Weeds. They are the bane of a gardener’s existence. While there are non-organic, commercial grade products on the market that are effective, what is a gardener to do if they want to use organic methods? Sure… there is weeding by hand, but that is quite time-consuming. Surely there have to be other options. One product keeps popping in discussion groups. We’ve seen the claims. We’ve heard the stories from friends of friends or a distant cousin twice removed, but yet the question remains. Does vinegar really control weeds?
For most of us, vinegar is readily available at our local grocery store. A quick check of the label states that it contains 5% acidity. But what does that mean? Whether the label lists it or not, the acid in vinegar is acetic acid. It is a colorless, pungent liquid that gives vinegar its distinctive taste. It is also the agent that is the focus of weed control.
In 2002, a press release was issued by the USDA (United States Department of Agriculture). It described weed control using vinegar. For those hoping that the bottle of vinegar in their pantry will do the trick, results indicated that the 5% acetic acid did not produce reliable results.
But this same study showed that for acidity from 10% – 20% was 80% – 100% effective on annual weeds. This same press release stated that vinegar would be useful for killing weeds in sidewalk cracks.
Now you may be wondering why just sidewalk cracks? Wouldn’t vinegar be just as effective on weeds in perennial beds or lawns? While the higher acetic acid solutions were effective on annual weeds, it should be noted that vinegar is ‘non-selective’. This means that the acetic acid does not discern between the broadleaf weeds in your lawn and the grass you lovingly mow.
I decided to try vinegar myself to see how it did. Instead of heading to my grocery store, I went to my local nursery and purchased a 20% acetic acid solution. The label states “A FOOD GRADE ORGANIC ACID For Non-Selective Control of Herbaceous Broadleaf Weeds and Weed Grasses on Residential, Non-Crop, Right-of-Way, and Industrial Land Sites”. The brand that I tested was Weed Pharm by Pharm Solutions. It should be noted that first aid instructions are given on the same label pertaining to 1) in eyes 2) on skin or clothing 3) if swallowed. These alerts imply serious issues so one must handle this product with care.
To truly test this product, I decided to try it on my old nemesis… bindweed. This is a prolific and hard to control weed. In fact, it is considered a noxious weed in many states. It will be the ultimate test compared to a dandelion. For the record, there are few very herbicides that can control bindweed due to its deep taproot. And at no point do studies claim that acetic acid kills bindweed.
As with all chemicals, follow proper application. Apply on a calm day to reduce the likelihood of drift. Also check the forecast to be sure that rain is not expected later in the day because according to Iowa State University, “acetic acid readily breaks down in water”.
With a spray bottle in hand, I liberally sprayed the weeds as directed by Pharm Solutions website. (The area sprayed is within a perennial bed, but I carefully sprayed to avoid the desirable plants). The site also claims that results are seen within six hours. I saw results within three hours. The vibrant green bindweed was turning brown. By the end of the day, very little bright green remained. The following day, I reapplied to the bright green areas of bindweed. Within a few hours, the green diminished. By the end of day four most of the bindweed is completely brown.
For good measure I also sprayed lambsquarter, spurge, knotweed, quack grass, and dandelion. All plants turned brown the same day that I sprayed them. The larger or more vigorous weeds required a second or third spraying. Armed with that success, I also sprayed weeds that were popping up in the sidewalk cracks.
My initial thoughts on a 20% solution of acetic acid? It is an effective organic treatment. The price is also less than non-organic treatments. And for a more economical solution, buy the gallon containers and transfer to a spray bottle for application. Does this mean that I no longer have to weed by hand? Nope. But it does mean that I will spend less time weeding my garden and more time enjoying it.
For annual weeds, such as lambsquarter, spurge, knotweed, quack grass, and dandelion… acetic acid was quite effective. The plants turned brown and actually died. They did not reappear. Success! Annual weeds in sidewalk cracks? Gone. Annual weeds around the edge of the patio? Gone. Annual weeds in the garden beds? Gone.
However, bindweed is a different beast altogether. Even with repeated applications in a single season, bindweed kept coming back. Now granted, bindweed is a very difficult weed to eradicate. Perhaps it will take several years worth of spraying with acetic acid to remove from my garden. But based off of a single season…it did not eliminate this particular weed.
I will still give the 20% acetic acid a thumbs up. It is quite effective on annual weeds. Just be careful of where you spray since it is non-selective (meaning you could accidentally kill something you want to keep in your garden). In my opinion, anything that helps me spend less time weeding and more time enjoying my garden is a good thing.
Great story. Sounds like acetic acid is worth some more research at the least.
So far, I am pleased with the results. I will continue to use it and make notes on its effectiveness. Since I garden organically, I hope to stay with acetic acid.
The weed control recipe I saw with vinegar included epsom salts and dawn dish detergent. Obviously the detergent is a surfactant to spread the liquid on the plant leaf. Do you think the epsom salts causes a “salt the earth” reaction in a higher concentration?
Yes… I remember the dish soap trick from my days as a horticulture student. And I believe that the ‘salt of the earth’ reaction would be correct. So far, I am pleased with the results from the 20% acetic acid solution (though I know that plants with deep taproots will be an ongoing battle). One other thing that I am pleased with is that the acetic acid is cheaper than non-organic herbicides (or at least compared to what is available locally in the nurseries and garden centers).
I have managed to kill plants, my most beautiful hanging basket of petunias, with plain old apple cider vinegar. It’s always a good idea to research these things before trying them. After that I tried it on purpose a couple of times. It burnt the leaves back on burdock but couldn’t kill it off with that deep tap root. Looks like I need to try the stronger stuff.
The thing that surprised me the most was how quickly the leaves began to brown. So far, I have been quite pleased with the results.
Can you share any long-term results with bindweed? We have areas with it we need to control. With hand weeding it just comes back in a week. We have two gallons of this stuff and I hope it works!
What I have seen through using in my own gardens is that the 20% acetic acid works well on more shallow-rooted weeds. If the weed has a long tap root such as bindweed or thistle… the top part of the plant will ‘burn out’, but after about a week, the plant recovers and begins to grow again. Even with repeated applications, bindweed and thistle still manage to recover, but the shallow-rooted weeds are generally controlled with just a couple of sprayings. Examples: mallow, knotweed, spurge, crab grass, etc…
That was kinda my assumption, so thanks for verifying that. It is faster but expensive to spray the bindweed… We will probably stick to the hoe or try something a little stronger.
Thanks for the post!
You are welcome. I had hoped that the 20% acetic acid would work on the bindweed… especially with such promising results in the first few days. But regardless of the number of times we sprayed it on the bindweed… the bindweed kept coming back. By far best results on shallow-rooted weeds.
Grass-choking bindweed is my nemesis also, so it was really interesting to read this (will definitely be trying the vinegar on my sidewalk cracks!). According to the research we’ve done, bindweed is all one plant, so killing it in one area isn’t going to permanently get rid of it. We did find one person who mixed up a plastic coke bottle or something similar of roundup (ugh, I know) and stuck in just a few vines to soak it up, making it so it wasn’t a widespread application, but targeted to just the bindweed. Apparently this DID work – especially in fall when the bindweed is soaking up nutrients to overwinter. I’ve been looking for other solutions though as this wouldn’t be my first choice… 😛 I wonder if replacing the round up with vinegar would work? I’m not sure if the vines would live long enough to soak up enough vinegar, but then I guess you could say that about the roundup too.
Bindweed is the bane of western states. Its deep roots (can be up to 50′) are difficult, if not impossible to remove. With studies I have read, it can take years to eradicate bindweed, but if you are persistent and continue to remove it, it weakens the plant. Roundup tends to be an effective, non-organic method of weed control… but it may take more than one application.
Thank you for this post! Every time I see the 5% vinegar + Salt + Dawn recipe on Pinterest I want to scream that it’s terrible advice! I live in the Salt Lake City area and adding MORE salt to our already highly alkaline soils is very bad. Thanks for debunking that particular recipe while still showing an effective organic solution. The bad recipe was based on a grain of truth but passed through too many who simply don’t know enough about it to give legit advice.
I know what you mean about adding salt to the soil. For us, an organic method of weed control is a priority, but the solution should not be damaging to the soil. The 20% solution is pretty effective and I continue to use it.