My son in law is a landscaper. He uses regular boxed salt to get rid of weeds and it really does work. How nice to find something so cheap and eco friendly to take care of weed problems.
By gem from VA
This page contains the following solutions.
A great, thrifty, non-toxic, and environmentally friendly way to rid spaces of weeds is to simply pour boiling water on them. I use my electric tea kettle and bring some water to a boil. Then I go out and pour the boiling water on any weeds I want to get rid of.
Keep the weeds down for over a year in a rock garden by using white vinegar. It may even last longer than a year. I no longer have weeds in my white rock. It kills everything, so keep it away from the lawn and flowers.
Spray hot vinegar on the weeds. No chemicals, and very organic. To help prevent germination of weeds, scatter corn meal around before a rain.
I have lots of rocks around all my flower beds in my yard. Some are really large, and weeds always found a space to come up in between them.
Most of the rocks that I move are for edging, which would make them around bowling-ball size. The tines of the rake hook onto the ragged edges of the rocks very well, and you can just move them along the ground without having to bend over.