Haven't tried vinegar myself, but boiling water has worked pretty well for me.

Janet's Garden

Vinegar does work at full strenght. I've taken the whipper snipper and run it through to cut the weeds to the dirt - if you do this when angry it's good therapy and you'll really get the weeds - and then spray. For stubborn weeds, keep at it. It may take a few turns.

I tried regular vinegar (5%) with a bit of dishsoap on an annual grass (plus some other weeds)that grow in my driveway, no effect. I went looking for pickling vinegar (7%), can't find any yet, I suppose later in the summer.

I called the local (Kamloops) IPM hotline, they suggested a product from Scotts - Ecosense, on the label it states acetic acid 6.5 g/l - does that mean 6.5%? If so 2l at $13.95 is ridiculus compared to $4.50 for 4l for pickling vinegar - plus pickling vinegar isn't taxed, it's a food item!

I'll try weed whacking the little beasties so their injured litle cells will suck up the vinegar!

Thanks for the suggestion Tiffy!

Chris

Sorry! This: "acetic acid 6.5 g/l - does that mean 6.5%"
should have read: acetic acid 62.5 g/l - does that mean 6.25%"

Chris

Hi. I found a website discussing this. As you suspected, higher concentrations work best. See excerpt below, and link to site provided.

"The research conducted so far using vinegar shows that vinegar can kill several weed species at different growth stages. Using 10, 15 or 20% acetic acid concentrations, field researchers had an 80-100% kill rate of selected weeds, including giant foxtail up to 3" tall, common lambsquarter up to 5 inches, smooth pigweed up to 6 inches, and velvetleaf up to 9 inches. Using household vinegar (5%) produced variable results but seemed to be the most effective on Canada thistle where a 100% kill rate of the top growth was achieved. Re-growth from the roots, however, continued. Tim Prather, from UI, stated that you could achieve better results by spraying very small plants, 2-6 leaves. Continue spraying at two-week intervals. He's found that the maximum stage for the best kill-rate is the 4-leaf stage."

Here is a link that might be useful: Vinegar as an organic weed killer