The Weed Wire: Three-Cornered Garlic
Photo By aaronliston, CC-BY-4.0
History and Native Range: Allium triquetrum- commonly known as three-cornered garlic, three-cornered leek, snowbell, or onion weed- is a bulb-producing, spring-flowering plant native to the Mediterranean basin. In its native range, three-cornered garlic is widely found in meadows, forest clearings, streambanks, and roadsides below 2,800 feet in elevation. It is a commonly cultivated plant due to its attractive flowers, ease of care, and edibility. Through cultivation, three-cornered garlic has now been introduced to Great Britain, Ireland, Portugal, Turkey, New Zealand, Australia, California, Oregon, and South America.
Identification: While three-cornered garlic bears a resemblance to a number of introduced ornamental plants, particularly the white-blooming variant of the similarly weedy Spanish bluebell, three-cornered garlic is not easily confused with any wildflower native to the Oregon coast. A. triquetrum can be differentiated from similar white-blooming plants by the triangular cross-section of its stem, for which it is named, as well as the thin green stripes radiating from the center of its flowers. Additionally, all parts of the plant emit a characteristic garlic-y scent when crushed.
The Problem Here: Being a hardy, adaptable, fast-growing plant, three-cornered garlic has grown out of control in many areas where it has escaped cultivation. In some areas it may form dense monocultures which crowd out native groundcover species or wildflowers of similar size. Even in gardens where three-cornered garlic has been planted as a desired species, the plant may rapidly take over and drown out other ornamentals planted nearby. Three-cornered garlic can be very difficult to keep contained to intentionally planted areas, as one of the main dispersal mechanisms employed by the plant is to secrete a chemical which attracts ants to its seeds, gathering and transporting them to new locations.
An additional matter of concern to note is that, like all alliums, three-cornered garlic is toxic to dogs, cats, and livestock such as cows and horses if ingested.
While three-cornered garlic hasn’t been on the list of noxious weed species frequently controlled by the Lincoln SWCD, in recent years populations around Lincoln County have reached concerning levels of growth, prompting discussion from local noxious weed control specialists about beginning coordinated treatments of the species.
A. Triquetrum monoculture. Matthew Paul Argall via Flickr, CC BY 2.0
Manual Control: Digging or hand-pulling of three-cornered garlic can be an effective method of removal, though labor-intensive for larger patches. Bulbs are shallowly rooted and form mats, which in soft soil may be lifted up with a spade to remove large numbers of plants at once. However, repeated digging or hand-pulling of the same spots is likely required over a succession of years in order to fully eradicate a population. Removed plant material and soil should only be disposed of in landfill garbage to prevent further spread. Mowing the plant before it can produce seed is also helpful in preventing the spread of existing patches.
Herbicides: If one needs to control large amounts of three-cornered garlic in a relatively short period of time, herbicide application can be an effective method of control. Care should be taken to select an herbicide that is effective against alliums and approved for aquatic usage, due to the plant’s tendency to grow in moist areas. 2,4-D and glyphosate-based herbicides have been proven effective in treating alliums. ALWAYS follow label directions when using herbicides, and consult a professional if unsure whether your chosen product or method of application is safe.
Cultural Control: Tarping over three-cornered garlic infestations for multiple growing seasons may be an effective method of eradication, but currently available information is not conclusive. Livestock animals like sheep and goats may be able to safely graze on alliums, but information on the toxicity to these animals is also not definitive.
Links to Information and Studies:
Eat Your Invasives!
As all parts of the three-cornered garlic plant are edible, controlling infestations by foraging is popular in many regions where it grows invasively. Bulbs, leaves, and stems are eaten either raw or sauteed, and fresh flowers make a tasty and attractive garnish on salads and stir frys. Though three-cornered garlic has a milder flavor than more commonly eaten alliums such as spring or green onions, they can be cooked in a similar fashion. If you’re looking to rein in an Allium triquetrum population near you, consider getting a bit of free produce out of it as well! There are many folk recipes for this species out there.
Three-Cornered Garlic Butter:
1 stick salted butter, softened
½ oz three-cornered garlic leaves
Add softened butter to a mixing bowl. After thoroughly washing the garlic leaves, chop them as finely as desired, then add to mixing bowl and mix until evenly distributed through the butter. Then wrap into a roll with parchment paper or store in a covered dish. Use in anything you might use traditional garlic butter, such as in garlic bread or on steak.
Only harvest and consume wild-growing plants from areas you know have not been chemically treated, and for which you have a positive identification.
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Our next board meeting will be held on May 14, 2026 via Zoom. These meetings cover the general business of LSWCD, while also convening to decide the next steps the District will take in overall operations or within specific programs.
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