Well, yeah vinegar works as a herbicide but so do propane weed killer torches. But “Contact Herbicides” kill only the plant parts contacted by the chemical, where-as systemic herbicides are absorbed by the roots or foliage and translocated (moved) throughout the plant. In the case of the vinegar solution, it doesn’t reach the roots unless the ground is also soaked in the vinegar solution which brings you the problem that you are then changing the soils pH which might very well kill what you are growing too and is considered a misuse/abuse of the application by professionals.
With Contact Herbicide applications the weeds can grow back sometimes a quickly as a week or two. Contact herbicides kill only the plant parts contacted by the chemical, where-as “Systemic Herbicides” are absorbed by the roots or foliage and translocated (moved) throughout the plant.
Roundup or glyphosate is a systemic, which means you spray it on the foliage and it’s actually absorbed through the leaves, goes into the stems, goes into the roots, and kill the entire plant over a short course of time.
And Roundup/glyphosate has a half-life (meaning it degrades) in soil between ranging between 2 and 197 days and a typical average of 47 days depending upon soil conditions meaning it decays. Vinegar on the other hand in the soil remains changing the pH until it is neutralized by adding a base such as lime or limestone. The same is true for any salts. They are permanent until they are washed away and carried downstream (think California’s Salton Sea). That said Epsom salts aren’t necessarily washed away since they are a “Fertilizer” and consumed (digested) by plants for the magnesium in them.
Thinking about that now it makes me wonder if you are trying to kill weed via a vinegar-Epsom salts solution isn’t that a treatment that works against it intended purposes? You are killing the weed by scorching it with the vinegar but then you are fertilizing the roots so it can come back faster. (I will have to ask my landscape/gardener friend Harry when I see him again in the next few days.)
I hate to tell everyone this but if your desire is to garden completely chemical free and vinegar (acetic acid CH3COOH) and Epsom salts (magnesium sulfate MgSO4) are chemicals then the only way to weed is by hand weeding early and often making sure you have pulled the roots. I use an ancient short dandelion weeder tool this help that I have been playing with since I was a little kid.
Get the upper hand on weeding with the Smith & Hawken Weeder. Great for small root removal and perfectly sized for flower beds and small vegetable gardens. Includes convenient hang-up hole for easy storage.
The Ames dandelion weeder is great for removing dandelions and other weeds from lawns and landscape beds. The V- notched blade is sharp to cuts the roots deep below the surface. A leather lanyard makes