In organic gardening, vinegar can function as a natural weed killer. The acetic acid in vinegar gives it the power to kill weeds; the higher the acetic acid percentage, the deadlier it will be. The type of vinegar used for culinary purposes is relatively low in acetic acid (around 5 percent). So if you are serious about weed control, you will need to buy horticultural products with a higher acetic acid content (20 percent to 30 percent) which are available at garden supply and home improvement stores.
The potency of high-percentage acetic acid products used for killing weeds renders them unsafe, so use care when handling. Do not let them come in contact with your skin, and avoid touching your face when using them.
When to Apply Vinegar
When practicing natural weed control, take to heart the dictum: "Know your enemy!" Study up on the weeds you are battling before you use vinegar on them.
Click Play to Learn How to Use Vinegar to Get Rid of Weeds
Learn when annual weeds set seed, so you can target them before this to prevent them from spawning a new generation. Depending on the weed, this can be in the spring or summer. If you catch them in time, one application of vinegar often will be enough to solve your weed problem.
Perennial weeds are not as easy to defeat. Take dandelions as an example. It's a good idea to snap off dandelion flowers whenever you see them, so they don't propagate themselves via seeding. However, while their leaves die back in the winter, these perennials typically live on through their roots. So preventing them from going to seed is not enough. That's where applications of vinegar throughout the growing season come into play. Each time you apply the herbicide, the plant will weaken. With repeated sprayings, a final death should occur.
The Limitations of Vinegar
A commercial weed killer is usually effective after one or two tries because it's absorbed by the weed, reaching the root to permanently kill it off. Vinegar typically does topical damage to the weed unless you can apply it directly to the roots.
Because it's nonselective, vinegar is not an especially effective method for killing weeds in lawn areas. If you do so, you may end up with patches of brown lawn. It makes more sense to use vinegar in areas where lawn grass and other landscaping plants are not in the way, such as on patios or walkways where isolated weeds are pushing up through the cracks.
You will probably have to reapply the vinegar to get the job done. This is especially true of established perennial weeds; vinegar will be more effective on younger weeds and weeds with an annual life cycle. An example of a perennial weed is a dandelion while one type of annual weed is crabgrass.
However, many herbicidal products, including organic ones, usually need a reapplication. So reapplying a natural weed killer like vinegar can be safer if used away from grassy areas. Even then, the high acidic content of herbicidal vinegar could eventually affect stone and other hard materials.
Equipment / Tools
- Spray bottle
- Protective eyewear
- Protective gloves
- Protective clothing
- Face mask
- Horticultural vinegar (20%-30%)
- Liquid dish detergent
Wait for Sunny Weather
Wait for a forecast of at least a few continuous days of sunshine before you apply the vinegar.
There are two reasons why a sunny period is important. First, you need to saturate the weeds with vinegar for it to be effective, and rain would wash off too much of the vinegar from the foliage. And second, the real damage to the weeds begins in the days after the application when the sun hits the leaves.
Before handling strong vinegar, put on gloves, eye protection, and secure clothing. A face mask is also highly recommended in case of splashes and spills.
Mix the Herbicide
Combine 4 parts vinegar to 1 part water. Add about an ounce of dish soap to a gallon of the mixture. Mix well in a spray bottle or other container (if you are not spraying the mix).
When reapplying horticultural vinegar during the summer as the weed growth has slowed down, you can reduce the mixture to 1 part vinegar and 1 part water with a teaspoon or so of dish soap.
The dish soap is a surfactant that improves the effectiveness of the vinegar. For a herbicide like vinegar to have the intended impact, it must stay in contact with the vegetation long enough to penetrate. This is easier said than done because a weed's foliage is often protected by a waxy coating that can repel attempts at penetration. The surfactant helps the vinegar grab onto the weed and remain there so the sun can help it do its damage to the plant.
If you want to zap a few tiny weeds, use undiluted household vinegar (5 percent) with a drop of dish detergent as a quick fix.
Apply the Mixture
Carefully spray or paint the vinegar onto only the weeds you wish to kill. To avoid damaging nearby plants or other materials with the mixture, paint your homemade herbicide directly onto the weeds with a brush.
If you choose to apply the mixture with a sprayer, do not pull the trigger until you are right up close to the targeted weed.
Do not spray horticultural vinegar on plants if it is breezy or windy outside. The vinegar can accidentally spray onto other plants and harm them.