For organic gardening, vinegar can function as a handy natural weed killer. It’s the acetic acid in vinegar that gives it the power to kill weeds. The higher the percentage of acetic acid in the vinegar, the better it will operate as a natural weed killer, technically speaking. Vinegar used for culinary purposes is relatively low (5%) in acetic acid, so repeated applications will be necessary when using it as a natural weed killer.
If you’re battling lawn weeds, take care to apply the vinegar directly onto the weeds themselves, not letting it come into contact with your grass. Why? Because the fact that vinegar is a natural weed killer doesn’t mean it can’t be harmful if misused. Vinegar is non-selective, and this natural weed killer can harm your grass!
Vinegar As Natural Weed Killer: How to Apply
Listen to your local forecast, and find out when your region will be experiencing a few continuous days of sunshine. At the beginning of this period, spray or paint the vinegar onto the weeds you wish to kill.
Why is a sunny period required? Two reasons:
You need to saturate the weeds’ leaves with the vinegar, and rain would wash too much of the vinegar off the foliage.
The real damage to the sprayed weeds begins the next couple of days after the application, when the sun hits the leaves.
Some people who use vinegar as a natural weed killer like to boil the vinegar, prior to application. Through such boiling, you may actually be able to gain a concentrate higher in acetic acid, although I haven’t yet experimented with this option in any scientific way. But it certainly can’t hurt to boil the vinegar; in fact, many folks report success killing weeds by simply pouring scalding water on weeds! So I suppose the use of boiled vinegar allows you to attack weeds on an additional front.