Thank you very much for your advice, Habitat Gardener. We will likely do the cardboard mulching, I like the idea of conditioning the soil while smothering the oxalis and not having to remove the smothering cover later. It will probably take us a while to amass the amount of cardboard we'll need for our large area so were thinking to put the weed cover down in the meantime. Or should we skip the immediate covering and let the oxalis have some light so that when we put the cardboard down it may have germinated and started to grow?

How long will the cardboard provide a sufficient cover? If we put it down in January, will it still block the light for the oxalis in March - June?

One last question, if we end up waiting until March to put the cardboard and new soil/compost down can we immediately put a sod lawn on top?

Oxalis comes in a variety of forms.
I have two different varieties growing in my Marin County garden, the large yellow flowering bulbous form and the perennial low tight mat growing form .

I used cardboard to try to eliminate the oxalis the first year I moved into my house.
It worked for a short while, but as soon as I started developing the garden beds it reared its ugly head again.
The only way that I have been able to keep the oxalis at bay is by hand weeding. It is a weekly endeavor that I fear will never cease.

I have not been out to weed the new side yard garden and in less than 3 weeks time that area is almost covered with it.

Destroy it? no (not sure if u really wanna destroy anything alive)

control it? sure can. time spent with a hoe will do amazing things over time.

froggy

Hi GreenElf,

I know that your note is an old one, but I'm hoping that I might be able to talk you out of some of your little pink oxalis bulbs. Would you be interested in trading for something? I'm in zone 8b, Central Texas.

Thanks for answering,
Xtal

Xtal, the weedy types of oxalis here have yellow flowers -- O. corniculatus and O. pes-caprae. No one plants these intentionally.

We also have a lovely native oxalis, O. oregana or redwood sorrel, that has pink flowers and is not invasive. This is probably what you want. It grows in shade.

I do not know if what I am doing is working, but I am digging it out of the ground a little at a time every day. My Oxalis has a central wine colored "carrot" type root beneath the surface, sometimes a couple of inches deep. If you can find that, it is the motherlode. Leaves on tendrils grow out on the surface for many inches and these all have spider roots. You have to dig under the whole area, then separate the grass from the Oxalis you are removing. Then push your grass back down. Certainly you need to get the "carrot" if you can, but if you only remove several inches of the tendrils, I believe you did help some. Keep your pulled weeds in a box to throw away in a bag. Hopefully never to see the light of day again! Removing just the leaves, is of course, worthless. I have only seen a few of the seeds which seem to work like "stickers" which can attach to objects or animals and spread the plague. I have also used "Weed Be Gone" which is expensive and, as far as I can tell, has little or no effect on the "carrot" root which is the plant's genesis. If you just want the leaves and some of the tendrils to die, it works fine. VERY short term and no solution. Good luck. Advice to the unwary, NEVER let Oxalis get a hold. It's an incredible amount of work to eradicate. It will literally take over your yard.

After much searching, I found an herbicide mix called "Monterey Spurge Power". I mixed it at nearly double strength and applied it to a portion of my garden in January. It is now the end of April and the Oxalis pes-caprae has not returned, except for one small plant. It is my intention to use a torch on anything that reappears. I hope this will work.