GardenCalc
The Short Answer
Mix 1 litre of white vinegar (5% acetic acid) with 1 tablespoon of washing-up liquid in a spray bottle, then spray weed leaves until wet on a dry, sunny day. It burns off the top growth of annual weeds like chickweed, but that is all it does. It will not reach the roots of perennial weeds like dandelions or bindweed, and the RHS advises against using household products as weedkillers at all. The rest of this page covers the exact method, the legal position in the UK, and what to do instead if you want a result that actually lasts.
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The Vinegar Weed Killer Recipe, Step by Step
This is the recipe most UK gardeners mean when they say "vinegar weed killer": ordinary white vinegar from the kitchen cupboard, plus a squirt of washing-up liquid to help it stick to the leaf.
Vinegar and Washing-Up Liquid Spray
You Need
- 1 litre white vinegar (at least 5% acetic acid, standard supermarket own-brand is fine)
- 1 tablespoon washing-up liquid (any brand)
- Spray bottle
- Pour the vinegar into the spray bottle.
- Add the washing-up liquid. Swirl gently to mix, do not shake vigorously.
- Spray directly onto weed leaves until dripping wet. Avoid spraying plants you want to keep, the spray does not know the difference between a weed and a prized perennial.
- Apply on a dry, sunny day. Rain soon after spraying washes it off the leaf before it has done anything.
- The sprayed leaves brown off. Perennials regrow from the roots, so expect to reapply as regrowth appears, or dig the roots out.
This is a contact herbicide, which means it only kills what it physically touches. Cover the leaves fully, but do not soak the surrounding soil more than necessary.
Does It Actually Kill the Roots? What RHS Says
Vinegar (acetic acid) burns and dries out the leaf tissue it touches, which is why sprayed weeds turn brown. What it does not do is travel down into the root system. For annual weeds like chickweed, that is enough, the whole plant lives and dies within one growing season, so killing the visible growth usually kills the plant for good.
For perennial weeds with spreading root systems, it is a different story. The RHS is direct about this. On bindweed, they say vinegar "is sometimes recommended, but this is not an effective control method", and they give the same verdict, word for word, for ground elder. Both are perennial weeds that regrow from roots left in the soil, and a spray that only reaches the leaves will not touch what is happening underground. Expect regrowth, and be ready to reapply repeatedly or dig the roots out directly.
More broadly, the RHS's position is that "it is not advisable to use household products, such as bleach, vinegar or washing-up liquid, as pesticides". Their warning is that homemade mixes often cause real damage below the surface, not just to the weed you sprayed but to the soil life underneath it. We have included this recipe on the page because people are searching for the exact ratio and deserve a straight answer, not because we are recommending vinegar as your primary weed control method. For non-chemical options and four more recipes rated for effectiveness, see our full natural weed killer comparison.
The Vinegar, Salt and Washing-Up Liquid Ratio, and Why We Don't Recommend the Salt
The other recipe that comes up constantly is the "triple mix": vinegar, salt and washing-up liquid together. The commonly shared ratio is 1 litre vinegar to roughly 2 to 3 tablespoons of salt to 1 tablespoon of washing-up liquid.
The triple mix does kill weeds effectively, salt is genuinely toxic to plants. But unlike vinegar, salt does not break down. Our own view, from what we have seen in gardens rather than from a lab, is that it hangs about in the soil long after the weeds have gone and washes sideways into beds you did care about. If there is any chance you will want to grow something in that spot again, or the area drains toward beds you care about, skip the salt entirely. Vinegar and washing-up liquid alone (the recipe above) does the same job on annual weeds without the soil damage.
For the fuller breakdown of five weed killer recipes rated for effectiveness, including horticultural vinegar and salt water on their own, see the natural weed killer comparison.
Is It Legal to Use Vinegar as a Weed Killer in the UK?
The honest answer is: not clearly, and the regulator will not tell you it is. Weed killers are "plant protection products" in law, and HSE's guidance for home gardeners says products used to control weeds "must be authorised or permitted before they can be marketed or used in the UK". Kitchen vinegar is not an authorised weed killer. HSE knows gardeners use home-made remedies and its own words on that are careful: some, like beer traps and coffee grounds, fall outside the rules, but that "does not mean that use of these remedies including use of common household chemicals as a PPP is without risk or that it is always legal". It also says that if a home-made remedy is passed on to somebody else, free or not, that "may fall in scope of the regulations", and that where HSE finds evidence of "such a supply or use" it would consider "appropriate and proportionate enforcement action". So we are not going to tell you that spraying kitchen vinegar on your path is fine in law, because HSE does not.
The RHS position is plainer still: it "is not advisable to use household products, such as bleach, vinegar or washing-up liquid, as pesticides", because home mixes often wreck the soil life underneath as well as the plant you sprayed. Our line, if you want a spray that is on the right side of the rules: use a weed killer that appears on HSE's garden database and follow its label, or skip chemicals altogether and hoe, hand-pull, mulch or use boiling water.
One thing worth knowing about "vinegar" here. Acetic acid, the active ingredient in vinegar, is an approved active substance under Regulation (EC) No 1107/2009 as retained in UK law. That approval attaches to a specific, registered, labelled horticultural vinegar product sold as a weedkiller, not to a bottle from the kitchen cupboard. If you buy a "weedkiller" branded vinegar product online, check it against the garden database before you use it. HSE's advice is that a product not listed there is probably not authorised, and it warns you could face prosecution for illegal use and storage of pesticides that are not authorised in the UK.
Is Vinegar Weed Killer Safe for Pets?
Safer than most sprays, but it is not a simple yes and we are not going to give you one. Two things to keep in mind. First, vinegar is an acid: a dog that licks wet leaves or drinks from the bottle can end up with an irritated mouth and stomach. Second, this recipe has a tablespoon of washing-up liquid in it, and detergent does not evaporate the way vinegar does. It leaves a film on the sprayed leaves, and nothing in the method rinses it off. So "dry" is not the same as "gone".
The precautions we would take at home: keep dogs and cats off the area while you spray and until it is fully dry, spray the weeds only and not the surrounding path or lawn, store the bottle out of reach like any other chemical, and if you have a dog that grazes, hose the patch down or pull the dead weeds out before letting it back on there. If a pet eats sprayed weeds and starts drooling, dribbling or being sick, ring your vet or the Animal PoisonLine number at the bottom of this page. For the full method-by-method breakdown across every weed control option, including boiling water, hand-weeding and why salt and glyphosate need more caution, see our pet-friendly weed killer guide.
Frequently Asked Questions
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Safety note. This page is general information, not veterinary or legal advice. Always check a product's own label and re-entry time before use, and if you think a pet has swallowed any weed killer, ring your vet or the UK Animal PoisonLine (Veterinary Poisons Information Service) rather than waiting for symptoms.