Ornamental Onion is a bulbous herbaceous perennial in the onion family (Amaryllidaceae) native to the Himalaya region and found growing in forests, naturalized areas, and in disturbed areas where it has the potential to be weedy. The plants can grow up to 6 feet tall and 2 feet wide and prefer full sun in well-drained amended garden soil. Plant in fall at a depth of 8 inches and 12 inches apart. A good rule for spacing ornamental onions is one bulb per square foot. Although ornamental onion tolerates summer drought, it should be kept moist during the growing season. The tall stems may need to be staked. The showy pink flowers appear in early summer and lasts 2-3 weeks. It has a large umbel of densely clumped florets composed of small, 6-parted flowers and in a round cluster at the top of a naked stem. Leaves are gray-green in a basal rosette with an onion aroma and start dying back as the plant flowers. It pairs well well with daylilies and low-growing grasses. Plant 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. Bulb mites and bulb rot can occur. VIDEO Created by Elisabeth Meyer for "Edibles, Bulbs, and Houseplants," a plant identification course developed in partnership with Longwood Gardens. More information on Allium .
Curated pairwise relationships between this plant and others in the library — who feeds
whom, who competes, who confuses the pests. Green reads as a good pairing, red as one to avoid.
No curated interactions recorded for this species yet.
Also noted by NC State
Related species the NC State Plant Toolbox flags for this plant — look-alikes to tell
apart, and plants that play a similar role in a planting. Ones we carry in the library are linked.
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
Less than 12 inches
NC region
Coastal; Mountains; Piedmont
Mature size
Height: 1 ft. 0 in. - 6 ft. 0 in. | Width: 1 ft. 0 in. - 2 ft. 0 in.
Growth rate
Medium
Maintenance
Low
Canopy layer
4 - Herbaceous (3-15 ft)
Form & Appearance
Habit / form
Erect
Texture
Medium
Leaf color
Blue; Gray/Silver; Green
Leaf type
Simple
Leaf arrangement
Rosulate
Leaf shape
Linear
Leaf margin
Entire
Leaf value
Fragrant
Leaf size
> 6 inches long, 3-6 inches wide
Hairs present
No
Leaf detail
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.
Flower color
Pink; Purple/Lavender
Flower value
Fragrant; Good Cut; Good Dried; Long-lasting
Flower form
Umbel
Flower shape
Star
Flower size
< 1 inch
Flower detail
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.