Can salt be used to control weeds permanently?

Question

I was reading over here that salt can be used to control weeds in paved areas?

1. Is salt an effective way to kill all (or most) plant types?
2. Is it permanent?
3. Will using salt effect ground water (I have a bore) and nearby gardens?

Answer 1

Yes, salt will kill plants. In theory, if you use enough of it in the soil, it will kill a tree.

Regarding whether its permanent, no, its not. If you saturate open ground with salt, everything dies, and, by and large, nothing grows for some months, even years. In your case, you want to know whether it works permanently when its been applied to paving. No, is the answer, it will wash through eventually, so you will need to re apply.

Yes, using lots of salt to kill weeds will affect ground water, although how much its affected depends entirely on how much you use and how often. A small amount occasionally is unlikely to cause much harm.

But there is one other factor to consider - salt damages concrete and other paving materials. Damage occurs from the use of salt/grit mixes on concrete or paved surfaces as a de-icing solution - it's more likely to occur when used neat on paving, even if you're trying to only get it in the cracks. It is toxic to plants and other forms of life within the soil, and the risk of run off onto planted areas when it rains should also be considered.

Personally, I would not recommend it. The use of salt as a weedkiller because it's believed to be 'organic' and less toxic than a commercially available tailored-for-purpose path weedkiller is erroneous - salt, used frequently, is much more toxic in comparison to one or two applications of path herbicide a year, assuming the herbicide is intended for amateur garden use rather than professional agriculture.