Will Borax Kill Grass?

When spraying herbicides to kill grass growing along the side of the road, some government contractors use a combination of boric acid and other chemicals. If you have problem grass growing around your home, you can use a related compound – borax.

Borax

Borax is a naturally occurring compound. It takes the form of a soft powdery soil. Containing boron, sodium and oxygen, borax is sold in garden centers and home improvement stores. It usually is used as an insect killer and also can be used as a cleaning product. When applied to grass, it acts as an herbicide. It draws moisture out of plants, causing them to dry out and turn brown. Borax also interferes with a plant's ability to photosynthesize nutrients, starving it.

Application

To use borax to kill grass, first add 10 oz. of borax to 4 oz. of water. Once the two are thoroughly mixed, pour the mixture into 1 gallon of water. Use a sprayer to apply the mixture to all the problem grass you need to kill. The grass will turn yellow and brown, then wither and die. You might need to apply the borax mixture again to kill all the grass. Wait about a week between applications. After the grass has died, rake it away and dispose of it.

Drawbacks

While borax can kill grass, it is most effective at killing problem weeds in small areas, like those growing in between bricks on a patio or in cracks in a sidewalk or driveway. Borax can have trouble killing established grass, especially if it is planted over a large expanse. The ratio of borax to water needed to kill grass is higher than that needed to kill weeds, and the chance of having to reapply the mixture is higher with grass.

Considerations

While borax has relatively low toxicity for humans and pets like cats and dogs, it can make you ill. Wear a mask and eye protection while working with it to reduce the risk of eye and respiratory irritation. If a child or pet gets into borax powder and eats it, they could experience nausea, diarrhea or vomiting. Store borax where children cannot access it. When applying borax to grass, keep children and pets indoors and away from it until the borax mixture has had time to dry thoroughly.