: 12 inches apart, 1 bulb per sq. ft.
3. Planting depth: 8 inches to base of the bulb.
4. Planting time: Fall
5. Perennialization habit: 1990 USDA Climatic Zone 3 with mulch, Zones 4 to 7 without mulch.
6. Light requirements: Full sunlight to PM only sunlight.
7. Moisture: Tolerates summer drought. Keep moist during growing season.
8. Animal susceptibility: Normally not susceptible.
D. Companion Plants:
Asiatic Hybrid lilies (white and yellow cvs.), Centaurea dealbata, Coreopsis, Dianthus, Digitalis, Gypsophila paniculata, Hemerocallis (yellow cvs.), Iris (rhizomatous white and yellow cvs.), Kniphofia (yellow cvs.), Peonies (white and yellow cvs.), Verbascum (white cvs.), Rhododendron spp. (deciduous and evergreen), Cotoneaster, Berberis, Acer palmatum, Deutzia gracilis, Weigela.

Holland Technical Service Bulletin Number 37 was prepared for the WWW system by A.A. De Hertogh, L.B. Gallitano, G. Hartley, M.E. Traer, and A.B. Russell, Department of Horticultural Science, NC State University. The information was obtained not only from original research conducted by the authors but also from databases released by other sources. This Bulletin was published by the International Flower Bulb Center (IBC), Hillegom, the Netherlands on behalf of the Dutch Flower Bulb Industry. Because of the various climates in North America and year-to-year variability of the weather, the IBC cannot and does not accept responsibility for divergent results that may arise using information obtained from this document or site. Photographs copyright @1997 by A.B. Russell and A.A. De Hertogh. Computer programming by Miguel Buendia, graphics by Brad Capel.