Alphabetical Plant Listing

Allium unifolium (Oneleaf Onion)

Oneleaf Onion, American Onion, Allium grandisceptrum , Ornamental Onion, Spring Bulbs, Spring Flowers


Allium Unifolium (Oneleaf Onion) is a compact perennial with delicate clusters of up to 30 fairly large, star-shaped, satiny, rose-pink flowers. The blossoms are borne atop the foliage of short gray-green basal leaves. Blooming in late spring to early summer, this charming Allium spreads freely in the garden without being a pest.

  • Recipient of the prestigious Award of Garden Merit by the Royal Horticultural Society
  • Grows up to 12-24 in. high (30-60 cm). This Allium naturalizes easily and will slowly spread to form lovely colonies.
  • Easily grown in fertile, dry to medium moisture, well-drained soils in full sun.
  • Stunning in beds and borders, or rock gardens. For best visual impact, plant in groups (at least 20 bulbs).
  • Known for attracting bees, butterflies, and other pollinators, but deer ignore it.
  • To be planted in fall.
  • No serious pest or disease issues. Keep an eye out for onion white rot, and downy mildew.
  • Propagate by seed, sowing seeds in containers with bottom heat when ripe and grow on under glass. Remove offsets in spring and grow on under glass for 2 seasons.
  • Allium Unifolium is native to the coastal mountain ranges of California, Oregon, and Baja California.

Many hundreds of Allium species exist, but only a modest few have made a name for themselves as garden plants. The ornamental onions distinguish themselves by their great diversity in color, inflorescence and flowering height. Many species bloom in early summer - just after the spring-flowering period and just before the exuberant full bloom of summer. All species can be used in the border. Certain small species are just perfect for a rock garden, and several lend themselves to naturalizing.

Learn How To Plant And Care for Your Spring Flower Bulbs

 To achieve optimum flowering results, it is important to plant the bulbs at the right time.

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Requirements

Hardiness 4 – 9
Heat Zones 1 – 9
Climate Zones 3, 3A, 3B, 4, 5, 6, 7, 8, 9, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24
Plant Type Bulbs
Plant Family Allium
Exposure Full Sun
Season of Interest Spring (Late)
Summer (Early)
Height 1' – 2' (30cm – 60cm)
Spread 3" – 4" (7cm – 10cm)
Spacing 2" (5cm)
Depth 4" (10cm)
Water Needs Average
Maintenance Low
Soil Type Chalk, Clay, Loam, Sand
Soil pH Acid, Alkaline, Neutral
Soil Drainage Moist but Well-Drained, Well-Drained
Characteristics Fragrant, Showy
Native Plants United States, California, Pacific Northwest, Oregon
Tolerance Deer, Rabbit
Attracts Butterflies
Garden Uses Beds and Borders
Garden Styles Gravel and Rock Garden

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Great Plant Combination Ideas with Allium

Guides with Allium


While every effort has been made to describe these plants accurately, please keep in mind that height, bloom time, and color may differ in various climates. The description of these plants has been written based on numerous outside resources.


Requirements

Hardiness 4 – 9
Heat Zones 1 – 9
Climate Zones 3, 3A, 3B, 4, 5, 6, 7, 8, 9, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24
Plant Type Bulbs
Plant Family Allium
Exposure Full Sun
Season of Interest Spring (Late)
Summer (Early)
Height 1' – 2' (30cm – 60cm)
Spread 3" – 4" (7cm – 10cm)
Spacing 2" (5cm)
Depth 4" (10cm)
Water Needs Average
Maintenance Low
Soil Type Chalk, Clay, Loam, Sand
Soil pH Acid, Alkaline, Neutral
Soil Drainage Moist but Well-Drained, Well-Drained
Characteristics Fragrant, Showy
Native Plants United States, California, Pacific Northwest, Oregon
Tolerance Deer, Rabbit
Attracts Butterflies
Garden Uses Beds and Borders
Garden Styles Gravel and Rock Garden

Great Plant Combination Ideas with Allium

Guides with Allium

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