Does Dish Soap Kill Grass? Yes, But Here’s Why!


Does dish soap kill grass or cause damage like brown spots?

Applying enough dish soap to grass will kill the plant because it will wash off the protective oils and wax the grass naturally produces to protect the foliage from the sun, heat, water, pests, and diseases.

Dish soap is standard in DIY garden sprays, and activities like washing your car include soapy water running into the grass, so it’s critical to know how much is safe before it destroys your lawn.

To avoid killing your grass, below I explain why dish soap gets on grass, how to prevent issues, and if Dawn dish soap is safer than other brands.

With the right dish soap, you can take care of household chores or let your kids play in the grass without worry!

Will Dish Soap Kill Grass?

Dish soap and water on your lawn will break the surface oils on grass blades, leaving any area touched by the soapy water vulnerable to damage. The higher the concentration of dish soap, the faster the grass will show brown spots or die.

Most death of grass from dish soap is from the blades drying out due to a lack of wax and oil barrier on the surface. If the dryness doesn’t kill the grass, diseases or pests will finish the weakened plant.

Does Dawn Dish Soap Kill Grass?

Dawn is the most popular dish soap brand people use for homemade weed or pest killer and for washing grimy vehicles because it has a high concentration of grease-cutting chemicals, so you need less product.

Direct application of full-concentrate Dawn on grass will kill it and the foliage it contacts.

While Dawn is excellent for washing away road grease and oils on your vehicle, any soapy water that flows into your grass will instantly cause damage to the lawn if you don’t take steps to lower the harm.

It helps to remember that dish soap is actually a detergent, which is much harsher than natural soap.

Always do a spot test to see if your soap will cause harm to your lawn! Place a small peg in the ground where you do the test so that you can check for any signs of damage the following couple of days.

Dr. Bronner’s 18-in-1 Soap is a dish soap that may be safe for grass that biodegrades into harmless nutrients and includes oils to prevent stripping grass blade surfaces and drying them out.

Most dish soap formulations include boron, chlorine bleach, and sodium, all toxic to plants.

Boron is a micro toxin that can damage plants even in small quantities. Because boron isn’t harmful to humans, it’s a common additive in “eco-friendly” products.

Chlorine bleach is a powerful antiseptic and kills all bacteria, even the beneficial varieties in soil that help plants thrive. Chlorine is standard in many antibacterial dish soaps.

Beware of 7th Generation dish soap or laundry detergents, as even though they claim to be natural, they still contain boron and salts that are harmful to grass.

Slip And Slide Soap That Won’t Kill Grass

If you must use soap to reduce friction on a slip and slide, use gentle baby shampoo with a no-tears formula like Johnson’s Head-to-Toe Gentle Wash & Shampoo since it’s hard to avoid getting soapy water into your eyes during the fun.

Many grass-safe dish soaps won’t provide the suds to keep the slip and slide slick, even if they contribute oils.

Quality baby shampoo will be free of dyes, sulfate, phthalate, and paraben, and when the fun is over, you can hose down the grass to disperse any remaining baby shampoo to safe levels.

Why Dish Soap Gets On Grass

Here are the reasons you may need to use or get dish soap on grass:

To Make a DIY Weed Killer

Dish soap is a common ingredient in DIY weed killers, but it’s next to impossible to avoid getting the solution on the grass when spraying the weeds.

The purpose of dish soap in a homemade weed killer solution is as a surfactant. A surfactant lowers surface tension on the foliage of weeds, so the weed-killing ingredients can absorb into the leaf pores and kill the plant.

Surfactants also strip oils from the leaves, drying them out and leaving them vulnerable to diseases or fungi. You can use strictly dish soap and water as a weed killer, applying it regularly until you see the plant wither and die.

If you’re not careful, overspray will happen when applying a dish-soap weed killer on your lawn, damaging the surrounding grass and causing ugly brown spots or dead patches. Using a cardboard barrier around weeds can help reduce overspray during application.

To Make a Homemade DIY Pest Control Solution

Dish soap is a standard ingredient in homemade pest control solutions for ridding your lawn or landscape plants of harmful insects or other pests.

The surfactant ability of dish soap is why it’s a crucial ingredient, along with vinegar or other chemicals that will soak into the foliage or down to the root system to kill parasites, bacteria, fungi, insects, or other garden pests.

Using grass-safe dish soap will allow you to treat infested lawns or plants without killing the grass, only the pests.

When Washing Cars or Equipment

Washing your vehicles, pets, or home goods like rugs outside means it’s very common for the soapy water to flow into your grass. If you use the wrong soap for this task, you risk harming your grass.

It always pays to buy car wash soap and not create a mix of water and dish soap for vehicle cleaning. Car wash soap formulation will protect a vehicle’s wax and paint job, which does not strip wax or oils from the surface.

Dish soap is full of chemicals and bleach made to break down oils and grease so that they will strip a car’s clear coat and wax layer. Unfortunately, the result is that the dish soap water harms your vehicle’s paint job and damages any grass the soapy water contacts.

When Using Kid’s Toys or Play Gear

Fun outdoor play with kids often includes using bubble machines or slip and slides that require a soapy solution to work.

As a bubble machine operates, it’s typical for excess bubble solution to drip down the sides and onto the lawn. With the cost and hassle of buying ready-made bubble solutions, most parents opt for low-cost dish soap concoctions.

Dripping several drops of dish soap on a slip and slide plastic will reduce friction and make using the outdoor toy much more fun. But, in the process, water and dish soap will run off the sides of the plastic sheeting and get onto your grass.

In Summary

Dish soap will kill grass if you expose it to a high concentration of soapy water or regularly douse the area with soapy run-off, and don’t spray it down heavily with a hose afterward. Luckily, you can use a dish soap safe for grass when cleaning vehicles, washing pets or playing with kids’ toys to help keep your lawn looking attractive!

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