Does vinegar kill weeds?
No! Vinegar doesn't really kill weeds - yes, you heard that right here, vinegar is a poor weed killer.
Vinegar is great on chips and elevates a packet of crisps to god tier but let me be straight with you - it can be used as a weed killer but it isn't very effective.
The active ingredient in vinegar that kills weeds is acetic acid, not all vinegars are equally effective at killing weeds. To be effective, the vinegar must have a high concentration of acetic acid, typically above 10% and in some cases even 20%.
Regular household vinegar, which is usually only 5% acetic acid, may temporarily wilt weeds but will not kill them permanently : they'll simply regrow.
Do I need special vinegar?
Using less weed killer in our daily lives is commendable and should be encouraged but regular vinegar is a poor weed killer, it will simply stun the weeds.
Many enterprising companies are now selling "agricultural vinegar" which contains higher amounts of acetic acid (often 20%+) this isn't vinegar, it's just another commercial weed killer.
Acetic acid can damage eyes, it's harmful to insects and it's not a very good weed killer: it simply burns away the visible part of the plant, leaving the roots intact.
How does it work?
Acetic acid burns away the parts of the weeds you apply it to.
Is it safe to use vinegar as a weed killer?
If your using regular ole vinegar you would put on your chips then yes it is 100% safe to use distilled or malt vinegar as a weed killer - it may not be very effective but it will be safe.
Agricultural vinegar with a higher concentration of acetic acid is much more toxic than regular vinegar. Infact in one study it took less acetic acid to kill rats than it did Glyphosate (the worlds most popular weed killer) - if you decide to use agricultural vinegar then be sure to read the label.
Benefits of vinegar vs commercial weed killers?
- It's relatively cheap and readily available.
- Can work very quickly, sometimes taking as little as couple of hours to eliminate small weeds.
- Once sprayed it isn't likely to be harmful to the environment, your pets or your children.
- Damages most kinds of weeds.
- No need to exclude kids or pets from the area.
- Can be used in areas with edible crops.
What are the disadvantages of using vinegar?
- Higher acidity means much more danger.
- May not kill the weeds, just stuns them
- Isn't as effective as commercial weed killers.
- Cannot be used on lawns.
- Lower acidity vinegars may not work at all.
- Can affect soil PH if over sprayed.
How to use vinegar as a weed killer:
There is no need to dilute vinegar, it's already in liquid form which makes it easy for the plant to absorb. Diluting it will only decrease the effectiveness.
Pour it on or spray it on undiluted:
Simply spray it onto the weed covering the leaves & stems.
Be careful not to get any on any plants you wish to keep and don't allow the vinegar to seep into the soil if you plan on replanting after killing the weed.
Do not use vinegar to kill weeds in grass unless you want to kill your grass forever.
If your using agricultural vinegar please read the label and follow the instructions for safe use.
How effective is it?
I know you have probably heard all over the internet that vinegar is an effective weed killer but it isn't. The 20-30% acetic acid "agricultural vinegar" can be used to kill weeds but it needs to be used more often than a regular weed killer such as Glyphosate.
Regular vinegar you buy from almost every shop is not very effective, it may stun or weaken some small grassy weeds but they will recover.
Agricultural vinegar is a contact killer, for the most part it will only kill the parts of the weed it touches. It won't travel through the plant and kill the roots like most commercial weed killers.
Neither type of vinegar will kill deep rooted perennials like Dandelions, Brambles etc.
Don't believe us? As you can see in the pictures above, we applied a whole bottle of distilled vinegar to a small amount of weeds, see the gallery below, the weeds have certainly weakened but they are still there after 10 days!
Vinegar isn't a very good weed killer. Distilled or malt vinegar will only stun your weeds and "agricultural vinegar" just burns away the visible part of weeds.
Vinegar can lower the PH of your soil making it more acidic and inhabitable for plant life, please don't overuse it.
On that note, if you're clearing an area of weeds and wish to plant something there like putting down grass seed then leave plenty of time between application and the start of seeding a new lawn, this will give your soil PH time to recover.
What are the alternatives?
Weed control is an emotive subject and many recommend against the use of commercial weed killers such as Glyphosate or a long lasting one.
In all cases it's better to take a pro active approach to stop weeds from growing in the first place.