Can I Kill Weeds With Salt?

Written by bonnie grant | 13/05/2017
Can I Kill Weeds With Salt?
Salt causes a plant to leach excess moisture and die. (Salt image by lefebvre_jonathan from

Weeds are the bane of the conscientious gardener's existence. They are competitors for nutrients and water that landscaped plants need to survive. In their disorganised growing fashion, they add nothing to the garden and are an eyesore to behold. Environmentally friendly weed killers are the method of choice to minimise damage to the earth. The home is filled with non-toxic weed killers such as vinegar and salt. Salt needs to be used with caution to prevent build-up and burning.

Salt as an Herbicide

Salt can be used as a foliar spray on weeds to kill them. It is useful alone or mixed with vinegar. A diluted salt and water solution is usually sufficient to kill all but the deepest rooted weeds. Boil 1 cup of salt and 2 cups of water and pour into a spray bottle. The application is most effective if it is done before the weeds have seeded, or you will have a new generation of pests in a week.

How it Works

Salt acts as a desiccant, which means it pulls moisture out of whatever it touches. When dissolved in water, the salt penetrates the stoma of the leaves of the weed and can seep into the vascular system of the plant. The result is a mass exodus of the plant's lifeblood. Moisture will abandon the plant, and, as the salt travels to the roots, the salt prevents them from bringing up any moisture. The weed needs water, as do all plants, and it will shrivel and die.


Salt is made up of two components: sodium and chlorine. The two separate when they are dissolved in water. The chlorine is a plant poison that causes leaf scorch, curling and death. Sodium blocks the absorption of magnesium and potassium, which are essential for the production of chlorophyll and an important component of photosynthesis. Without chlorophyll the weed is not able to produce sufficient plant sugars and starves. Weeds with fewer and shallower root systems are affected more quickly.


Salt is a poison in soil when applied in large concentrations. It will remain in the soil for a long time and prevent any green life from starting. Salt should not be applied directly, and the same areas should not be repeatedly salted. High amounts of salt in soil result in drought conditions for plants and prevent them from getting water. The salt spray should be treated with the same caution as a chemical herbicide. Do not spray when it is windy or you may accidentally get the solution on your good plants.

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