I found this on the internet. Sounds pretty good to me!

Weeds? Gone!! All Natural Weed Killer!! – Helpful Home Tip!
Formula:
1 Gallon Vinegar
2 Cups Epson Salt
1/4 Cup Dish Soap
I Always use Dawn, The Blue Original
You can also put it in your Round-Up or Garden Sprayer. It Worked Fine in Mine.
PUT PACKING TAPE OVER THE RECIPE ON THE SPRAYER SO IT DOESN’T GET MESSED UP!
IT WILL KILL ANYTHING YOU SPRAY IT ON.
I HAVE BEEN USING THIS FORMULA FOR A WEEK NOW, AND I CAN HONESTLY TELL YOU… I WILL NEVER BUY ROUND-UP AGAIN. LIKE I TOLD YOU IN AN EARLIER POST, THIS STUFF WORKS. PERIOD.
JUST MIX AND SPRAY IN THE MORNING, AFTER THE DEW HAS EVAPORATED. WALK AWAY. GO BACK AFTER DINNER AND LOOK AT THE WEEDS. DEAD. PERIOD.
THIS IS SO MUCH CHEAPER THAN ANYTHING YOU CAN BUY ANYWHERE. PERIOD.
AND WITH ALL THE RAIN THAT WE’VE HAD LATELY, THE WEEDS ARE ALIVE AND THRIVING! (OR TRYING TO!)