I read an article on the internet that said that white vinegar is a good weed killer. Since its best practice to not trust anything you read on the internet until you verify it, I decided that this was an opportunity to run my own experiment.
So on June 25, 2013, I sprayed a undiluted White Vinegar on some weeds and 24 hours later the weeds were mostly dead. Here’s the before and after picture.
However, a month later – August 1, 2013 – I noticed that the part that still had some green in the after picture grew back. So I asked myself would second application of white vinegar killed them completely?
So I ran a four part, two phase experiment. For the first two groups I used fresh-from-the-bottle white vinegar. For the third group I used the spray bottle from the first experiment, which had some left over white vinegar in it. The vinegar had been in the spray bottle for a month which was not an air tight seal. The control group were weeds I just left alone.
Phase 1 results: For the first two group (fresh white vinegar) the results were identical as the first experiment. For the third group the effect was minimal impact on the weeds. There was an impact compared to the control group, but not anyway near as significant as the groups using fresh-from-the-bottle white vinegar. Also, the weeds in the third group did recover over a two week period.
For Phase 2 of the experiment I sprayed fresh-from-the-bottle white vinegar on the first group that had been sprayed the day before and left the second group alone. 24 hours later the first group was almost completely dead compared the the second group.
Conclusion: White Vinegar does work as a weed killer, but not as well as non-organic weed killers. However, it works good enough. A second application of white vinegar almost matches the results on non-organic weed killers without the side problems. The white vinegar must be fresh from the bottle to be effective. If it has time to “breath” then it loses its effectiveness.