Does Vinegar Kill Weeds?

Does vinegar kill weeds, or is it just a DIY gardener myth? After all, we use it in our salads, and spinach doesn’t seem to mind.  

Here’s what science says: Vinegar can permanently kill some lawn weeds in less than 24 hours if applied correctly. However, results vary widely depending on the concentration of acetic acid used, the type of weeds targeted, and how you apply it. Read this article to learn how to kill weeds with vinegar herbicide.

How does vinegar kill weeds?

We say vinegar kills weeds, but its active ingredient, acetic acid, actually does the job. Acetic acid breaks down the plant cell membranes, causing liquid to drain out from the cells. The plant tissue dries, and sooner or later, the weed dies. The process is known as desiccation.

What should you expect when spraying weeds with vinegar herbicide? A few hours after application, plants start to wilt and brown. Later, necrosis develops, and foliage and stems turn black.

Vinegar kills on direct contact

Like most natural herbicides for lawns, vinegar is a contact herbicide. This means it only damages what it touches, typically leaves and stems, and doesn’t travel inside the plant down to the root system, like systemic herbicides (e.g., glyphosate).

If you treat small annual weeds, severe leaf damage can kill the entire plant. Perennials, on the other hand, often regrow from their roots.

Weed killers with vinegar can harm the grass

Are vinegar weed sprays safe for turfgrass? Unfortunately, no. Vinegar is a non-selective herbicide that damages all the plants it touches, including turfgrass and other plants in your yard. 

Use spot treatments to kill the weeds in your lawn or flower beds without harming the plants you love.

Vinegar doesn’t accumulate in the soil

How long is vinegar effective as a weed killer? Even in high concentrations, vinegar doesn’t stay active in the soil for long (experts describe this as “no residual effect”). New weeds can germinate from seed or regrow from healthy roots a few days after a vinegar application.

Multiple applications are usually necessary when using vinegar or other organic herbicides.

What types of weeds can vinegar kill?

While vinegar is a kind of Jack-of-all-trades in your home, its weed-killing abilities have a narrower action field: it works the best on young annual broadleaf weeds and less effectively on perennial species, grassy weeds, and mature plants.

Vinegar is most effective on young weeds 

Apply vinegar herbicide when weeds are up to two weeks old. Here’s why: You need to cover all the leaves of a weed and its growth bud with the vinegar solution to kill the plant. It’s easier when the plant has up to 5-6 leaves. 

Weed killers with vinegar work best on broadleaf weeds 

The more contact surface and time to act a vinegar weed killer has, the more effective it is. This makes it highly efficient when applied to weeds with broader leaves and less efficient when used on grasses.

Vinegar can kill annual weeds

Vinegar is mainly a foliar herbicide, and it is more effective on weeds than it can kill by severely damaging the leaves. Annuals don’t come back from their roots like perennials do. If you spray their leaves with vinegar properly and damage the entire foliage, they’ll die. 

How to use a vinegar herbicide

The vinegar weed-killer recipe

You can spray vinegar on the weeds as it is. Or, you can add some extra ingredients to boost the solution’s effectiveness if necessary. We recommend a solution made of the following:

• 1 cup of liquid soap
• 1 gallon of vinegar (use horticultural vinegar for large weeds).

Liquid soap is a common ingredient in homemade weed killers. It acts as a surfactant, improving leaf contact on weeds with waxy or shiny leaves such as purslane and spotted spurge. 

Most liquid soaps contain carboxylate salts (e.g., sodium stearate) that break the protective waxy layer, allowing the vinegar to cover the entire surface instead of staying in individual drops. 

Household vinegar vs. horticultural vinegar: When spotting weeds in their yards, most homeowners reach for the vinegar in their kitchen cabinets. 

That’s household vinegar, which is made of 5% acetic acid and 95% water. It’s the lowest concentration of acetic acid on the market: effective if you’re dealing with seedlings up to 3 or 4 leaves, but not the best option for older weeds.

Horticultural vinegar, on the other hand, has 20% to 30% acetic acid, it’s more effective with mature weeds and can kill sprayed foliage within two hours of the application. It also requires additional safety precautions during use. 

Any vinegar solution with over 11% acetic acid can burn the skin, trigger bronchitis, and cause permanent eye damage.

Do you need to dilute vinegar to kill weeds? It depends on the initial concentration you’re working with and how old the weeds are:

• Vinegar with 5% to 10% acetic acid is used undiluted. 
• Use horticultural vinegar with 20% to 30% acetic acid as such on mature weeds or dilute to a 5% to 10% concentration for application on weed seedlings.
• Always dilute industrial vinegar with 45% acetic acid. Add one gallon of water to each gallon of vinegar to obtain a horticultural vinegar with more than 20% acetic acid. 

Where can you find horticultural vinegar? At your local garden store, in some home improvement stores, and online. Here are a few options:

• Vinegar Weed & Grass Killer with Sprayer (Amazon)
• 1 Gal. 20% Vinegar Weed Killer (Home Depot)
• Green Gobbler Vinegar Based Weed & Grass Killer (Walmart)
• Harris 30% 128-fl oz Vinegar Liquid All-Purpose Cleaner (Lowe’s)

Do you need salt in your vinegar herbicide? Table salt (sodium chloride) is sometimes added to a vinegar solution because it is more effective at damaging plant roots. However, it is also very toxic to plants and the soil microbiome. 

Unlike vinegar, salt accumulates in the soil. Nothing will grow in the treated area if you apply too much or too often. We don’t recommend using it as an herbicide or in a herbicidal solution unless applied to areas such as walkways, driveways, along fences, or around patios — mainly spots where you don’t want to plant anything.

Where to use vinegar weed killer

Because vinegar is a non-selective herbicide and can damage other plants, we recommend using vinegar solutions primarily for spot treatment in isolated areas of your yard. 

Vinegar weed killer is useful for removing weeds that grow in:

• Cracks in your driveway and walkways
• Around your patio
• Under and around benches in your yard, etc.

If you apply vinegar herbicide to your lawn, take extra precautions to avoid spraying desired turfgrass. 

Note: Vinegar can damage more than plants. Don’t use a vinegar herbicide on materials that are sensitive to its acidic action, such as:

• Wood
• Marble
• Stone
• Granite
• Iron
• Stainless steel
• Rubber or rubberized items

Can you use vinegar as an herbicide in your veggie garden? You can, but with care. One study done on pepper and broccoli crops shows that you can expect some plant injury and a reduced crop yield depending on how much vinegar reaches your veggies. 

When to apply a vinegar weed killer

The best time to apply a post-emergent herbicide like vinegar is a sunny, warm day (over 70 degrees Fahrenheit) without wind or rain. 

If it rains soon after application, the solution will wash away, and you must reapply it.

How to apply the vinegar solution

What you need to spray the weeds with vinegar:

• Spray bottle
• Vinegar solution
• Protective equipment: safety goggles, waterproof gloves, long sleeves and pants

Follow these steps:

Step 1: Keep children and pets away while you apply the solution.

Step 2: Put the vinegar and liquid soap into the spray bottle. Agitate the bottle to thoroughly mix the solution.

Step 3: Spray each weed thoroughly. Remember, the solution kills only what it touches.

Step 4: Repeat the application if weeds reappear. 

How effective is vinegar as a weed killer?

Studies show that the vinegar weed killer solution can control weeds by over 80% when applied to young plants. 

One study was conducted by Charles Webber and his colleagues from Oklahoma State University, who tested the effectiveness of vinegar on broadleaf and grassy weeds. Their results show: 

• Over 84% control on broadleaf weeds like carpetweed, tumble pigweed, and spiny amaranth
• 44% to 63% control on crabgrass when using vinegar with 20% acetic acid

Another study by David Chinery, a Cooperative Extension Educator at Cornell Cooperative Extension of Rensselaer County, showed more than 90% weed control in 24 hours. He applied vinegar on quackgrass, crabgrass, ground ivy, dandelion, broadleaf plantain, and Kentucky bluegrass.

Ways to improve vinegar solution effectiveness

Apply the solution to weed seedlings. The younger the plants, the more effective the vinegar weed killer is. 

Use the solution on lawn and landscape weeds less than two weeks after germination. Most studies show weeds with less than 5-6 leaves are the easiest to kill with vinegar.

Use a horticultural vinegar solution. Large weeds are more resilient to household vinegar because of its low concentration of acetic acid. To improve your chances of killing more mature weeds, use horticultural vinegar with 20% acetic acid.

Make multiple applications to keep weeds under control. Acetic acid herbicides require multiple applications to kill large weeds and keep new growth under control. Reapply the vinegar solution after a two-week break if new weeds sprout or large plants seem to recover from the last application.

Force the weeds to grow faster. This is interesting advice from Marisa Y. Thompson, an Extension Horticulture Specialist at New Mexico State University. 

She explains why forcing weed growth might help: “Newly germinated seedlings have a thinner waxy cuticle protecting their leaves. This is also true of plants growing rapidly (after a rain or irrigation and fertilization). Plants with a thinner protective cuticle are more susceptible to treatment with vinegar herbicides.”

“To maximize your success, water and fertilize the weeds before treatment to encourage rapid, unprotected growth.” Thompson recommends.

Pros and cons of vinegar as a herbicide

All products, even natural ones we use in our kitchens, have advantages and disadvantages. Here are the pros and cons of vinegar weed killers to consider.

Pros of vinegar herbicides:

• It’s a natural herbicide without synthetic chemicals.
• It is low-cost for applications in small areas and easy to find.
• Acetic acid does not accumulate in the soil. Any negative effects are short-term.
• Vinegar can kill young annual broadleaf plants in about a day after application. 
• Vinegar herbicides can be used in organic gardening and lawn care (look for OMRI-certified products).
• It is perfect for removing weeds from grass-free areas such as driveways and walkways covered with pavement, stone, gravel, sand, etc.

Cons of vinegar herbicides:

• It’s a short-term “burn-down” herbicide requiring repeated applications to control weeds.
• Less effective when used against grassy weeds and perennials.
• Covers the yard with a bad smell.
• It can damage desired plants in your yard if sprayed by mistake.
• Vinegar can be harmful to humans, especially when used in high concentrations.
• Some recipes include salt, which is highly toxic to soil, plants, and microorganisms.

Non-toxic and natural alternatives to vinegar herbicide

Homemade vinegar herbicide not your thing? There are other ways to keep weeds under control and still maintain a chemical-free yard. Here are the top nine options to consider:

• Hand weeding 
• Mulching
• Landscape fabric 
• Corn gluten meal 
• Flame weeder
• Groundcovers
• Boiling water
• Rubbing alcohol
• Solarization 

All herbicides are more effective when combined with proper lawn care practices, such as correct mowing, watering, and fertilizing. Keep the grass healthy and thick, and you’ll have fewer weeds to deal with.

FAQ about vinegar as a weed killer

Is vinegar weed killer suitable for organic gardening?

Household and horticultural vinegar can be used as weed killers in organic gardening. However, if you are considering buying commercial herbicides with acetic acid as an active ingredient, you must check if they are approved by the Organic Materials Review Institute (OMRI). Some products contain inactive ingredients that are not considered organic.

The Organic Materials Review Institute is a non-profit organization that reviews and certifies organic products. If a weed killer bears the mark “OMRI Listed,” it’s safe for organic gardening.

How much vinegar to kill weeds?

The vinegar solution must soak the leaves and stems of weeds for it to work. Prepare enough vinegar herbicide to spray thoroughly on every weed you want to kill.

What is 45% vinegar used for?

Also known as industrial vinegar, 45% vinegar is used in a diluted form for tasks such as:

• Laundry
• Dishwashing
• To clean water spots
• To remove limescale, mildew, and grime
• For killing weeds

Leave the weeds to the weed pros!

If spot-spraying the weeds on the lawn is not your idea of spending the afternoon, leave the weed identification and management to the professionals. Find a lawn care company on the Lawn Love website, and watch the weeds disappear and the neat, lush turfgrass take over the lawn!

Main Image Credit: athriftymrs.com | Flickr | CC BY-SA 2.0