Kill Weeds the Natural Way – Vinegar

I’m always surprised at how many gardeners don’t know that vinegar can kill weeds.

I’m talking about strong vinegar – at least 10 percent acidity. The vinegar sold in grocery stores is usually less than 10 percent acidity, and that’s not strong enough. You can find stronger vinegar in many garden centers and farm and ranch stores. Many of them offer 20 percent vinegar, and that’s what I use for killing weeds.

Vinegar acts as a broadspectrum herbicide. It will kill the foliage of anything you spray with it. It will utterly destroy most of the annual plants we think of as broadleaf weeds. It will also kill vegetables and flowers, so be careful where you spray it.

It can kill grasses and other perennials, but many grasses grow from rhizomes or “runners” at or just below the soil surface. Vinegar will kill foliage above the surface, but it may take several applications to completely kill the patch of grass. Sometimes it’s easier to just dig it up. Similarly, vinegar will defoliate woody shrubs and trees, but it probably won’t kill them outright. It works great at killing weeds that pup up around the garden borders and in walkways It’s simple to use: just pour a gallon of vinegar into a pumpup sprayer and spray any plants you want to kill. Don’t dilute it.

I usually add an ounce or two of orange oil and a few drops of Dawn dish soap. The orange oil seems to boost vinegar’s killing power. And Dawn dish soap helps the mixture stick to the leaves.

Spraying vinegar works best on hot, sunny days. If it’s a dewy morning, wait until the dew dries from the leaves before spraying. The weeds will turn yellow and die within a few hours.

Some homemade herbicide recipes that call for kitchen vinegar include salt. That’s because five-percent kitchen vinegar isn’t strong enough to kill weeds by itself. But by including salt, you can increase the salinity of your soil, and that’s not a good thing. Instead, stick to strong vinegar in the 10 to 20 percent range.

Some stores sell even stronger vinegar, 30 percent acidity or higher. I avoid these. Vinegar that strong can burn your skin and cause serious medical problems if you inhale it or get it in your eyes.

Vinegar corrodes metal. So flush out your sprayer after use, or the vinegar will rust any metal parts inside.

Lots of folks use Roundup to kill weeds. It certainly works. A jug of pre-mixed Roundup with a spray wand typically costs more than $20. The concentrate costs well more than $100 a gallon. But the company that makes Roundup, Bayer/ Monsanto, recently settled a cancer lawsuit for $11 billion. If you spray Roundup, or any other toxic herbicide, you need to be really careful about covering your skin and face. But what about dogs and cats that walk around naked and barefoot? If this concerns you as much as it does me, please give vinegar a try.

You can usually find a gallon jug of 20 percent vinegar for under $20. And humans have consumed vinegar for thousands of years with no ill effect.