How To Use White Vinegar as a Weed Killer

Last week I received a note from Dwight in Bethlehem, PA, about how he made a weed killer made from white vinegar.

“Todd,
I have stone landscaping instead of mulch and have a few weeds coming through the weed tarp to say the least. It looked great the first full year after finishing the job, but soon after, the weeds took root. This year is a fast bloomer for the weeds in my landscaping. I just wanted to let you know that I tried using boiling hot white vinegar as a natural weed killer, and it worked great. Being careful not to hit anything but weeds, everything that I sprayed was totally dead and discolored less than 24 hours later. Getting the boiling hot white vinegar to come out of the sprayer was a challenge, but the result was better than expected. Now if I can only find out where to buy a case of vinegar, I’ll be set. It took me 2 gallons and I didn’t even get around half the house, but I am hoping that this is a more permanent weed control than what I’ve had in the past.“

Should you use household white vinegar or horticultural white vinegar to kill weeds?

White vinegar is an ages-old solution for organic weed control. Household white vinegar – the kind you buy at the grocery store – is a 5% concentration and is effective in killing some species of weeds. (see the USDA research here). There are various concentrations of white vinegar and the higher the concentration, the more acidic it is. Horticultural white vinegar is 30% concentration, which means it’s many times more acidic than household white vinegar. It’s not necessary to use the horticultural variety to kill weeds, but if you opt for it, please handle it very, very carefully, with gloves and safety glasses.

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How is white vinegar made? Is it okay for organic gardening?

Vinegar is approved for weed control in organic gardening and organic farming. Chemically, any vinegar is a combination of acetic acid and water, made by a two-step fermentation process. It’s typically derived from a plant food such as potatoes, rice, fruits or grains. In the case of white vinegar, it’s distilled from fermented grains into a solution of nearly pure acetic acid in water.

How to use white vinegar as a weed killer

Vinegar is a lot cheaper than weed killers like Roundup and doesn’t expose you to cancer-causing chemicals. No special recipe is needed to kill weeds with vinegar, such as using dish soap and salt – vinegar will get the weed killing job done all on its own.

But be careful with your application because vinegar is highly acidic and non-specific – most plants you spray it on, from grass to ornamentals, will die (especially with horticultural vinegar). It may also lower the pH of your soil in that spot for a few weeks.

Never use white vinegar on weeds around the fruits and vegetables in your garden – a sudden soil pH spike near those plants may kill them or at least affect their performance. And if you accidentally spray the vinegar on the foliage of your vegetables or fruit, they may be done for the season. Always weed a vegetable garden by hand and use mulch and companion planting to suppress weeds.

Do not use white vinegar if you need to weed a large area where you wish to plant grass, vegetables, or ornamental plants – it’s highly caustic and may acidify your soil for longer than you’re prepared to wait.

Sometimes, all you need is boiling water with salt to kill weeds

I’ve found that simply adding salt to boiling water is sufficient to kill most weeds. Whenever I see a weed growing between cracks in the sidewalk, I take my tea kettle outside at full boil, pour it on the unwanted weeds and it cooks them almost immediately. But the white vinegar solution is great for larger, more stubborn weeds.