A couple of years ago, my lawn mower was stolen, and the thief also made off with my Weedeater and hedge clippers. I bought a second-hand mower that was way worse than second-rate and it was soon taking up valuable shed space while no longer functioning. I followed with a new mower, which inexplicably conked out after two months. A repair got me precisely one more mow before the revolving blade machine failed again. I have taken to scavenging for neighborhoods kids and inquiring about goat rentals to keep our yard from resembling a swamp and having the city called on us.
So I have no time for concern about additional weeds on my property, but if that luxury ever develops, a safe, three-ingredient remedy has been touted on the Internet. This frequently-shared meme promises miraculous results from an amalgam of vinegar, Epsom salt, and dish detergent.
Advocates crow about the homemade product’s near-instantaneousness. Just as digital cameras rendered dark rooms obsolete, this can-have-it-all-now herbicide is said to vanquish vicious vines, dastardly dandelions, and gnarly grass on the same day a homeowner applies the weed killer.
While the claim is strictly true, it comes with a substantial caveat. Just like a deciduous tree that sheds its leaves or a perennial flower that withers in winter, the weeds remain a living organism that will return.
When a yard worker applies a genuine weed killer – i.e., a product made for that purpose – the leaves and stems absorb the ingredients and carry them to the plant’s roots. This results in the weed being executed, not in it being temporarily inconvenienced. The vinegar-Epsom salt-dish detergent lacks this ability and is capable only of choking out top growth. If the weed is perennial or has an extensive root system, it will rebound to annoy again.
Some proponents tout the homemade concoction as being more environmentally friendly than store-bought herbicides, but this is a misnomer.
Writing for Southern Living, Steve Bender notes that household white vinegar contains five percent acetic acid, which draws out the moisture from stems and leaves and immediately turns them brown. The roots, however, are never impacted. The homemade remedy only works on shallow annual weeds incapable of having their foliage torched. To kill perennial weeds with vinegar, one would need to apply horticultural vinegar, which has four times the acetic acid of its household counterpart.
There are multiple issues with this approach. First, the vinegar is an equal-opportunity killer and will zap any plant it comes into contact with, not just the ones you want gone. It will also take out worms and microbes that benefit the soil. Additionally, if used to eradicate weeds sprouting through the sidewalk or driveway, the acidic vinegar acid will begin to break down the concrete. Also, it can be detrimental to humans in the form of blistering skin and eye damage.
As to Epsom salt, it includes two essential plant nutrients, magnesium and sulfur, both of which promote plant growth, not stifle it. Using the salt as weed killer is counterproductive.
The third ingredient in this supposed herbicidal maniac, liquid detergent, serves to reduce the surface tension of a liquid into which it is dissolves. This makes sense and works great when the liquid is dishwater being used to clean up after a yummy helping of grilled cheese and French fries.
When applied as part of a putative weed whacker, it does help the other ingredients coalesce, but again, the final result is futile. Moreover, the detergent can dry foliage and might burn if applied in hot sun, so there’s a remote chance of an unplanned fire.
So after a day of gardening, add some vinegar to your chili, use dish detergent to clean the bowl that housed it, and sprinkle your bathwater with Epsom salt. But leave the weed killing to products designed for that purpose.