[QUOTE=Terryl;1223750]Mix some white vinegar into the weed killer (4 to 6 oz per gallon) it helps the stuff penetrate better.

Some weeds have a waxy coating on the outside, the vinegar helps break that down so the weed killer gets through to do it's job faster.

If you never want anything to grow in some areas, then just sprinkle down some rock salt, works wonders.[/QUOTE
toss a little dish soap into the mix of salt and vinegar...the dish soap helps the solution stick to the weeds. Best used in the sun, it`ll burn the crap out of that weed in 2 days.