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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.

140519-0733In 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!

 

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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.

 

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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.

 

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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?

Read more about buttercup oxalis at Wikipedia.

 

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Did you miss the previous episode in this series? You can also jump back to the beginning.

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December 19, 2012. Morning sun slants across the garden at little yellow house. There was some serious rain, and now thousands of sprouts are popping up in every blank space. The garden is greening up!

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Above: An odd little corner of the front strip features a variety of fascinating plants including petty spurge, groundsel, mallow, cut-leaf geranium, English violets, buttercup oxalis and more, plus a few pretty autumn leaves. Here’s a closer look:

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Right now, our most important task in this garden is thinning out extra sprouts of anything that is too abundant, plus removal of certain plants like buttercup oxalis that we generally prefer to restrict to selected areas because of their invasive nature.

Below: An area shadowed by a purple lantana in the street strip shows a bit of frost on leaves of English violet.

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Above: On the left side of the front walk the daisy bushes enjoy the sun while the wisteria bush behind it is still in shade. It leaves are turning yellow and dropping down. There’s frost on the neighbor’s roof in the background. Under the daisy bushes in front there is a carpet of violets and decorative strawberries, still filling in. Like almost every other plant in this garden they were there to begin with, not deliberately planted.

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Above: Skipping forward to Christmas eve, 2012 the garden continues to grow in rapidly. In the front strip is a drift of blooming buttercup oxalis, pushing up between the frost-burned stems of lantanas. In spite of the frost damage, some stems of lantana still bear pretty purple flowers.

This is one of two areas where we are allowing the oxalis to stay. Here it has to compete with the vigorous lantanas, and it is also quite difficult to extract from this zone without damaging the lantanas. The other oxalis drift is under the big wisteria bush, where they look pretty pushing up through the carpet of fallen leaves.

Below: Closer looks at the buttercup oxalis. The beautiful yellow flowers are edible and excellent in a tart-sweet, tangy way. Try them in salads!

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Below: A few more sweet little scenes from the garden at little yellow house on Christmas eve, 2012. We see English violets, sweet alyssum, a cute mushroom, and some autumn color.

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Next: Wisteria drops its leaves, the owner begins a stone patio, and there’s lots more thinning to do.