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Pregnant Onions?

© Julie Finn

New to the area? Want to get to know the neighbors? If so, try introducing pregnant onions. A few specimens, strategically positioned in pots near the front door, will elicit oohs, ahhs and "What the heck is it?" from gardeners and non-gardeners alike.

This delightful oddball, known scientifically as Ornithogalum longibracteatum (syn. O.caudatum), is a real conversation starter. And no wonder--to the uninitiated, the bulb resembles an exploding green volcano. But instead of spewing lava, the long, ribbon-like leaves--apple-green in color--shoot straight from the trunk, then abruptly fall, as if pulled by gravity, and languorously taper to a wisp, some 4 feet away.

Long succulent wands appear in summer, bearing masses of 50 to 100 white, star-shaped, 6-petaled flowers. Interestingly, each petal is divided by a green stripe. Bees find the scentless flowers irresistible.

The common moniker is a reference to its peculiar habit of vegetative reproduction. New bulbs form under the skin and grow to the size of small marbles until they erupt the thin membrane and are "born," so to speak.

Ornithogalum, the genus name, is derived from the Greek ornis, meaning bird, and galum, meaning milk flower. Caudatum, meaning with a tail-like appendage, perfectly describes the thick, sinewy flower stems which snake and twist their way toward some far-off target.

Pregnant onions are members of the Liliaceae; close relatives include the rambunctious spring-blooming Star of Bethlehem, Ornithogalum umbellatum, and the more refined O. thrysoides, the familiar florist's flower. Another rare cousin, O. dubium, sports orange flowers, and is occasionally offered by specialist bulb companies. The International Bulb Society has photos of all three at their Web site. See http://www.bulbsociety.com

Native to the Cape and Natal Provinces of South Africa, this bulbous plant is neither a true onion nor does it come from the sea, as another common name, sea onion, suggests.

Because mature plants attain heights of 3 feet and have flower spikes extending another 2 feet, gardeners often have difficulty placing plants in the garden. This dilemma is easily resolved by growing plants in baskets or containers placed at eye level, where their unique beauty can be appreciated. An added advantage of container cultivation is that bulbs are readily moved indoors when frost threatens.

Cultivation and propagation couldn't be easier. Plant bulbs on the surface of a fast-draining medium such as Pro-Mix. For optimal flower production fertilize bi-monthly with a water-soluble formulation of 15-30-15 during the growing period, early spring through fall. With the onset of cooler (and shorter) days plants will enter a brief period of dormancy. During this time fertilization is ceased and plants are watered sparingly.