Don't know if you are opposed to chemicals, but I recall in my Master Gardener course that the only way to get decent results with killing Oxalis is to repeatedly spray them with Roundup. The key is to spray them BEFORE they flower. Apparently when they flower, they also make those baby bulbs, and the Roundup won't get all the babies. I rarely use chemicals in my garden, but Oxalis is one plant that requires it IMHO.

I tried baking soda mixed with dish soap and water in a sprayer and sprayed one patch in my yard really well (recipe is all over the web if you google the appropriate words). That patch of Oxalis is dead - they died really dramatically - all wilted and discolored etc overnight. I have not yet sprayed the rest of the back yard with this concoction because I am not sure if the Sodium from baking soda will make the earth unsuitable for vegetation.
About the vinegar, you might want to repeat the application more than once in one spot to see any result.
I am trying to smother the Oxalis in some sections with cardboard and mulch on top.
So, far, I am keeping away from Roudup and Ortho as i do not wish to use chemicals. But, as you said, it is getting ridiculous in my yard too - they are even taking over my potted plants.
If someone found a way to eradicate Oxalis without using herbicides, they will become millionaires for sure.
Good luck, it is not an easy fight.
PS: you might want to post this question in the weeds forums too.

Forgot to add, I have come across articles on the web about a product called "Oxalis X" which is made from liquid Ammonium Thiosulfate which is guaranteed to kill Oxalis. I think the manufacturer is "Pro-Gard". I have not yet found a seller of this product.

Today, i got my hands on "Oxalis X" - after calling the manufacturer and their distributor, I was told that the last person to order the product from them was the local ACE Hardware store in my area - sure enough, they had it. I hope this information is useful to you.

Thanks everyone!
Isn't that baking soda mix the same as the one you spray for mildew on plants? The amounts must be different. Good to know though.
ashleysf it would be great if you could post after using and let us know. I will go pick up some too and we can compare.
Yeah they are ending up in my pots too. The "rampage" started after I started using OSH brand potting mix. It contains mulch....I am thinking it is mulch where the oxalis is still alive or something. Because that is what I use in my pots and sure enough...they are there too.

Unless it is an evil snail plot and they carry it along with them! (Joking).

Thanks again,
Sandy

If you have pots over earth where Oxalis pes-capre is growing, the shoots will grow into the pots, and they form bulbils along the stems which start new plants, The bulbils form prolifically if the plants are unmolested, and are so small and do not pull up when pulling the stems, so they are nearly impossible to remove completely. I think the bulbs also manage to pull themselves down deeper into the soil as they mature, so this plant is extremely well adapted to the various rodents that like to eat it back home in South Africa, where it is actually rather rare.

bahia, that is so interesting. How come the rodents here don't want to touch them ???

In my yard the gophers make cache's of these bulbs (0xalis pes-capre) in underground chambers. Since I am actively trapping them, a lot of these cache's remain until Fall when there is a massive eruption of growth stems...

I have dug up several of these (2-3 a year) and found hundreds of bulbs. Once there were also bulbs of Crocosmia and Schizanthus as well.

I wouldn't be so quick to think that the massive eruptions of Oxalis are due to caches by gophers. The way this plant forms little bulbils at the base of the stem and sends out rootlets that form new bulbs will also result in thick clusters of the bulbs where they are left undisturbed. I have never seen any signs of gophers going after these here in the Oakland/Berkeley area, and the oxalis crystals that would build up in anything eating large quantities of these would tend to discourage consumption. I think the rodents which do eat them in South Africa, (but are not gophers), have developed immunity, so do actively seek them out.

Well I would....
Don't be a doubter, the bulbs are found in a chamber which is lined with grass and leaves, and all the bulbs are full sized, not the small offsets.

Not living underground, or wanting to dissect any gophers, I can not verify they actually eat them, perhaps they just like to collect them.

That would be ironic, gophers collecting tubers...I dunno I find it funny.
I found one about 2' underground - a tuber, not a gopher - and it was huge! Like 5" long. I knew my battle was lost at that point with the digging.
I actually like oxalis, just not everywhere. They are a pain, literally, to get out of my cactus pots.
I live in a "no sell" zone for Oxalis X. Ace can't order it for San Jose for some reason...at least where I live. Probably the water table and the streams...who knows?
Thanks for all of the useful information and the conversation though.
I think seed savers sells an oxalis relative that grows giant tubers for eating. I actually looked at it then I came to my senses.
Sandy

Sandy, I am also from San Jose. The ACE that i got my Oxalis X is the one in East Bay called Dale Hardware. They have them in stock or can order bigger sizes of it if you need it. I called around and only this ACE had it in stock and the garden department people there seemed to know what I was talking about.
there was a specialist at Yamagami's nursery in San Jose who said that they can order it for me, but I might have to buy the whole case from them and probably share it with someone else. So, it is possible to order it in san jose.
Oxalis X is certified for sale in all of California. Dale Hardware tel # is 510-797-3700. And here is their website:

Here is a link that might be useful: Dale Hardware ACE in Fremont

OSH used to carry some of the Oxalis specific weed killer (I am pretty sure it was Oxalis X).
FWIW I tried it on the oxalis pes caprae and it was not effective.

Does anyone have the contact information for the company (possibly Pro-Gard) that manufactures "Oxalis X"???