Overview
Allium unifolium is a bulbous perennial in the Amaryllidaceae family, native to coastal and near-coastal areas of Oregon and California. Plants grow 12–24 inches (30–60 cm) tall from a small ovoid bulb 0.5–0.75 inch (12–18 mm) in diameter. Despite the epithet unifolium (one-leaved), plants typically produce 2–3 flat, strap-shaped, bright green leaves 8–14 inches (20–35 cm) long and 0.3–0.5 inch (8–12 mm) wide — the name refers to the single leaf at each growing point in some populations. The inflorescence is a compact, dome-shaped umbel 2–3 inches (5–8 cm) across, bearing 15–30 bell-shaped to star-shaped flowers, each 0.4–0.6 inch (10–15 mm) long, in soft pink to rose-pink with a darker midvein. Flower colour is consistently pink — unlike many Allium species that come in white, purple, or yellow. Flowers have a mild, sweet scent without the typical pungent onion odour. The species occurs in heavy clay soils in seasonally wet grasslands and open woodland — a habitat type that is wet in winter-spring and dry-baked in summer. This adaptation to clay and seasonal moisture makes it one of the easier native Allium species for Pacific Northwest garden culture. Bulbs go dormant after flowering, with foliage dying back by midsummer. Multiplies readily by offset bulbs, forming dense colonies over 3–5 years.
Native Range
Allium unifolium is native to the Pacific coast of North America, from southwestern Oregon through the California Coast Ranges and into the San Francisco Bay Area. It occurs in heavy clay soils in seasonally wet meadows, grasslands, and open woodland from near sea level to approximately 2,500 feet (750 m).Suggested Uses
Planted in native plant gardens, meadow plantings, and perennial borders, spaced 3–4 inches (8–10 cm) apart in groups of 15–25 for a drift effect. Effective in heavy clay soils where other bulbs fail. Used in Pacific Northwest native plant restoration in seasonally wet grassland habitats. Combines with Camassia, Sidalcea, and native grasses in spring meadow plantings. Suitable for containers (minimum 2 gallons / 7.5 L).How to Identify
Appearance
Size & Dimensions
Height1' - 2'
Width/Spread3" - 6"
Reaches mature size in approximately 2 years
Bloom Information
Flowers open from late April through June, depending on location and season. Each umbel of 15–30 flowers opens over 2–3 weeks. Individual flowers last 5–7 days. Bloom period is approximately 3 weeks. Pollinated by native bees and other insects. Foliage begins to yellow shortly after flowering and is fully dormant by midsummer.Detailed Descriptions
Flower Description
Soft pink to rose-pinkFoliage Description
Bright greenGrowing Conditions
Sun Requirements
Requires 5-10 hours of direct sunlight daily
• Full Sun: 6+ hours of direct sunlight
• Partial Shade: 3-6 hours of direct sunlight
• Full Shade: Less than 3 hours of direct sunlight
Care & Maintenance
Care Guide
Plant bulbs 3–4 inches (8–10 cm) deep and 3–4 inches (8–10 cm) apart in autumn. Site in full sun to light shade in moist, heavy clay to loam soil with a pH of 5.5–7.0 — one of the few ornamental alliums that thrives in clay. Water regularly during the growing season (autumn through spring); allow soil to dry during summer dormancy. No fertilisation needed. Bulbs multiply readily — divide congested clumps every 4–5 years in autumn after dormancy. In the Pacific Northwest, this is one of the most garden-friendly native Allium species due to its clay tolerance and reliable bloom.Pruning
Allow foliage to yellow and die back naturally after flowering — do not remove green leaves. Cut dead foliage at ground level in midsummer. No other pruning required.Pruning Schedule
J
F
M
A
M
J
J
A
S
O
N
D
summer
Maintenance Level
very lowContainer Growing
✓ Suitable for container growing
Minimum container size: 2 gallons