Ornamental Onion or Allium
Allium species (LILIACEAE)
Planting and Growing Ornamental Onion
You’ll find everything you need to know to plant and grow ornamental onion or allium in the accompanying table’s tabs:
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- Flowers, foliage, and root structure of ornamental onion or allium
- Season of bloom and planting time for ornamental onion or allium
- Plant hardiness and growing conditions for ornamental onion or allium
- When, how deep, and where to plant ornamental onion or allium
- How to plant ornamental onion or allium
- Watering, fertilizing, care and pests or diseases of ornamental onion or allium
- Landscape and indoor uses of ornamental onion or allium
- Comments about ornamental onion or allium and its features
Growing Ornamental Onion
Summer bulb. Deciduous. About 700 species. Stands 6–60 in. (15–150 cm) tall. Narrow or broad, usually hollow, midlength gray green leaves.
Ornamental Onion Planting and Care Guide
Flowers
Spring–summer. Blue, pink, red, violet, white, yellow. Multiple star-shaped, often fragrant flowers, 1/4–1‑in. (6–25‑mm) wide, form compact or loose clusters, 1–6 in. (25–150 mm) wide, on tall, leafless stems, bearing seed and bulbils.
Best Climates
U.S.D.A. Plant Hardiness Zones 3–10; ground hardy, zones 4–8.
Soil Type and Fertility
Moist to damp, well-drained humus. Fertility: Average. 6.0–7.0 pH.
Where and How to Plant
Autumn in full sun to partial shade. Space 4–12 in. (10–30 cm) apart, 2–8 in. (50–200 mm) deep, depending on species.
Proper Care
Easy. Keep moist winter–spring. Fertilize in spring. Deadhead flowers. Mulch, zones 3–5. Propagate by bulbils, division, offsets in autumn, seed in spring.
Lifting and Storing
Dark, 50–60°F (10–16°C), in net bag or open basket of dry peat moss.
About This Species
Good choice for accents, borders, containers, edgings in cottage, formal, meadow, natural, rock, woodland gardens. Good for drying. Naturalizes. Deer, rodent and disease, pest resistant.
Selected Species of Ornamental Onion
Several ornamental onion species and cultivars provide many choices for height, color, and appearance:
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- Allium aflatunense, pink flowers, 5 ft. (1.5 m)
- Allium atropurpureum, purple flowers, 30 in. (75 cm)
- Blue Allium (Allium caeruleum), blue flowers, 1 ft. (30 cm)
- Allium carinatum var. pulchellum, red purple flowers, 2 ft. (60 cm)
- Nodding Onion (Allium cernuum), pink flowers, 18 in. (45 cm)
- Stars-of-Persia (Allium christophii), blue flowers, 16 in. (40 cm)
- Allium flavum, yellow flowers, 1 ft. (30 cm)
- Giant Allium (Allium giganteum), blue violet flowers, 4 ft. (1.2 m)
- Allium karataviense, white flowers, 6 in. (15 cm)
- Allium macleanii, Purple flowers, 4 ft. (1.2 m)
- Golden Garlic (Allium moly), yellow flowers, 18 in. (45 cm)
- Allium narcissiflorum, deep pink flowers, 1 ft. (30 cm)
- Daffodil Garlic (Allium neapolitanum), white flowers, 1 ft. (30 cm)
- Allium oreophilum, bright pink flowers, 6 in. (15 cm)
- Allium rosenbachianum ‘Album’, violet flowers, 1 ft. (30 cm)
- Allium roseum, pink flowers, 10–24 in. (25–60 cm)
- Chives (Allium sphaerocephalon), purple flowers, 3 ft. (90 cm)
- Allium triquetrum, white flowers, 1 ft. (30 cm)
- Garlic Chive (Allium tuberosum), white, green flowers, 18 in. (45 cm)
- Allium unifolium, pink flowers, 16 in. (40 cm)
About Ornamental Onion
Between 400 and 500 species and numerous hybrids in the genus Allium are beautiful flowering bulbs grown in landscapes. They include chive, garlic, leek, onion, and shallot.
All are spring- or summer-bloomers, with bulbous or rhizomatous roots. Members of the ornamental onion family have distinctive pom-pom-like or clustered flowers on long, hollow stalks. They flower in colors that range from blue and red to yellow.
In the landscape, ornamental onion bulbs are eye catching for their unusual form.
Use them for massed plantings, edgings, borders, and in container plantings in full sun to partial shade. They are hardy to very cold temperatures if mulched in the autumn.
Choose from the commonly available species and cultivars listed above.