I've used it occasionally over the last 15 years or so, and it does work. I've mixed it at two parts vinegar to one part boiling water, or even one part vinegar to one part boiling water - and poured that on weeds that were otherwise difficult to eradicate (as in cracks between paving stones). It temporarily over-acidifies the soil the weed is growing in, and (along with the hot water) actually immediately damages the weeds' roots.

The problem is expense. If you are acquiring vinegar at, say, only a gallon at a time and buying it retail, then it's costly to use. The mixes I've used, while effective, had a high proportion of vinegar in them. The mixture doesn't go that far, if you've got a lot of weeds to deal with that you can't just pull or destroy en masse with a rotary tiller, etc. If you could get the vinegar in larger quantities, perhaps in some food-industry (e.g., cafeteria) volumes, and maybe at wholesale, it might be more realistic.

Joel

In Canada vinegar is a registered pesticide but at an 11%. The vinegar you buy at the local grocery store is usually only a 5% so that could be why you need so much to make it work effectively.

Be very careful not to get the stronger vinegar in your eyes. It can cause blindness because of the acidity.

Will it kill poison ivy!!!!?

I've had good luck with vinegar;
you can get 9% acidity at any store that sells canning or pickling supplies.
Here, that's usually HEB & maybe the occastional Affiliated Store in a small town near a farming area.

I don't know if it'll kill poison ivy, but it's worth a try.

Apply it on a hot sunny day, & if possible cover the plants with plastic to make a sauna.

Although I never have had any trouble with vinegar, it's a good idea to use it on a windless day, or at least stand upwind, & use hand & eye protection.

It might even be possible to get vinegar at even higher % but it starts to become quite toxic and dangerous to use.

Yep, I've used 20% vinegar in the past, got it at Lowe's, don't know if they still carry it.

That's the stuff where you put on goggles & a mask & stand upwind & don't get it on exposed skin.

But 2 heavyish applications one hot summer killed a whole flowerbed full of bermuda grass.

One type of plant that it doesn't seem to have too much effect on are the deep taprooted ones, like dandelions. It will fry the top for a while, and you think Aha! But then the plant recovers.

It works great on plants that have roots closer to the surface.

Sue

Vinegar doesn't seem to have much effect on crabgrass, either. It does help lots on the walkways. I use a spray bottle and cover all the leaves of the weeds. Perhaps a heavier application on crabgrass might help get rid of it?

Of course, crabgrass spreads sooo rapidly....

sigh