Which Products Do I Need to Kill Oxalis Weeds?
Getting Rid of Oxalis on Your Lawn with Selective Post-Emergents
To treat oxalis or wood sorrel weeds among desirable grasses, choose a selective post-emergent herbicide that is labeled for oxalis/woodsorrel and follow the instructions regarding when and how to apply. Since oxalis grows mostly in the summer, that's when you should keep an eye out for the distinctive five-petaled flowers to spot new weed growth on your property.
Look for a product containing the active ingredient atrazine or a combination of dicamba and 2,4-D. These ingredients are known to work well against oxalis weeds in grassy areas. Not every product works with every turf type, however. Confirm that the product you are considering is labeled for use on your type of grass before purchase.
Oxalis weeds often leave seed pods behind underground, and this can mean that more stalks appear in a treated area. Don't give up--repeated treatments with your chosen herbicide may be required to eliminate this persistent weed. These seeds will most often germinate and sprout in the late winter to early spring, resulting in the summer growth mentioned above. Some remaining seeds can germinate at any time of year in the right conditions, however.
Options for Treating Woodsorrel in Landscaped Areas
If oxalis is present in landscaped areas, they can be treated with a non-selective herbicide that contains glyphosate. Try to treat the oxalis weeds while they're still seedlings--before they've grown flowers. This type of non-selective product will cause injury to other plants around the oxalis, so these applications are not suitable for most lawn or turf areas.
Oxalis weeds are able to spread by several different methods including the growth of horizontal roots called rhizomes. Even a severed fragment of these roots can result in new oxalis growth nearby. Because of the difficulty of manually eliminating every trace of these weeds in your landscaped area, using one of the recommended products below is the most effective way to fight oxalis or wood sorrel in landscaped beds and around ornamentals.
Getting Ahead of Future Oxalis Growth with a Pre-Emergent
To prevent any remaining oxalis seeds in your soil from germinating and bringing more unwanted weeds, apply a pre-emergent weed preventer in the fall before the first frost hits. Pre-emergent herbicides that include the active ingredients Prodiamine and Isoxaben are good options for preventing Oxalis seed germination.