If you spray vinegar as a foliar spray on the leaves of plants in full sun, most of them will die. Some more hardy plants, English ivy for example, will not be affected. Some weaker weeds will turn black, turn crispy, and collapse to dust, all in 30 minutes when sprayed with vinegar. When you spray in the shade or on a cloudy day, those same plants do not seem to be affected by the vinegar.

If you spray it indiscriminately on weeds in your lawn, the overspray will kill the adjacent grass. I have made a shield for the grass out of shirt cardboard. I drew a line down the middle of the cardboard and a circle in the middle. Then cut the cardboard along the line and cut out the circle. When you put the two pieces of cardboard together with the weed in the hole, you can spray the weed without spraying the grass.

You can sometimes find horticultural vinegar at garden or feed stores. It comes in at 20% acidity whereas household vinegar is 5%. The 20% stuff must be handled with care. Breathing it is not so much a problem because with one whiff you want to leave it alone. The worst problem is getting it in your eyes. It will blind you for weeks or months until your eyes heal. Wear protection and be careful not to splash it near your face or even on your hands (you might wipe it into your eyes).

Apple cider vinegar is vinegar. Spray it at full strength in full sun.

On the other hand, vinegar is a carbohydrate and as such is food for bacteria. When vinegar gets into the soil, nothing seems to happen. It would be interesting to see some research on what happens to the soil microbes when vinegar hits the soil.

Thanks. Just curious why I still have many dead grass blades now. I applied apple cider vineger + molasses last early October. I was thinking that apple cider vinegar might have contributed to the killing of some part of my lawn.

So what I am planning to do sometime May is just use molasses. I'll just use hot water so I'll be able to mix it properly. Cool it down then spray it with my ortho.

Vinegar shouldnt kill anything if you're using end hose sprayer to spread vinegar-molasses mix. It's so diluted, I highly doubt they'd hurt anything at all. We're talking about using straight up vinegar.

Yeah, diluted vinegar is just weak carbohydrates.

Gotcha! Thanks to both of you. :)