Wherever possible, I prefer to find organic solutions to garden
problems. Several readers have asked me about using vinegar to
QUESTION: "I am looking for some info on organic weed killers. I have
numerous recipes for organic weed killers with testimonials on how
effective they are. They all call for high acidic vinegar or
industrial vinegar. I have searched high and low and have not found
where I can purchase this miracle of modern man! I have been in the
gardening business for years and have had my own business for the past
three years (organically based as much as my customers will allow) and
find myself feeling grossly inadequate when it comes to this. If you
could please let me in on your wonderful wealth of knowledge and pass
on the golden key, it would mean the world to me." - Laurie Orsini
ANSWER: There is quite a lot of research under way into the
effectiveness of vinegar as a weed killer. I found a online article
that you should definitely look at. You can read it at
The writer, Patricia Diaz, notes that regular household vinegar is a
5% acetic acid concentration. While this works on some weeds, a
greater concentration is needed for other or more mature weeds. By
distilling, a 15% concentration can be obtained, and a 30%
concentration can be obtained by freeze evaporation. These
concentrated acetic acids, if they are derived from plant sources and
not from chemicals, are acceptable for agricultural use by the organic
The vinegars used in the field tests came from three sources: Knouse
Foods, Biglersville, PA, Burns-Philip Food Inc, Baltimore, MD and
Heinz USA, Pittsburgh, PA. Be cause the studies are still in their
infancy, I don't believe these companies are offering these highly
concentrated vinegars to the public, but you might try contacting
Note that vinegar with acetic acid concentrations greater than 5% may
be hazardous and should be handled with appropriate precautions.
You can learn more about the use of vinegar as a weed killer at this
USDA site: http://www.ars.usda.gov/is/pr/2002/020515.htm
Aside from pulling all the weeds out, Cheryl and I have found the best
solution is to use organic material to build the soil. If you keep
soil healthy, weeds do not seem to do as well. Most of the time you
see weeds growing where more desirable plants have a tough time.
Again, this is because there is some kind of deficiency. Calcium
deficiency is a common cause. Organic products such as Turf Tea
Quality Grow, Prosper Soil Conditioner and Smart Coral Calcium can be
effective in building healthy, robust soil.
QUESTION: "I have a question regarding a column of yours that was
published in the newspaper on July 19, 2006. In the article you
discuss the control of the Japanese beetle with the use of "milk
spore." Since then, I have asked several area nurserymen if they have
this product. None of them had heard of it. Can you please give me
more info regarding this?" - Carol Schick
ANSWER: Milk spore is safe around pets and children but kills grubs.
It is considered a disease, but it only affects beetle larvae (grubs).
Once built up, milk spore can remain dormant in the soil, only
reactivating when new grubs appear. It is applied in powder form,
using approximately 10 lbs per acre. Here is a useful link I found for
Look for the section on "healthier pest control."
You should be able to buy Milk Spore powder at larger garden centers.
It's also available online. You can find suppliers by Googling "milk
spore powder." I hope you are successful in your battle against the
The Plant Man is here to help. Send your questions about trees, shrubs
and landscaping to firstname.lastname@example.org and for resources and
additional information, or to subscribe to Steve's free e-mailed
newsletter, visit www.landsteward.org