Vinegar Weed Killer – My Experieince

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Robert Pavlis

A while ago I wrote about using vinegar as a weed killer, in Vinegar Weed Killer Myth and reported on the scientific evidence for vinegar weed killer. It does not kill larger weeds with established roots, but can have an effect on seedlings. Vinegar is recommended so much in social media that I decided to give it a try myself.

I ran a few simple experiments to see how effective vinegar is for killing weeds.

bottle of vinegar
Homemade Weed Killer: Vinegar

Vinegar Weed Killer

In this post vinegar refers to the stuff you can buy in a grocery store. I decided to use pickling vinegar with a 7% acetic acid concentration. Around here it is the same price as the 5% strength, so you might as well buy 7%. Besides it might work better.

This post does not discuss 20% acetic acid which is a dangerous chemical that does kill some weeds.

Homemade Weed Killer: Vinegar

So vinegar kills some weed seedlings, but mostly it just burns off the green parts above ground. I was curious to see how effective it is. It might be a worthwhile product to use on a patio where a lot of the weeds are seedlings.

I just happened to have some weeds in my patio. OK, I always have weeds in my patio, but I have a garden open house in two weeks and need to remove them to make people think that I am always weed free.

Soil Science for Gardeners book by Robert Pavlis

Before Pictures:

small weeds in the crack of patio stones
Small patio weeds before being treated with homemade weed killer, vinegar, June 22
large weeds in the crack of patio stones
Large patio weeds (goldenrod) before being treated with homemade weed killer, vinegar, June 22

People claim that the weeds “die within hours” of being sprayed. After a few hours I saw some browning, but not very much. I decided to wait until the next day before taking the following pictures.

24 Hours Later

small weeds are all brown
Small weeds after being sprayed with pickling vinegar, June 23

The weeds in the sprayed area do look quite dead. The green ones in the top and upper right corner of the picture were not sprayed.

large weeds are still green
Large weeds, 24 hrs after being sprayed with pickling vinegar, June 23

You can see that some of the smaller weeds have brown leaves, but the larger weeds seem to be unaffected. So I gave them a second good soaking.

After Second Spraying

large weeds are mostly brown but some green still shows
Large weeds, several days after being sprayed with pickling vinegar for a second time – still not dead, July 3

The vinegar did not do a good job on the large weeds. Even after several days, they had some green leaves. I ended up removing them by hand before the open house just to clean things up.

Eight Weeks Later

small weeds are gone but a large crabgrass plant is now growing
Vinegar seems to have killed off the small weeds, August 16

It is now mid August, and the above picture shows the area where the small weeds were sprayed. They did not regrow. The one large weed is a crabgrass that has recently grown from seed. I have to admit, it was more effective than I expected. I can understand why people claim vinegar kills weeds.

Vinegar vs Crabgrass

The above experiment showed that vinegar does kill small seedlings. By mid August the spaces between my flag stone pathway was full of crabgrass. I wondered if vinegar could be effective against crabgrass?

I used the same pickling vinegar as in the above experiment, and sprayed the pathways.

Before Pictures:

lots of crab grass
Crabgrass growing between flag stones, before being sprayed with vinegar
lots of crab grass
Closeup of Crabgrass, before being sprayed with vinegar

Not all of the weeds in the pictures are crabgrass, but many of them are.

After Pictures (24 hours after being sprayed with pickling vinegar):

crab grass is still there, but looks brown
Crabgrass growing between flag stones, 24 hrs after being sprayed with vinegar
closeup view, crab grass is still there, but looks brown
Closeup of Crabgrass, 24 hours after being sprayed with vinegar

The plant leaves are certainly brown, and to the untrained eye – they look dead. The green weeds in the upper left corner of the closeup view are weeds that did not get sprayed.

If you get real close to the weeds, as in this next picture, you will see that the crown of the plant and the stems are still green. For the most part, only the flat blades of the leaves were damaged by the vinegar, and then only the ones that got into direct contact with the vinegar.

closeup of one plant showing quite a bit of green
Crabgrass weed showing that most of it is still green 24 hours after being sprayed with vinegar.

A week later, and the weeds were growing back with new leaves. They were not killed by the vinegar.

 Vinegar is a Contact Herbicide

The above pictures show that the vinegar only affects the parts of the plant it contacts. That is consistent with the scientifically reported mechanism for vinegar. It affects the cell membranes of a plant, causing rapid breakdown/desiccation of foliage tissue on contact. It is a contact herbicide only damaging the green parts it contacts. The rest of the plant, and especially the roots are unaffected by the vinegar. This explains why it is not a very good herbicide for larger plants.

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Robert Pavlis

I have been gardening my whole life and have a science background. Besides writing and speaking about gardening, I own and operate a 6 acre private garden called Aspen Grove Gardens which now has over 3,000 perennials, grasses, shrubs and trees. Yes--I am a plantaholic!

35 thoughts on “Vinegar Weed Killer – My Experieince”

  1. I want to tell everyone that this, indeed, is just a myth. I’ve tried and tested it all, and as stated here – it’s just based on a myth. It’s nothing more than that, trust me.

    Reply
  2. I have used vinegar full strength several times over a six year period to knock back the vegetation thriving between the pavers of my daughter’s 10′ by 24′ patio. I fully saturated the above ground portion of the plants because the restrained attempt on my first skirmish was hugely ineffective. Anything over a foot tall would be trimmed to that length as I noticed that the weed would rebound more quickly if it were merely decapitated. Application on the first of several hot sunny days was the ideal – a cloudy, cooler, or rainy following day diminished the killoff.
    I initially used a small hand sprayer but it forced me to bend down to their level and was very time consuming. Also it seemed wasteful with the overspray. Three years ago I changed to an old plastic bristled broom which was intended for sweeping the patio and dumped the vinegar into a plastic pail wide enough for the broom head. The vinegar was then painted onto everything green. The job was finished in five minutes instead of twenty, and that less vinegar was used was the big surprise. The still wet broom was used to clean the sand pushed up at a couple of ant tunnels. A next day inspection showed this application to be at least as effective as spraying the weeds, with a bonus of a much diminished activity of ants.
    Of course this is only maintenance, not eradication of either weed or ant which would be undesirable.
    Regular, pickling, and cleaning vinegar – I have used each several times and have not detected any benefit in the higher concentrations so now I use the lowest cost per volume (usually but not always the regular). I think the application method is the significant variable. Results with the broom have been more consistent, probably because it is easier on my back and I am likely more thorough.
    No census on the weed population was polled but usual suspects were present – dandelion, goldenrod, thistle among many unidentified. I find it harder to enjoy the process if I know the plants names.
    Finally, I had switched to vinegar after exhausting a meager supply of Roundup on site the first couple of times. They were equally effective with the cost benefit favouring vinegar.
    And salt. The patio abuts a municipal sidewalk which in turn abuts a paved roadway in a northern Ontario community. Each spring when the snow vanishes all three are whitewashed with salt until enough rains rinse them clean. Immediately the weeds begin.

    Reply
  3. My money is on Bob Webster and Howard Garrett, the Dirt Doctor. Ive used their formula (adding orange oil) for years. I buy 9% acetic vinegar. Dont dilute. 20% bit too pricey. It works. 2 of the most knowledgeable guys you can find on organic gardening!

    Reply
  4. I agree, it is a contact herbicide, and although the salt can inhibit root growth in the long run it will take multiple applications. Likewise holds true for the systemic glycophosphate brands like roundup contributing to algae blooms in lakes in Florida which the majority of are now just giant wastewater retention ponds creeping into our water supply. If you are diligent with application of safe practice of contact herbicide, after a few applications the roots begin to retard and die with most weeds. Because without the top plant feeding them, the roots too eventually die. I’ve also noticed where they spayed heavy roundup for road maintenance return again full flush in 3 months time. I’ll stick with this remedy anyday. Better Homes and Gardens has a myth article on it the natural remedy too, but they also run Monsanto ads for Roundup. Who you gonna call? Weedbusters and Myth busters.

    Reply
    • If the roadsides regrow it is because (a) they either did not apply the Roundup correctly, or (b) it is new weed seeds that sprouted.

      Reply

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