One of our favorite “trouble plants” is the lovely buttercup oxalis, Oxalis pes-caprae. It is a fascinating little herb originally from South Africa. Above is a patch of lantana that has been completely smothered in a lush carpet of buttercup oxalis.
Yes, it is a noxious invasive that can overwhelm many other kinds of plants. Despite what some gardeners may say (Oh, that stuff never dies. It will be there forever!) it can be tamed, controlled and even completely eliminated. But without the use of icky chemical toxins (please, don’t!) it could take a bit of persistent work.
In South Africa it’s a native surrounded by local herbivores that eat it. Here in California it can spread rapidly through underground runners and bulbs. Many gardeners hate it because it is very difficult to remove. Directly pulling up the plant almost always leaves the bulbs behind, which can be as deep as six inches or more. Yikes!
it can be done!
The good news is: They can be cleared by persistent, complete plucking of all new rosettes every few weeks during the winter growing season.
But you really will have to keep after them! Do not allow any rosettes to get to the blooming stage because that is when they send out dozens of tiny underground bulblets. Each bloomer will be surrounded by a six-inch radius of tiny new plants next spring. You must pull out all rosettes, no matter how tiny.
It is enough to pluck out the stems if you are patient and persistent, but the biggest ones can come back four or five times before they give up. Fortunately, we can move faster. Just keep plucking.
You can eliminate them faster if you get the bulbs. Use a long, thin, sharp tool like a weeder, screwdriver, or thin trowel to shove down deep under each rosette. Your goal is to break open the soil without breaking the lowest stem of the plant. It can be tricky, especially if your soil is dense, but there is a certain joy in gently shaking off loosened soil to find a bulb clinging to the thin thread at the bottom of the root. That one will not come back!
you can eat all of it
Not everything about buttercup oxalis is bad. Not only is it exceptionally pretty, it is also edible. The sweet-sour yellow flowers and flower stalks are great in salads, and the bulbs are said to be good for getting rid of tapeworms. I haven’t had a chance to test that claim yet.
As invasive as they are, we love these little plants. But we keep them in their place. Where is that? Several places, actually.
a drift in the leaves
Natives-only gardeners may cringe, but there can be a place for these little beauties in a deep nature garden. There may be a spot in the semi-shade with deep leaf debris, where buttercup oxalis can poke up through the leaves. The best place for such an oxalis drift is under a deciduous bush or tree, so that they can enjoy some filtered sun during the winter growing season. The annual leaf drop from above can challenge them and help to keep them under control.
In the picture above there are lemon-yellow buttercup oxalis flowers under the blooming wisteria vine, and spilling out into a sunny meadow of california poppy, wild strawberry, and English violet.
If you want a big harvest of the sweet-tangy flowers you can create a more robust and productive drift of oxalis. Just let the little cuties grow in some likely place. In the picture below is such a drift among some beautiful rocks. If it is strictly removed from other garden areas it can be a gorgeous and tame part of the ecosystem. But it will definitely need to be controlled around the edges.
tame, beautiful, delicious
The best place of all for a wonderful, edible little invader like buttercup oxalis is a container. As you might imagine, they are fairly easy to grow. We’ve been growing some in our eco-packs. Want one?