Allium unifolium
Geophytic perennial native to the coastal ranges of California, Oregon, and Baja California, with 2–3 flat leaves, solitary egg-shaped bulbs, tall round scapes, pink to white flowers, and the RHS Award of Garden Merit.
Common Names
Oneleaf Onion, American Onion, American Garlic, Onion
Summary
One-leaf onion is a compact bulbous perennial native to the western United States, including California and Oregon, grown to 0.1–0.5 m tall with short grey-green basal leaves and an umbel of up to about 20 large, star-shaped pink-purple flowers in late spring, with RHS AGM status and appeal to pollinators.
In cultivation it prefers full sun on fertile, well-drained soil and tolerates chalk, loam, and sand, with alkaline to neutral pH; best grown in containers if garden soil is heavy clay, and propagated by seed when ripe or by offsets after flowering; hardiness H5. It suits cottage/informal gardens, borders and beds, rock gardens, gravel or patio containers, and wildlife gardens.
Lifecycle
Perennial
Height
1–2.5 feet
Spread
1-4 inches
Hardiness Zones
Zones 5-9
Sunlight Requirements
Ideally full sun; tolerates partial shade.
Soil Type
Well-draining loam soil
Soil Drainage
Moist but well-drained soil.
Soil pH
Tolerates all pH levels
Bloom Color
Pink
Bloom Time
Spring.
Foliage Color
Green
Fall Foliage Color
Blue-green, Green
Leaf Lifecycle
Deciduous
Growth Rate
Slow
Seasons of Interest
Spring and Summer
Propagation Methods
Seeds, Division
Attracts Wildlife
Bees, butterflies, and other pollinators.
Taxonomy
- Taxonomic Rank
- Species
- Author
- Kellogg
- Publication
- Proc. Calif. Acad. Sci. 2: 112 (1863)
Superior Taxa
- Kingdom
- Plantae
- Subkingdom
- Pteridobiotina
- Phylum
- Angiosperms
- Order
- Asparagales
- Family
- Amaryllidaceae
- Genus
- Allium
Synonyms
Allium grandisceptrum Allium unifolium Allium unifolium var. lacteum