How to Use Vinegar to Kill Weeds
Vinegar Weed Killer
Vinegar can be used as a relatively safe household weed killer without causing significant harm to people, animals, and the environment when used correctly. Vinegar is effective due to its ability to draw moisture out of foliage.
Household vinegar may have to be used in combination with other household items, like salt and dish detergent, to kill mature weeds. Horticultural grade vinegar has a much higher acetic acid content, but should be used only if household vinegar fails to kill targeted weeds.
How Vinegar Kills Weeds
Vinegar is created via a fermentation process and the result is acetic acid. Acetic acid is a desiccant which means it draws moisture out of plant foliage. Vinegar is non-selective and will kill weeds along with any other plant it contacts. Spot treating weeds is the most useful scenario for vinegar herbicide. Some plants may be resistant due to waxy or hairy leaves, so vinegar applications are not always going to be successful.
Household & Horticultural Vinegar
Vinegar contains acetic acid that is toxic to plants, but the concentration of acetic acid is key to provide and effective kill. Household vinegar only contains around 5% acetic acid, which will kill seedlings, young weeds, and even mature weeds depending on how susceptible the weeds are to household vinegar. Always start with household vinegar and spray a few weeds to see how susceptible they are. Apply horticultural vinegar when there is no threat of rain in the near future. If household vinegar does not kill the weeds, then horticultural grade vinegar or a vinegar and salt/detergent combination will be necessary.
Horticultural Grade Vinegar
Horticultural vinegar is many times stronger and more effective against stubborn, mature weeds due to having an acetic acid concentration of 20%. Apply horticultural vinegar when there is no threat of rain in the near future so the vinegar is allowed to be taken up by the plant without rain washing it off. Spray directly onto plants and do not dilute with water. Be careful when spraying to avoid non-target plants. Vinegar is indiscriminate and will kill non-target plants along with weeds. Avoid over-spraying as much as possible.
Reapplying vinegar is usually necessary, especially against weeds like crabgrass. Vinegar does not linger in the soil and prevent new weeds from sprouting. Spray new weeds immediately for maximum effectiveness. Reapplication is a slight downside to using vinegar as a chemical herbicide alternative.
Vinegar Weed Killer Mixtures
Vinegar Weed Killer Combinations
Salt & Vinegar - Mix 1 & 1/2 cups of table salt into 1 gallon of household vinegar. Mix thoroughly so all the salt dissolves. Undissolved salt will settle on the bottom of the sprayer and may even plug the sprayer nozzle. Apply by spraying onto target weeds.
Salt is very effective in tandem with vinegar, but salt solutions can cause damage by soaking into the soil and spreading into non-target areas and plants. Be very cautious and use sparingly when applying salt solutions since non-target plants and lawns in the direct vicinity can easily be killed. Salt remains in the soil for a while and may cause lingering problems in other plants. Salt is best used against weeds in sidewalks, patios, and other hard surfaces.
Dish Detergent & Vinegar - Mix vinegar with a few squirts of liquid dish detergent into a sprayer or small spray bottle.Apply the mixture by spraying during the sunniest and warmest part of the day. Hot summer days provide the best results because the soap will dry into a film on foliage while helping lock in the vinegar.
Reapplying of mixtures is usually necessary, especially against resilient weeds. Such mixtures do not remain active for very long which allows new weeds to emerge. Spray new weeds as soon as possible.
Treat Vinegar Weed Killer as a Chemical Herbicide
Use vinegar and vinegar mixtures like every other herbicide and pesticide. Just because it is a common household item does not mean it can be used carelessly. Injury can occur to people, pets, and the environment if used recklessly. Every weed problem has its own unique scenario and blindly spraying vinegar and vinegar mixtures is highly discouraged. Also, household vinegar should be tried before resorting to stronger horticultural vinegar. Stronger is not necessarily better.
Acetic acid in vinegar can cause:
- Eye irritation or burns
- Skin irritation or allergic reaction
- Digestive tract reactions or damage
- Respiratory tract irritation
Read container label carefully before applying horticultural grade vinegar.
Vinegar Weed Killer Poll
Have you used vinegar as a weed killer?
Questions & Answers
I am getting ready to use a solution of 30% vinegar diluted down to kill some weeds, but will it kill the good grass?
The grass may be killed. It is best to use a vinegar, salt, and detergent solution to spot-treat weeds.
Will vinegar kill poison hemlock?
Yes, but repeated applications of vinegar may be necessary to kill weeds.