Evan X. Merz

One of the most common weeds in California gardens is Oxalis Pes-Caprae, aka Bermuda Buttercup. I usually refer to it by the name "Oxalis", but this is a really poor way to describe it because Oxalis is a genus of plants. There are many species of Oxalis, aka wood sorrels, that are native to California, such as Oxalis Oregana, aka Redwood Sorrel. Still, for the rest of this article I'm going to use the name Oxalis to refer only to the one I see most commonly in the garden: Oxalis pes-caprae.

Oxalis pes-caprae is an easy plant to love, despite it's weedy nature. It's edible, and has a pleasant sour flavor. Some foragers like to use it like lettuce in salads. It also puts on a beautiful display of small, vibrant yellow flowers. For this reason, the Oxalis bloom in the late winter can sometimes attract hikers and sightseers.

But looks can be deceiving. The California Invasive Plants Council (Cal-IPC) calls it a moderately invasive plant. If not controlled, then it has the potential to invade natural areas and displace native plants. I know that I've seen it taking over some of my favorite nature areas, such as the Bear Creek Redwoods Preserve. I'm grateful to the staff and volunteers who have kept it in control there.

Controlling Oxalis

When I first moved into my house, Oxalis was everywhere. It was in the front yard, it was in the back yard, and there was a carpet of Oxalis covering one of the side yards. Controlling it can be somewhat difficult. Even though it "does not produce seeds, it is difficult to control because of its ability to form many persistent bulbs". So I got to work weeding, and when I was lucky I pulled out an entire frond, with a bulb attached at the end.

If you don't manage to pull out the bulb, then Oxalis will come back year after year until it is exhausted. Still, it's a relatively easy weed to pull. I just pulled it whenever I saw it coming up each year for around three years, and now I rarely see it in my yard at all.

University of California Agriculture and Natural Resources notes that if wedding isn't effective, herbicides can be used to control Oxalis.