Will Rock Salt Kill Weeds and Grass?


It’s almost a reflex to sprinkle salt to clear the walkway on icy days, but it’s not until the end of winter that we start to think about how all that salt might affect our landscaping. Unfortunately, it’s true that salt runoff can kill the grass and plants that line your driveway and walkways.

How can salt kill grass and weeds? Plants absorb the salt in the soil, leaving them with nutrient deficiency and, in high levels, burning the leaves and causing them to die back.

Snow with salt in it is also damaging when it’s plowed or shoveled onto the lawn or garden. The salt settles into the soil and absorbs water, stealing that water from the plants and causing their roots to dry out, which reduces growth.

It’s undeniable that rock salt kills grass and plants, but there are ways you can make salt work for you.

Related Topic: How to Avoid Dead Spots on Your Grass

How to Use Salt as a Nontoxic Herbicide to Kill Unwanted Grass and Weeds

Although generally something to avoid on your plants, rock salt can be used as a natural, nontoxic herbicide to:

  1. Clear your walkway: Will rock salt kill weeds between pavers? Yes, it certainly will. Use a spray bottle with two-parts salt to one-part water and spray between the pavers or on the grass/weeds trying to come through a gravel pathway or a paved driveway. The weeds and unwanted grass will die out within 10 days.
  2. Control English ivy: It might look pretty climbing up a trellis, but English ivy likes to explore beyond where it’s welcome. As an invasive plant, it can smother trees, blocking sunlight from branches preventing photosynthesis. It can also easily damage old walls or buildings. New well-built construction should hold up fine against it, but if you have English ivy trying to invade, you can spray a salt solution on the leaves to keep it from taking over. Just be sure to protect any plants surrounding.
  3. Kill poison ivy or poison oak: Poison ivy (or poison oak, depending on where you live) is another common pest plant to get rid of. If you’re wondering does rock salt kill poison ivy? Yes, and no. A few applications can kill off the current plant, but to eradicate it, you will need further treatment. Consider consulting a landscaping professional to have poison ivy removed.

Although salt is most effective as a herbicide when it is mixed with water. The recommended strength of the saltwater mixture depends on where you plan to apply the herbicide. For example, if you are applying the salt mixture to weeds in a garden bed with other plants that you don’t want to kill, you should start with a weaker mixture—such as a 1:2 mixture of salt and water.

Alternately, if you are applying the salt mixture in an area where the long-term health of the soil is not an issue (like between pavers, patio stones, cracks in driveway, etc.) a much stronger mixture can be applied such as a 2:1 or 3:1 salt to water ratio. The amount of salt will definitely affect the pH level of the soil over time and could cause it to become infertile.

The Disadvantages of Salt as an Herbicide

Rock salt as an herbicide is easy to access, it’s effective, and it’s nontoxic to your family and pets. But it’s not a perfect solution.

These are things to know about using rock salt to kill weeds.

  • A lot of weeds, a lot of salt: For large sections of weeds, you will burn through an excessive amount of salt before the job is done, and you could permanently harm the soil.
  • Salt is nonexclusive: Salt kills any and all plants. So, if you’re trying to get rid of weeds that are near other plants that you want to keep, consider a different method.
  • Doesn’t reach the roots: For deeper-rooted or more aggressive weeds, you will find that salt effectively kills off the body of the plant, but it still sprouts up again later because the salt didn’t reach the roots.
  • Can ruin soil pH: “Salting the earth” is an ancient practice often used in war to intentionally destroy the ability of the land to grow crops or other vegetation. Inadvertently oversalting your own property will make the affected area unable to grow grass or plants.

Managing Salt Damage

We use salt to de-ice roads and sidewalks every winter and have found ways to make it useful in fighting weeds, but how do we manage all the damage?

  • Apply early: Applying salt towards the end of winter is more damaging than applying early in winter. Allowing the salt to break down and disperse while the roots are dormant limits the damage to the plants.
  • Limit salt use: You can mix in other materials such as sand, sawdust, or cinders to add traction during the snowy months while reducing the amount of salt you use. It also helps to choose a de-icing salt that doesn’t use sodium.
  • Carefully apply: For salty snow, avoid shoveling or plowing it into the lawn or over a garden. For weed killing, apply carefully and make sure not to contaminate nearby plants.
  • Protect plants with a physical barrier: Another way to limit salt exposure is by setting barriers such as a stone border around the garden or on the edge of the lawn to keep the salt from the driveway from washing in. You can also set up a drainage system to direct the runoff around any plants and avoid planting in areas that are a natural runoff.

Related Topic: How to Amend Soil

To Salt, or Not to Salt

Salt can be an effective nontoxic herbicide, but there are areas where it may do more harm than good. Your local Grounds Guys team has a selection of weed control services, including fully organic weed removal. If you want a hand getting rid of those weeds in a nontoxic way, we’re here to help. Give us a call at (888) 972-8063 or request a job estimate online today.

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