Alphabetical Plant Listing

Allium giganteum (Ornamental Onion)

Ornamental Onion, Ornamental Garlic, Giant Onion, Giant Allium, Spring Bulbs, Spring Flowers


Perhaps the tallest of the ornamental onions, Allium giganteum is a bold and striking addition to the garden with its star-shaped, tiny lilac-purple flowers forming a 5-6 in. wide (12-15 cm) globe-shaped cluster. Blooming in late spring to early summer, this Giant Allium enjoys long-lasting blooms and remains ornamental in the garden well into summer. This bulbous perennial makes a perfect background plant that you may want to combine with finer-textured plants such as ornamental grasses. Great in fresh or dried flower arrangements too!

  • Recipient of the prestigious Award of Garden Merit by the Royal Horticultural Society
  • Grows up to 5-6 ft. tall (150-180 cm). Allium giganteum naturalizes easily and will come back year after year!
  • Easily grown in rich, sandy to gritty, dry to medium moisture, well-drained soils in full sun. This Allium is drought tolerant.
  • Known for attracting bees, butterflies, ​moths, and other pollinators, but deer ignore it.
  • Stunning in beds, borders, and cottage gardens. Spectacular in large sweeping drifts. Plant in groups (at least 10 to 15 bulbs) for the best visual impact. Excellent as cut flowers for both fresh and dried arrangements!
  • Mixes beautifully with other late spring flowering bulbs and creates stunning combinations with pink or white delphiniums, peonies, or irises.
  • To be planted in fall.

Hundreds of Allium species exist, but only a few have made a name for themselves as garden plants. The ornamental onions distinguish themselves by their remarkable 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. Certain small species are just perfect for a rock garden, and several lend themselves to naturalizing. All species can be used in the border.

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.

Read More

Not sure which Allium to pick?
Compare All Allium

Buy Allium giganteum (Ornamental Onion)

Requirements

Hardiness 6 – 10
Heat Zones 5 – 9
Climate Zones 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 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 5' – 6' (150cm – 180cm)
Spread 1' – 2' (30cm – 60cm)
Spacing 8" (20cm)
Depth 8" (20cm)
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 Dried Arrangements, Cut Flowers, Fragrant, Plant of Merit, Showy
Tolerance Deer, Drought, Rabbit
Attracts Butterflies
Garden Uses Beds and Borders
Garden Styles Formal Garden, Informal and Cottage

Buy Plants

Great Plant Combination Ideas with Allium

Guides with Allium


©Clive Nichols

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 6 – 10
Heat Zones 5 – 9
Climate Zones 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 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 5' – 6' (150cm – 180cm)
Spread 1' – 2' (30cm – 60cm)
Spacing 8" (20cm)
Depth 8" (20cm)
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 Dried Arrangements, Cut Flowers, Fragrant, Plant of Merit, Showy
Tolerance Deer, Drought, Rabbit
Attracts Butterflies
Garden Uses Beds and Borders
Garden Styles Formal Garden, Informal and Cottage

Great Plant Combination Ideas with Allium

Guides with Allium

Plant Calculator

How many Allium giganteum (Ornamental Onion) do I need for my garden?

%
ft
ft

Your Shopping List

Plant Quantity
Allium giganteum (Ornamental Onion)

Find your Hardiness Zone

Find your Climate Zone

Find your Heat Zone

Join Gardenia.net

Create a membership account to save your garden designs and to view them on any device.

Becoming a contributing member of Gardenia is easy and can be done in just a few minutes. If you provide us with your name, email address and the payment of a modest $25 annual membership fee, you will become a full member, enabling you to design and save up to 25 of your garden design ideas.

Join now and start creating your dream garden!

Create a New Collection

Optional. For your reference.


Move Selected Plants to a Different Collection


Delete Collection

This field is required.

Rename Collection

This field is required.