You can use chemical weed killers to remove weeds quickly. It's also possible to eventually eradicate a garden of weeds by pulling, digging and smothering, but when you're pressed for time, nothing beats the ease of squirting weeds with chemicals. However, many gardeners are rethinking the use of chemicals---and many are considering vinegar as an ideal, chemical-free option.
Vinegar is made up of about 5 per cent acetic acid and 95 per cent water, according to the University of Illinois Extension. All living organisms already contain acetic acid, and it easily breaks down into water and carbon dioxide. When sprayed directly on plants, the acid in vinegar can dry up a plant's foliage.
Like commercial weed-killing chemicals, vinegar isn't selective. That means if you accidentally spray it on a desirable plant, that plant may become ill or die. In addition, weeds need to be covered thoroughly with vinegar for the acidic liquid to have any effect. Also, perennial weeds cannot be killed with vinegar because vinegar does not move into the weed's roots. Only the foliage is affected, making it suitable only for killing annual weeds.
How it Works
Common household vinegar is rarely effective on weeds, according to the Oregon Department of Agriculture. It contains only 5 per cent acetic acid. Instead, vinegar with 10 to 20 per cent acetic acid must be used. This stronger type of vinegar is 80 to 100 per cent effective, according to the University of Illinois Extension.
Where to Buy It
Commercial food-grade vinegar (often used for canning) sometimes has 10 to 20 per cent acetic acid, but it is not approved by the Environmental Protection Agency as an herbicide. Some states now sell acetic acid as a weed killer, under such brands as Weed Pharm and Bradfield Horticultural Vinegar. These products can be found at gardening centres.
Although it might seem vinegar is safe, vinegar with a high content of acetic acid can cause severe eye and skin burns. Therefore, when applying vinegar to weeds, use great care--just as you would if you were applying chemical weed killer. Wear protective gloves and goggles, as well as long sleeves and trousers. If the vinegar splashes onto your skin accidentally, call the poison-control centre right away.
In addition, animals, children, and other people should stay away from recently sprayed areas of the garden.
Vinegar-based weed killers work best on young weeds. Like chemical weed killers, vinegar should be apply on a warm, sunny day. Thorough application, covering all the weed's leaves, is important. Avoid spraying on windy days, or desirable plants may accidentally be sprayed.