Ordinary dry table salt does a great job of killing weeds. Check the runoff situation, though. If the salt drains into your flower bed, it will kill your flowers too.
I personally have had great results with salt killing unwanted weeds, especially obnoxious ivy that has grown back every year using 'traditional' chemicals... salt is safe for the environment too.
No way. To the extent salt kills weeds, it kills other plants too. In fact, your weeds would probably be the last members of your garden community to expire from salt exposure.
