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.