Maybe I’m just cranky because it’s Monday, but I’m still bothered by a video I saw this morning touting a homemade weed killer.
The video, published by an online news organization that shall remain nameless, suggests killing weeds with a mixture of vinegar, salt and dish soap. The man in the video makes it sound like a no-brainer. It’s nontoxic! It’s effective! It’s made from stuff you have around the house!
What’s not to love?
Well, a few things.
Let me pause here to put on my master gardener volunteer hat.
For one thing, the acetic acid solution in household vinegar is probably too weak to be all that effective on plants. It may kill the part of the plant you can see above ground, and it might even kill the entire plant if that plant is young enough. But vinegar won’t travel to the roots, so it will be ineffective on perennial weeds. You can read the University of Illinois Extension’s information on the effectiveness of vinegar on weeds here.
The video claims the salt in the solution will travel to the roots and kill them, but I don’t think I’d be putting any salt in my soil. Excess sodium can hamper plants’ ability to take up water and make some nutrients unavailable to the plants.
The bigger issue here is that lots of people assume homemade fertilizers and weed killers are benign because they’re made from nontoxic or even edible ingredients, but that’s not necessarily the case. The problem isn't just that they might be ineffective. It's that some can harm the soil or the environment.
I’m reminded of a community garden in the Akron area. When the garden’s production dropped precipitously a couple of years ago, the organizers turned to the Summit County master gardeners for help. A soil test revealed an excess of magnesium in the soil, caused by the liberal use of homemade fertilizers containing Epsom salts.
I’m not saying all homemade fertilizers and weed killers are bad, or even that you shouldn’t use Epsom salts. But don’t accept claims of the merits of homemade mixtures blindly. Do your homework and make sure claims of their effectiveness have been proven by research. And for goodness' sake, get a soil test so you're only giving your soil what it needs.
University extension services, such as the Ohio State University Extension, are great sources of research-based information. You can also call the master gardeners in your area for research-based advice. In Summit County, they operate a hot line from 9 a.m. to noon Tuesdays during the growing season at 330-928-4769.
And I don’t care what he calls himself. The guy who advocates using tonics made from stuff like ammonia and molasses is not a certified master gardener.
OK, I feel better now.