Does salt really kill weeds?
Yes, but it's not a replacement for a proper strong weed killer.
You will have to use an awful lot of salt to get the desired results, most of the time it will simply "stun" the weeds and they'll regrow.
However if you use too much and you may "poison" the soil preventing anything from growing there (at least for a while) - you do need to use a lot.
Do I need special garden salt?
It may sound silly but we get asked this an awful lot.
Any salt will do, even regular old table salt.
Yes, the cheap, nasty 27p salt will kill some kinds of weeds.
Is it safe to use salt as a weed killer?
Salt can be used on most kinds of weeds however it is non selective so it will kill grass, moss & other small weeds, please note, you have to use an awful lot of salt : it's not a replacement for a proper weed killer, it works out more expensive and the results are nowhere near as good.
Want to kill Brambles, Ivy, Thistles, Nettles or any other kind of deep rooted perennial? Don't use salt, it won't work, you can only use salt against small grassy weeds - even then it's effectiveness is debatable at best.
The benefits of using salt as a herbicide:
- It's super cheap and readily available.
- It's natural and is unlikely to do any harm.
- Works quickly and suppresses regrowth.
- Overuse won't harm the environment.
- Can be used near edible crops.
The disadvantages of using salt as a herbicide:
- It's unlikely to be as effective as a commercial weed killer.
- It's non selective and will damage all kinds of plant.
- Deep rooted perennials are likely to regrow.
- You need an awful lot for large areas.
- It's more expensive per m2 than commercial weed killers
- It can harm your soil preventing future growths.
- It can't be used on lawns.
- It may prevent your putting grass seeds down in time.
How does it work?
Salt is easily dissolved in water. When applied to a weed it is quickly absorbed where it makes the plant to retain more water causing it to wilt and die.
It will take up to 10 days to be fully absorbed by the plant. Depending on weather conditions and the size of the weed.
How to use salt as a weed killer:
The easiest, fastest & best way to use salt as a weed killer is to "sprinkle it on"
Just sprinkle it on:
No need to dilute, you can just pour it right from the container onto your weeds and the rain will do the rest.
Yes! It really is that simple, see the rather large weed above?
This is what it looked like just 1 day later...
If you are going to use salt as weed killer this is by far the best method.
Please note your results will vary depending on the type of weeds, time of year and how much salt you used. I cannot stress this enough, salt is not a weed killer!
Yes it will work against some kinds of small grassy weeds but they will likely regrow and if you want the desired results you are going to spend much more on salt than you would vs a commercial weed killer.
In a spray bottle:
You can dilute salt in water and use it in a small spray bottle.
This method is much less effective as you are diluting the salt but if you are in a warmer climate with little chance of rain it allows the weeds to absorb the salt much more quickly.
Typically you want to dissolve as much salt as possible into the water.
This method isn't suitable for the UK, here I would highly recommend you just "sprinkle it on" - the rain will do the rest but watch out for the wind! It can scatter the salt into undesired areas.
In a pressure sprayer:
Just like in a spray bottle only larger! You can cover more areas and dissolve a lot more salt in a 5 litre pressure sprayer vs a standard 500ml or 1 litre spray bottle.
Please note, if you don't dissolve the salt it is likely to clog the hosing on your pressure sprayer.
With hot water:
Boiling hot water allows salt to dissolve more quickly plus it has the added benefit of scalding the weeds, combine salt with boiling hot water and you may just be able to kill of some kinds of weeds - be careful around scalding water and please do not put salt in your kettle!
Just pour the salt right from the container onto your weeds for the best results. By diluting it with vinegar or water you lessen it's effectiveness. If you decide to dilute it so you can use a sprayer then add a squeeze of dish soap to up the effectiveness.
How effective is it?
Salt is effective against small grassy weeds. It is much less so against deep rooted perennials and larger weeds. Salt is cheap and can be bought at almost every store but it is not as good as proper commercial weed killer.
A 27p bottle of salt will treat roughly 1m2, your average weed killer will cost roughly about the same price per m2 (or less) and it will be much more effective.
We used salt to kill some weeds growing around the garden, here are our results after 10 days:
Precautions to take:
Salt is pretty safe as far as herbicides are concerned.
There is no need to use safety gear when using it on it's own.
However it can be harmful to your soil health.
Apply too much salt and nothing will grow in that area for a while (you'd need to apply an awful lot of salt and eventually rain water will wash it away - salt isn't as good as a commercial weed killer)
Salt and grasses don't mix, if your preparing to clear and area to plant grass then don't use salt to clear the area.
The critters living in your soil won't take to being doused in salt either. This may cause long lasting damage to your garden, be careful and remember: DON'T OVER DO IT!
What are the alternatives?
As noted above salt is an excellent herbicide for small scale weed control. If you have invasive weeds or larger deep rooted perennials it won't be effective enough to permanently kill them, only killing the bits it touches.
If you have a large area to cover or large weeds consider these alternatives before using salt:
Just regular old table salt works best - you can buy rock salt they use for de-icing roads but if you are going to spend so much money - just buy a long lasting or strong weed killer
Sorry to bust your bubble but nothing will kill weeds permanently - you cannot stop nature. You can use as much salt or weed killer as you want but if you don't solve the underlying problems the weeds will come back, again & again.
Yes, salt will kill slugs - it dehydrates them.
Salt often won't kill weeds down to their roots for that you will require a strong weed killer such as Glyphosate. It is absorbed by the leaves of the weed then translocated throughout the whole plant killing it from the inside out, right down to the roots.
No, boiling hot water simply stuns weeds. It may kill immature or "baby" weeds but often the weeds will recover after a short period of time.
Salt is about as natural a weed killer as you will get but the easiest and simplest way to kill weeds naturally is to pick them out. Take care to get the head and the root and if needs be use a small trowel to get the whole root system.
Got any more questions? Feel free to post your queries and comments below...