How to Kill Weeds With Rock Salt | Home Guides | SF Gate
Nov 28, 2018· Combine 1 cup of rock salt with 1 gallon of coarse sand. Fill a shallow container with the mixture and embed it in the garden soil. Keep the mixture moist to attract butterflies and encourage puddling. The best spot for your puddle is near a drip or soaker hose, where it will always be wet.