Ornamental Onions

Did you know that some onions have attractive flowers? There are several species of Allium or onion that are grown exclusively for their flowers instead of their bulbous structures. Ornamental onions (common name for many species) are not planted in the vegetable garden, but in beds or borders with other perennial flowers.

Flower heads on ornamental onions are usually globe shaped and appear in late spring to mid summer. The diameter of the flower heads varies from that of a quarter to a volleyball. When blooming, many ornamental onions have rather ugly foliage. Therefore, they are often planted behind other smaller perennials that hide the yellowing leaves.

A large number of ornamental onions are available to the home gardener. A few are listed below.

Allium aflatunense 'Purple Sensation' produces violet-purple flower heads the size of a baseball. Flowers appear in late spring or early summer on 20 to 30 inch stems.

Allium caeruleum (azureum) has clear, blue, quarter-size flower heads in early summer. The 12 to 18 inch tall plants freely reseed and naturalize in sunny, undisturbed areas.

Allium christophii has attractive baseball to softball sized flowers on 12 to 20 inch stems. Amethyst purple flowers appear in late spring and often last for 2 to 3 weeks.

For larger, softball size flowers, Allium giganteum, attracts attention in the garden. This onion has pale purple flowers in late spring on 40-inch stems. 'White Giant' is a white flowering form.

'Gladiator' has bluish purple flowers that are equally as large as A. giganteum. They appear in early summer on 36 to 48 inch stems.

The largest flower heads, however, are often produced on 'Globemaster.' The softball to volleyball size heads are composed of hundreds of tiny pinkish-purple flowers and are borne on 24 to 36 inch stems. 'Globemaster' blooms in early summer.

Another giant flowering onion is Allium shubertii. The loose and open flowers appear in late spring on 12 to 24 inch stems. They approach the size of volleyballs. Individual flowers are rosy purple.

'Ivory Queen' is only 6 inches tall with whitish flowers in late spring. Its attractive, dark green leaves complement the baseball-size flower heads.

Allium karataviense is another ornamental onion with attractive foliage. The gray-blue foliage serves as a colorful backdrop to the lilac colored flower heads before they disappear in late summer. The golf ball size flower heads are borne atop 8 to 12 inch tall stems.

The bright yellow flowers of Allium moly are unusual for the onion family. The golf ball size flower heads appear in early summer on 10 to 12 inch stems. This onion is aggressive and freely naturalizes in undisturbed areas.

Drumstick allium (Allium sphaerocephalon) has small (quarter-size) flower heads in early summer. Flowers are maroon at the base and fade to purple near the top. Drumstick allium frequently reseeds and forms small colonies in suitable sites.

The flower heads of ornamental onions can be cut and appreciated in vases indoors. Many also dry well. The heads of Allium christophii and Allium karataviense dry a silvery-tan color with little or no effort.

Ornamental onions prefer sunny sites with well-drained soils. Bulbs may rot in soggy or wet soils. Shady sites will produce floppy flowers.

Allium bulbs are often purchased from mail-order catalogs or garden centers. They are planted in fall with tulips and daffodils. Planting depth depends on the size of the bulb. Typically larger bulbs are planted 6 to 8 inches deep while smaller bulbs are planted 3 to 4 inches deep.

A few mail-order sources of ornamental onions are listed below. Or check your local garden center this fall for their selection of ornamental onions. Next May and June you can enjoy their interesting flower heads in your garden. Brent and Becky's Bulbs 7463 Heath Trail Gloucester, VA 23061 804-693-3966 John Scheeper 23 Tulip Drive Bantam, CT 06750 860-567-0838 McClure and Zimmerman 108 W. Winnebago Street Friesland, WI 53935 414-326-4220

This article originally appeared in the May 17, 2002 issue, pp. 65-66.


Cynthia Haynes Professor

Dr. Haynes is a Professor of Horticulture at Iowa State University in Ames.  Her primary responsibilities are in teaching and extension.  She teaches several courses for the Department of Horticulture including Home Horticulture and Herbaceous Ornamentals.  She also has extension r...

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