Chelsea Christenson wrote:

My master gardener suggested a solution of vinegar and water for
killing the weeds that come up between the bricks in my patio.
Unfortunately, she's on vacation now, so I can't ask her: what is the
correct ratio of vinegar to water?



I heard about that one time so I took some grocery store vinegar (about
5% acidity) and put it into a sprayer and sprayed some grass etc. in my
gravel driveway. In a couple of days the weeds were dead. In a couple of
weeks the weeds were back.

There may be some plants that vinegar will kill, but the ordinary
hard-to-get-rid-of weeds are not among them. It may set them back a bit,
but don't count on eradication.

I did not try it on poison ivy.