Cedar Valley Arboretum & Botanic Gardens

Plant of the Week: Allium

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I always consider spring-flowering bulbs the perfect accessory to a garden – the jewelry that brings a great outfit together.  In the case of Alliums (also called ornamental onions), the dramatic purple flower would certainly be a statement piece to your outfit!


Genus:  Allium

The genus includes over 500 species, with many cultivated as ornamentals and others cultivated as edible crops.  Onions, shallots, garlic, chives and leeks are all found in this genus.

Family:  Alliaceae

The species shown above is Allium giganteum.  As the latin “giganteum” might suggest, this ornamental onion is one of the biggest species.  The softball-size blooms stand atop a stiff stem that is often 3-4 feet tall.  The bloom size and height vary greatly between the species, along with a variety of shades of white, pink and purple blooms.  Basal foliage is more prominent in some species than others.


Allium is relatively easy to grow in well-drained soil and full sun.  When planting taller varieties, it is best to plant in protected areas.  After done blooming, the foliage will soon dieback.  I often leave the spent blooms in my garden for as long as they will stand – the developed seed heads are as interesting to see as the bloom!


As I mentioned before, Allium is a spring-flowering bulb, so must be planted in the previous fall to produce blooms in the spring.  The size of your chosen species (size of your bulbs) will determine planting depth – the label should instruct you on planting.  I suggest planting a handful of Alliums (at least 5-7) for a real “wow” in your garden.

See you in the gardens.


Written by cedarvalleyarboretum

January 12, 2011 at 6:24 pm

Posted in Uncategorized

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