Weed killer made from vinegar and salt #233149

Asked March 26, 2015, 10:14 PM EDT

Hello, I have a patch of ground next to my garage that I want to kill all the weeds & vegetation. I remember hearing about a homemade weed killer made from vinegar and salt but there are too many recipes on the internet with questionable validity. I trust OSU and would like you to weigh in on the issue. With my thanks! Jim

Coos County Oregon

Expert Response

Hi Jim,

Vinegar and salt (alone or in combo) as an herbicide will not generally be effective at weed control.  The concentration of acetic acid in over the counter vinegars is too low (5%) to give you effective weed control.  Acetic acid needs to be between 15%-20% to give reliable weed control.  You need a pesticide applicator's license to purchase and use these very caustic herbicides, because at such a strong concentration ~ you can burn your skin or the cornea in your eyes.

Homemade vinegar herbicides (5% acetic acid) **may** give you decent control on small annual weeds (e.g. lambsquarters, chickweed, groundsel) ~ but will probably not give you control if these annuals have grown to a larger size.  Homemade vinegar herbicides will not control perennial weeds (e.g. dandelions, bittersweet nightshade, bindweed, thistles).  You may get 'top-burn', but the extensive root systems of perennials will just allow these plants to come right back.

Salt as herbicides may harm weedy plants ~ but it's not a best practice because of negative impacts of salt addition on soil integrity.  Salt degrades soil integrity and impedes water movement through the soil.  So, I wouldn't recommend salt.

Boiling water is also often recommended as a homemade herbicide.  Once again, you may get control of small annuals, but not larger annuals or perennials.

If you want to clear an entire patch of vegetation, mechanical removal (probably, coupled with a broad spectrum herbicide) is likely to be most effective.  You may be able to get control by mechanical removal, alone . . . but you'll probably have to repeat the process several times ~ potentially also coupling this approach with mulches or groundcovers.

For broad spectrum herbicides, you want to look for products with the active ingredient of glyphospate.

This probably isn't what you wanted to hear, because it sounds like you're trying to avoid using commercial herbicides. But ~ part of the reason they're so popular is because they are effective.

Good luck! 

Gail Langellotto Replied March 27, 2015, 6:02 PM EDT

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