If you have ever tried household vinegar as a weed killer only to find the weed eventually grows back, this explains why. Commonly suggested as a “chemical-free”, “natural” alternative to commercial herbicides, there are reasons why it should be used with caution.
If you are interested in misleading gardening advice, these garden myths have been causing trouble for years.
Is Vinegar Really a Harmless and Effective Herbicide?
The Problem With Vinegar For Weeds
White vinegar and other household vinegars are under 10% acid. When applied to plants, they may burn the foliage but most roots survive and the plant regrows.
Horticultural vinegar is approximately 20% acid, highly corrosive, burns everything it touches, and not suitable for household use.
All vinegars are deadly for any wildlife they touch including invertebrates and garden critters like frogs, salamanders, and worms.
Check any online gardening forum and as soon as someone asks for a way to kill those weeds on their brick patio, someone always recommends household vinegar.
“Just spray it on and the weeds die,” they claim. Or, “they die for a while and then grow back. But at least it’s natural!”
The implication is, that vinegar is a smart, safe, and “natural” choice. And, if it’s in our kitchens, it must be okay for the garden, right?
But is this good advice?
What is vinegar? Does it kill weeds? And is it really harmless?
What Vinegar Does to Plants
What is vinegar?
Vinegar is acetic acid, made by fermenting ethanol or sugars.
There are different concentrations, depending on the type of vinegar.
The vinegar you have in your kitchen will probably say “5% acidity” on the label.
Some brands also sell a “cleaning vinegar” which is 6% acid.
Pickling vinegar can get you up to 7%, and that’s probably the highest concentration that you might have at home.
Horticultural vinegars are highly corrosive and not suitable for home applications.
As you’ll see, it is not a sure bet—and can do some other harm.
Vinegar (acetic acid) is a non-selective burndown herbicide. In other words, it burns plants.
Just like an acid would burn your skin, it destroys cell membranes.
And not just weeds, but any plant or living thing it touches.
But, depending on the concentration and the weed itself, this does not mean it kills the whole plant.
Vinegar can only burn the parts it touches and unless it gets right down where the roots are, it is not going to kill the plant, which is what we want.
Yes, in some instances it may reach the roots and burns them—particularly if the plant has shallow roots, but, more commonly, it just affects the foliage above ground level.
Meanwhile, the roots are still there and the stems and leaves grow back.
Plus, those other living things in its path—like frogs or toads—may be burned in the process.
Spraying Household Vinegar on Weeds
Vinegar burns the plant parts it comes in direct contact with.
In contrast, selective herbicides (various commercial products made for killing weeds) are designed to be absorbed by the plant, spread to the root systems, or disrupt some other systemic function, which kills it off.
This is not a recommendation for any type of weed killer: the selective ones bring a whole other set of problems. I’m simply explaining the difference between those and vinegar.
Vinegar can burn and kill very small weeds, but household vinegar is unlikely to kill larger ones.
Tiny, tender seedlings with shallow roots don’t stand a chance, but those larger weeds like crabgrass that sit proudly in the cracks of our brick patios with roots deep in the ground are not giving up so easy.
Gardeners are sometimes fooled because, after spraying vinegar, they notice the leaves dying back and assume the entire plant is dying, but often it’s just leaf burn and the roots are still alive. The plant is temporarily knocked back but it will return with a vengeance.
Related: 7 Weeding Tips Every Gardener Should Know
To be an effective herbicide, you need a 15 to 25% concentration of acetic acid. This is sold as horticultural vinegar, but this is not the vinegar you’ve come to know from your fish and chips.
Horticultural vinegar is dangerous stuff and not suitable for home use. It is a highly corrosive acid, and absolutely not worth the risk of burning yourself or causing damage.
But, will it burn weeds?
Yes: it will burn anything it comes into contact with. But we started this whole conversation because we want harmless, chemical-free* ways to deal with weeds, and this does not check any of those boxes.
*I’m using ‘chemical-free’ the way it’s used in garden forums (implying toxicity) not science since obviously everything in our world is comprised of chemicals.
Household vinegar is a chemical (acetic acid) and not ‘natural’ or harmless.
It is non-selective, meaning it burns everything it comes into contact with: plants (perennial or annual, weeds or not), and living things from animals to microorganisms in the soil. It immediately burns the skin of amphibians like frogs, toads, salamanders, and reptiles including snakes and turtles.
And this does not make it a good weed killer.
Small weeds with shallow roots may be killed. Or not.
Most large or deep-rooted weeds will likely just get their foliage burned and gradually grow back.
Horticultural vinegar is too dangerous for use at home, and neither natural or harmless.
But it worked for me!
If the vinegar got the roots, then yes, you scored root death.
Most likely, though, unless the roots were destroyed, the plant will rebound in the weeks or months to come so you can do this all over again.
Other Non-Toxic Weed Removal Options
There is this curious assumption in the gardening world that there must be a solution for every problem. And sometimes it comes with a tone of entitlement, as if we should be able to control nature exactly to our liking, no matter what overall effects ensue.
But if you wish to grow a garden without doing more harm, this just is not so.
Sometimes we have to accept problems—and most are temporary anyways—or accept less than perfect solutions.
Hand weeding is much easier when done after a good rain that loosens the plant roots. You can read all my top weeding tips here.
Invasive species require research to learn recommended removal methods.
For weeding a brick driveway, sidewalk, gravel, or stone pathway, I have found something that seems to work quite nicely without having to hand-pull the weeds for hours.
I use my home steam cleaning machine to kill the weeds on our driveway. It’s much easier than taking out pots of boiling water because one session provides 30-45 minutes of steam, and I can work standing up.
I was skeptical, but it really does get down to the roots, even with the crabgrass. If you go to the article you can see a video of how it works.
Keep in mind though that just like vinegar, boiling or steaming water is going to kill tiny living things it touches, so I would not do this anywhere but on a brick pathway, free of any animals including pets.
If you do manage to truly kill off or remove the weeds (roots and all), consider adding polymeric jointing sand to the cracks to prevent new seeds from germinating there.
If you are wondering about other popular garden advice, click here for more on household items like dish soap, Epsom salt, eggshells, coffee grounds, and more. The concern is not just if they work but at what environmental cost.
ListenNEW! Click play to listen:
- Find out why dandelions are misunderstood both by fans and foes.
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- Popular Garden Myths
- The Epsom Salt Myth
- Why Dish Soap is Not Good in Gardens
Keep safe out there and be kind to our earth,
~Melissa the Empress of Dirt ♛
Kitchen Propagation Handbook
7 Fruits & Vegetables To Regrow As Houseplants
by Melissa J. Will
Learn how to grow houseplants from avocado, oranges, lemons, ginger, and more using leftover pits, seeds, and roots.
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