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Vinegar will kill weeds? Yep! A recipe for vinegar weed killer is posted on several gardening sites. The problem is, it is not a very effective herbicide.
The lack of weed control options has been very frustrating for organic farmers, gardeners and homeowners who do not want to use synthetic pesticides.
The idea of using household vinegar as an herbicide is very appealing, it's natural, inexpensive and readily available, but household vinegar is not strong enough to kill most weeds while horticultural vinegar will burn down many.
Horticultural vinegar works very well on annual weeds that will not re-sprout from underground roots or shoots and perennial weeds that are less than 3 weeks old. It is an option to consider for non-selective weed control. However, in most places that a gardener would apply non-selective weed control, a mix of annual and perennial weeds are present and there are better, safer options.
"But vinegar is not an herbicide!" Well...technically, any substance used to deter, damage or destroy weeds is an herbicide.
The acetic acid in vinegar is the active ingredient. When applied to plant foliage, the acetic acid destroys cell membranes causing plant tissues to dry out. Acetic acid does not move through the plant so only the foliage of treated weeds are damaged or killed, the roots are not affected.
Vinegar-based herbicides are contact and non-selective, which means any plant foliage that is sprayed will be damaged. These products can be used to kill weeds growing in patios, walkways, driveways and landscape beds. If used in lawn areas, carefully apply to weed foliage only or surrounding grass will be damaged.
Tips for best results: Apply vinegar on hot, sunny days. It works great on young (less than 3 weeks old) and rapidly growing weeds.
The problem with "home remedies" is that they often haven't been thoroughly tested toxicologically and their impact on non-target species is undetermined, making them potentially more hazardous than synthetic pesticides that are legal. Furthermore, these products are rarely tested in a systematic way for efficacy. Instead, only anecdotal evidence is cited, claims that tend to make the product sound too good to be true. ~ Dr. Timothy W. Miller, Weed Scientist, WSU
Yes, it's an environmentally friendly, natural weed control option, but mixing up a home brew of vinegar weed killer is not the best idea (or very effective). It is better to purchase a product that is labeled for organic weed control such as Weed Pharm.
(For more information, here's a link to Weed Pharm at Amazon.)
It is better to purchase a product labeled for weed control because:
Although not organic, glyphosate is a more suitable choice for non-selective weed control. Contrary to the opinion of the uninformed, it is also safe to handle and won't harm the environment -- when used according to the label directions.
Organic gardening is a very noble pursuit and I'm very much in
favor of reducing or even eliminating chemical usage. Vinegar weed
killer home brews made from food grade products are not very effective.
Glyphosate is safer to handle than horticultural vinegar, and a much
more efficient herbicide. If used according to the label, glyphosate is
safe to use around homes and will not harm the environment.