[header] How to kill weeds with vinegar [title] Buy white vinegar. [step] Go to your local grocery store and buy a bottle of basic vinegar, typically a 5% concentration of acetic acid. The best bargain is probably to buy a one gallon jug unless you only have a few weeds. 
If you are killing a lot of weeds, you may need to buy more than one gallon, but one gallon will cover a large area. [substeps] The acid in vinegar is what kills the weeds.