Natural Weed killer

I recently came across a blog that gave a recipe for a "Natural Weed killer" consisting mostly of vinegar, salt & dish soap. http://fullofgreatideas.blogspot.com/2011/07/natural-weed-killer-made-with-basic.html It even gave pictures of how quickly weeds were killed in a paver driveway. My concern with this concoction is how long does the vinegar & salt stay in the ground. I have one flower bed that is plagued with some type of running grass that I cannot seem to get rid of due to the underground runners. Even if I don't directly spray the flowers, would this solution get into the soil & eventually kill the surrounding flowers?
Jo-Ann

Oh jeese, if you have doggone WIREGRASS you can quit worrying about salt and vinegar...

The vinegar will contact kill and shouldn't remain in the soil long. Horticultural vinegar (20% solution, as opposed to the 5% you get in the grocery) is the most effective. The dish soap acts to help the mix 'stick' to the plant. Most effective on herbaceous plants - the underground runners are likely to come back since the vinegar won't contact them and the plant won't soak it up and deliver it to the roots systemically.

The salt can accumulate in the sol and should be avoided. Think of the phrase "salting the Earth" - this was done to enemy's land to keep anything from growing!

Vinegar &Salt let set mixed for an hour roughly makes a mild Hydrochloric Acid ,
If the weather is dry and very hot it burns a plant down in a couple days .
It will burn you also if left on your skin , so don't let that happen .
With cooking spray it makes Hydrochloric oil .
It would work better if I could find a water resistant to add to it ) (the mix were talking about)so it stays longer or works in cooler weather .(that's where I'm at with this idea .)

Anything that will kill a difficult plant will certainly kill a less difficult plant. Personally, I would smother (no light) or solarize (clear plastic to overheat) plants with stubborn roots before I would use either salt or 20% vinegar.