Giant Ornamental Onion Allium giganteum
Other Common Name(s):
Previously known as:
- Allium procerum
- Phonetic Spelling
- AL-ee-um jy-GAN-tee-um
- This plant has low severity poison characteristics.
- See below
- Description
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Ornamental Onion is a bulbous perennial characterized by its showy pink flowers and its garlic onion fragrance. It generally flowers in early summer and lasts 2-3 weeks. It is 35-50 inches tall with a large umbel of densely clumped florets. Its flowers are small, 6-parted, and in a cluster at the top of a naked stem. Although ornamental onion tolerates summer drought, it should be kept moist during the growing season.
Native to the Himalaya region, this allium can be found growing in forests, naturalized areas, and in disturbed areas where it has the potential to be weedy. In the landscape, it can be a cultivated perennial in flower beds where it does well with daylilies and low-growing grasses. It should be planted at a depth of 8” to the base of the bulb and 12” apart. A good rule for spacing ornamental onion is one bulb per square foot. For best results plant in the fall with access to full sunlight in well-drained soils. This plant will do well near the back of the border in groups of 5-9.
Pests, Insects, and Other Plant Problems: Overly damp conditions leave ornamental onions prone to fungal issues, including a black rot that appears on the leaves and bulbs, destroying the plant.
VIDEO Created by Elisabeth Meyer for "Edibles, Bulbs, and Houseplants" a plant identification course offered in partnership with Longwood Gardens.
- Profile Video:
- See this plant in the following landscape:
- Colorful Borders
- Cultivars / Varieties:
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- Tags:
- Cultivars / Varieties:
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- Tags:
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Attributes:
- Genus:
- Allium
- Species:
- giganteum
- Family:
- Alliaceae
- Life Cycle:
- Bulb
- Perennial
- Recommended Propagation Strategy:
- Division
- Seed
- Country Or Region Of Origin:
- Himalayas, Western and Central Asia
- Play Value:
- Attractive Flowers
- Colorful
- Fragrance
- Particularly Resistant To (Insects/Diseases/Other Problems):
- Typically not susceptible to animals. Drought tolerant.
- Edibility:
- Leaves, bulbs, and bulblets are edible. Gather leaves during spring and fall. Gather bulbs in the second year when they are large enough to use like cultivated onions. Flower stem bulblets are collected during the summer. However, the plant also has poisonous characteristics as noted in the "Poisonous to Humans" section of this record. Toxicity can depend on the age of the person or animal, the age of the plant, the part of the plant ingested, how much is ingested, whether the person or animal has sensitivities or allergies, whether it's eaten raw or cooked, and so forth. Consult with a medical professional for further details.
- Dimensions:
- Height: 1 ft. 0 in. - 6 ft. 0 in.
- Width: 1 ft. 0 in. - 2 ft. 0 in.
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Whole Plant Traits:
- Plant Type:
- Bulb
- Herbaceous Perennial
- Perennial
- Poisonous
- Habit/Form:
- Erect
- Growth Rate:
- Medium
- Maintenance:
- Low
- Texture:
- Medium
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Cultural Conditions:
- Light:
- Full sun (6 or more hours of direct sunlight a day)
- Soil Texture:
- Clay
- Loam (Silt)
- Sand
- Soil pH:
- Acid (<6.0)
- Alkaline (>8.0)
- Neutral (6.0-8.0)
- Soil Drainage:
- Good Drainage
- Available Space To Plant:
- Less than 12 inches
- NC Region:
- Coastal
- Mountains
- Piedmont
- USDA Plant Hardiness Zone:
- 4a, 4b, 5a, 5b, 6a, 6b, 7a, 7b, 8a, 8b
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Fruit:
- Fruit Type:
- Capsule
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Flowers:
- Flower Color:
- Pink
- Purple/Lavender
- Flower Inflorescence:
- Umbel
- Flower Value To Gardener:
- Fragrant
- Good Cut
- Good Dried
- Long-lasting
- Flower Bloom Time:
- Spring
- Summer
- Flower Shape:
- Star
- Flower Petals:
- 6 petals/rays
- Flower Size:
- < 1 inch
- Flower Description:
- The purple star-shaped flowers are small, 6-parted, and in a cluster 5-6 inches wide at the top of a naked stem. Blooms early summer in June-July and lasts 2-3 weeks. Good cut or dried.
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Leaves:
- Leaf Color:
- Blue
- Gray/Silver
- Green
- Leaf Value To Gardener:
- Fragrant
- Leaf Type:
- Simple
- Leaf Arrangement:
- Rosulate
- Leaf Shape:
- Linear
- Leaf Margin:
- Entire
- Hairs Present:
- No
- Leaf Length:
- > 6 inches
- Leaf Width:
- 3-6 inches
- Leaf Description:
- The leaves are long, slender, and strap-like, 2-3 ft. tall and 2-4 in. wide. They come up as a tight, upright cluster and then usually lie flat at the base of the plant. They have a fragrance that resembles garlic or onion. Slightly glaucous, which means that they are green with a tinge of blueish-gray. Often die down shortly after blooming has occurred.
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Stem:
- Stem Color:
- Green
- Stem Is Aromatic:
- No
- Stem Surface:
- Smooth (glabrous)
- Stem Description:
- Sturdy green stem 3-4 feet tall
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Landscape:
- Landscape Location:
- Naturalized Area
- Landscape Theme:
- Cottage Garden
- Cutting Garden
- Drought Tolerant Garden
- Design Feature:
- Accent
- Border
- Small groups
- Attracts:
- Butterflies
- Resistance To Challenges:
- Deer
- Drought
- Rabbits
- Problems:
- Poisonous to Humans
- Problem for Cats
- Problem for Dogs
- Short-lived
- Weedy
