Question from Charlie:
I am trying to identify a small bulb that I thought was cute when it first arrived in the soil of another plant. Now I think it is a weed – very prolific. I suspect it is in the oxalis family: 3 lobed leaf, red stem, pretty pink flower that is petunia-like & about 3″ tall, but lays on the ground. It has taken over my garden & I’m trying to dig it out. It starts as a seed & becomes a bulb. Can you confirm my suspicions? Any suggestions on getting rid of this plant? (I looked under oxalis in my Western Garden Book & didn’t find any that matched my plant.) Will Roundup kill it?
Answer from Pat:
The small, winter-blooming, pink flower with yellow eye, and three-lobed, grayish-green foliage is Oxalis purpurea ‘Cherry’, a selection of a South African corm. This dwarf, ground-hugging variety you have is somewhat rare. However, the surprising fact is that I have it in my garden also where it is often admired and where I cherish it myself. There are many other named cultivars of this species of oxalis but you have one of the rarer types. I’m surprised you don’t like it, but I imagine the difference is how it is being used and whether it gets inadvertently moved around. I have it growing on the edge of a raised bed that is walled with un-mortared stone. For the most part it stays close to the rocks and graces one side of a path. In this area, it’s neat and tidy looking. The foliage springs up with the first rain and is soon dotted with flowers that bloom in a cheerful shade of deep pink all winter long. As soon as hot weather returns it dies to the ground and is not seen again until fall. The color of the flowers looks particularly good inside each individual plant’s rosette of soft gray-green foliage. So far as I can tell this oxalis has no pests nor diseases. Caterpillars, slugs and snails all shun it.
You mention the fact that for you it is invasive. If one digs up the ground in the area where it is growing one might spread the corms. That has happened in my garden and a few of these plants are now growing in a wildflower bed in my garden, but they are as welcome there as they were in the other location. I don’t think this plant makes seeds, and in my garden it stayed in one place for many years and actually took many years before I had enough of them to share with my friends who wanted some. Maybe you are being too good to it?
If you really want to kill this oxalis I suppose Roundup would do the job, but I am not sure, since the corm might continue to live—corms tend to be persistent—, and anyway, as an organic gardener I don’t believe in Roundup. If you used Roundup you will find that seeds will not germinate well for several years in that area. Here are three ways for getting rid of it: One: You might be able to ask your local garden club to come and dig these plants up and pot them for one of their garden sales since it’s much admired by many gardeners and difficult to find. Two: I would think that the best way to get rid of this plant would be too dig them up during growth and bloom and sieve the soil, throwing away the corms. Start digging them up in fall and continue until spring, getting rid of the plants each time a new one sprouts. Three: Shade kills this plant. Cover the ground with a thick layer of mulch and you will not have it any more. I think the reason my little patch of this oxalis never spread is because I habitually mulch the ground. The only place it could survive was in the earth-filled crevasses of a dry wall.
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