Answer:
How long is a piece of string?
Seriously, it depends on the plant your applying it to and a whole host of weather / environmental factors.
In general your weeds should start to die within 3-10 days.
If they haven't by beyond this date apply more salt or get yourself a proper strong weed killer.
Salt isn't a great weed killer. It works well on small or weak weeds.
If you don't want to use weed killers then use an organic method like mulching.
TOP TIP: Find out how to use salt as a weed killer, click here .
Salt can be an effective & natural weed killer.
It's water soluble so it can be sprayed onto the weeds or you can just douse them in raw table salt.
Either method may work but seriously... Salt isn't a weed killer!
How does salt work as a weed killer?
All plants need water to survive.
Salt kills weeds by causing them to dehydrate. When plants are exposed to salt for long periods of time, they lose water and die.
The amount of salt needed varies depending on the type of plant being treated.
You don't need a special kind of salt, table salt works just fine.
How long does salt take to kill grassy weeds?
Salt is highly effective against shallow rooted grassy weeds.
Apply the salt directly onto the weeds you want to kill and they will start to die within 10 days.
How long does salt take to kill weeds on hard surfaces?
Using salt to kill those small pesky weeds between the gaps in your paths? Or maybe you're gravel drive is infested with the blighters either way salt will be effective against smaller weeds in 10 days.
Deeper rooted weeds may take longer and it may not be effective at all.
Will salt kill deep rooted perennials like Ivy, Brambles, Nettles?
Short answer, NO. Long answer:
Maybe, if you use enough salt you may be able to kill off Nettles, Brambles or Ivy but the amount of salt may well permanently damage the soil - if your trying to kill deep rooted or larger weeds then we highly recommend you get an effective weed killer.
When to use salt as a weed killer
Salt is best used against small grassy weeds in dry weather. If it rains a lot in the proceeding days the salt will simply wash away before it has a chance to kill your weeds.
When not to use salt as a weed killer.
Salt generally just kills off the visible part of weeds and doesn't get right down to the roots. This is great for shallow rooted annual weeds like daisies but against tougher foes like Ivy it is unlikely to be effective.
Salt is non selective meaning if used improperly it may kill plants you wish to keep.
If your looking to kill your lawn weeds then please do not use salt, it will kill grass, often permanently.
How to apply salt as a weed killer?
We already have a fantastic salt weed killer recipe, go read it if you intend on using salt as a weed killer.
The easiest way to apply salt is to simply cover your weed directly with salt.
You can also dilute it in water and spray it onto the weeds.