Seven years ago, I wrote a blog on wild onion, Allium triquetrum.[1] Since that time, I've learned that I actually have one type of wild onion in my yard and another plant that initially looks like wild onion or wild garlic, Nothoscordum gracile, but actually is not. It is known as the “slender false garlic” or the “devil bulb.” They are entirely different plants. This blog will focus on Allium triquetrum and its control and my next blog will address the true scourge of my backyard, Nothoscordum gracile.
Allium triquetrum, commonly known as the “three-cornered leek” or “white-flowered onion,” grows only in my front yard. It is a non-native perennial herb that is edible. The wild onion has staggered sprouting times throughout in the winter and, in my yard, generally blooms from February to April. Allium triquetrum has long, thin, green leaves that have a very shallow ‘V' shape and a stem that is more triangular in profile than the leaves, hence the common name, three-cornered leek. The small, white flowers dangle in clusters, each with six petals that have a green stripe. This plant is better behaved in my yard than Nothoscordum gracile, restricting itself to a relatively small area.
I can control Allium triquetrum somewhat by trying to pull the entire plant. One Bay Area reference suggests pulling the wild onions in December or January because you are more likely to pull the entire plant then.[2] But by March, the tops will come away as you pull the plant, leaving the bulbs in the ground. At that point, you have to be more careful to also remove the bulb. Removing the flowers may help reduce seed formation when there isn't time to properly weed. The reference also states that another good time for control is from May through September because the bulbs are visible near the soil surface and can be more easily removed. The bulbs are round, whitish and from tiny to over 1/2 inch in diameter. I've never seen bulbs near the surface because the area is covered with other plants, but I'll be sure to look this year.
While some people suggest harvesting the wild onion for eating or its flowers as a means of control, I'm not interested in doing so. I just want them out of my yard. Moreover, "wild onion" can mean different things to different people. I once thought I had one variety of wild onion in my yard and then I learned that I have different plants entirely. Never eat a plant you haven't identified with certainty.
[1] Mahaney, Erin. “This (Wild) Onion Makes Me Cry!” (April 23, 2012) at https://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=7173.
[2] Peirce, Pam. “Onion lily not easy to get rid of.” (Jan. 20, 2013) at https://www.sfgate.com/homeandgarden/goldengategardener/article/Onion-lily-not-easy-to-get-rid-of-4205813.php.