Preliminary Report: 5% Acidity Vinegar Works Like a Charm!

Myrtle recently expounded upon the possibility of replacing chemical herbicides with common household vinegar.  This set off a teapot-style-tempest over the possibility that 5% acidity vinegar could, at any level of application, be as effective as horticultural vinegar, which comes at a 20% acidity level.

We are quite happy to report that Myrtle was correct:  5% acidity vinegar does the trick just fine, although much larger quantities are required in order to achieve complete eradication of weeds.

Anecdotal evidence found on numerous organic gardening bulletin boards offers the following advice:  if you want to permanently defoliate an area, add salt to your vinegar mixture; if you merely wish to defoliate weeds prior to planting desirable crops, just use vinegar, maybe with some citrus oil added to it.

Now Myrtle can add her experience to the voices of those recommending vinegar; the following pictures and observations are from 2 hours into our experiment; obviously, we will be monitoring and updating as we have more recommendations; we also have some hypotheses which will require further testing.

We applied roughly one quart of 5% acidity household vinegar to a patch of weeds in our driveway comprising approximately 40 square feet (roughly 2 feet by 20 feet, on an arc); we left a control patch of weeds in the same swath of sunlight, and in the same gravelly conditions, for comparison.  Application was done with a common household window cleaner sprayer device, using the "spray" rather than "stream" setting for broadest application.

We did not soak the plants to the roots, so our expectation is that without further treatment, weeds will return regardless of success or failure of this experiment.  However, we did completely cover all exposed foliage.

Two hours after application, the control patch retains its original green and vibrant foliage, and shows no signs of stress.  The treated patch is yellowing and browning, and is dry and brittle to the touch; where we attempted to remove it, the foliage pulled easily away from the base of the plant.  As expected, the root was not dislodged by this cursory treatment.

Several conclusions can be reached even this early in our experiment.  First, vinegar even at low concentrations is a highly effective defoliant.  There is absolutely no need, and given the mounting evidence of danger, absolutely no defense, for the use of chemical herbicides.  It is an indefensible, inexcusable practice.

Second, for vinegar to be completely effective at lower acidity levels, a soaking treatment will be required.  To kill the roots, the roots will have to be exposed to the citric acid in the vinegar: QED.  We do not yet know what quantities will be sufficient for this kind of treatment, but again, it will almost definitely not be an excessive amount; if 20% acidity vinegar works at a treatment level of 80-160 gallons per acre, we are fairly confident that the same application levels will be sufficient with the levels available in vinegar you can buy from your local grocer.

As a final note, grocery stores in College Station appear to carry two different acidity levels:  5% and 9%.  We have seen a lot of literature discussing 7% vinegar, but none regarding 9% vinegar.  We may run tests at that higher level soon, but given our success at lower levels, we are not sure such tests will be necessary.

Next up:  tests on soaking level applications to our new vegetable beds for our fall garden!

Happy weed killing!

Happy farming!