Please repeat the weed killers.

You can use 3 cups white vinegar, 1 cup salt and 2 Tbs dishwashing liquid. Mix together and use in a spray bottle. Do not get on good plants because it will kill them. Just spray the weeds, and they will begin to die within a couple of days. Use when plants are dry...not right after a rain.

Can this be used on weeds in the lawn, or will it kill the grass if it gets on it?

Try this site with 13 Homemade Organic Weed Killers from Good Housekeeping: http://www.goodhousekeeping.com/home/gardening/advice/g777/homemade-weed-killers/  ; Good luck!

23% acetic acid (horticultural or industrial vinegar) works all by itself without the salt. The diswahsing liquid is a 'water wetter" or surfactant purpose - hs nothing to do with killing the weeds or anything else this vinegar touches.