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    Allium Giganteum

    Allium Giganteum

    Giant Ornamental Onion

    $15.00
    $15.00
    Sale Sold out
    Taxes included.
    Pot Size/Grade

    Allium giganteum, commonly known as the Giant Ornamental Onion, is one of the most dramatic flowering bulbs you can grow. Producing enormous spherical flower heads packed with hundreds of star-shaped violet-purple flowers, it creates a breathtaking display in late spring and early summer.

    Held high above the foliage on sturdy stems, the flower heads appear to float through the garden, adding height, structure and architectural interest. Allium giganteum is a favourite in cottage gardens, formal borders and contemporary landscapes, where its unique flowers provide a striking focal point and attract bees in abundance.

    Why You'll Love Allium giganteum

    • Huge globe-shaped violet-purple flower heads
    • Outstanding architectural presence
    • Excellent cut and dried flower
    • Attracts bees and beneficial pollinators
    • Creates height and structure in borders
    • Highly frost hardy
    • Easy to grow and long-lived
    • Beautiful seed heads provide extended interest

    • Expected 5 Year Height 1.8 M Width 0.4 M

    Is Allium Giganteum suitable for my garden?

    Allium Giganteum is best suited in a position that gets

    • Full sun

    Allium Giganteum is

    • Winter Dormant
    • Perennial
    • Frost Tolerant
    • Drought resistant
    • Flowering
    • Fast-growing
    • Cold hardy

    Allium Giganteum will thrive in soil that is

    • Chalky
    • Normal
    • Free draining
    • Nutrient rich

    How to establish your Allium Giganteum?

    Plant Allium giganteum in a full sun position.

    For best flowering:

    Choose a location with at least six hours of direct sunlight daily.
    Ensure good air circulation.
    Avoid heavily shaded areas.

    Full sun encourages strong stems and larger flower heads.

    How to maintain your Allium Giganteum once established?

    Water occasionally during dry periods while foliage and flowers are developing.

    Reduce watering once foliage begins to yellow and die back.

    The bulbs prefer drier conditions during dormancy.

    For strong flowering:

    Apply compost or bulb fertiliser in early spring.
    Feed after flowering to help bulbs store energy for the following season.
    Avoid excessive nitrogen-rich fertilisers.

    After flowering:

    Option 1 – Remove Flower Heads
    Cut flower stems once flowers fade.
    Maintain a tidy appearance.
    Option 2 – Leave Seed Heads
    Retain the decorative seed heads.
    Enjoy months of additional architectural interest.

    Many gardeners choose to leave the seed heads standing.

    The foliage often begins to yellow before flowering reaches its peak.
    This is normal.

    Do not remove leaves until they have fully died back, as they help replenish the bulb for next season's growth.

    Consider underplanting with lower-growing perennials to help disguise aging foliage.

    Allium giganteum is highly frost hardy and performs exceptionally well throughout New Zealand.

    Winter care is minimal:

    Ensure good drainage.
    Leave bulbs undisturbed where possible.
    Apply mulch lightly in very cold regions if desired.
    Growing in Containers

    Allium giganteum can be grown successfully in large containers.

    For best results:

    Use a premium free-draining potting mix.
    Ensure containers have excellent drainage.
    Position in full sun.
    Feed annually during active growth.
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