Scientific Name
Allium oreophilum (A. ostrowskianum)
Common Name
Ornamental Onion
ALLIUM
oreophilum (A. ostrowskianum) (Red flowers)
A. Flowering Characteristics
A. oreophilum flowers in spring (May/June) and lasts 2-3 weeks. Plants are 10-12 inches tall with a loose umbel of red flowers.
B. General Characteristics
1. Origin of species: East Turkestan
2. Common names: Ornamental Onion
3. Geophyte organ: Tunicated bulb
4. Hardiness type: Hardy III - Injured at temperatures below 5 degrees F (-15C) when planted.
5. Natural reproductive systems and growth and development requirements: It reproduces by annual daughter bulb replacement and requires a warm (68 to 73F) - cool (28 to 35F) - warm (55 to 65F) annual thermoperiodic cycle.
6. Primary uses: Borders, rock gardens, woodland gardens and ground covers.
C. Cultural Information
1. Bulb sizes: 3.5/4 and 4/up cm, in circumference.
2. Planting density: 2-3 inches apart, 15-25 per sq. ft.
3. Planting depth: 5 inches to base of the bulb.
4. Planting time: Fall
5. Perennialization habit: 1990 USDA Climatic Zone 3 with mulch, 4 to 7 without mulch.
6. Light requirements: Full sunlight to PM only sunlight.
7. Moisture: Tolerates summer drought, but keep moist during growing season.
8. Animal susceptibility: Normally not susceptible.
D. Companion Plants:
Alyssum, Arabis, 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.