Dish soap can be harmful to plants because it strips them of their natural oils, causing them to shrivel up and die. Although a mixture containing dish soap can be effective in killing insects and certain weeds on your lawn, it also damages your grass. So, despite the many gardening hacks involving dish soap, this is not a recommended practice.
What Does Dish Soap Do for Your Lawn?
The idea behind spraying dish soap on your lawn comes from the fact that it can kill insects and even certain weeds. In other words, it acts like a DIY pesticide. There are excellent herbicides out there, great for weeds on your lawn, we’ve reviewed Tenacity here and we couldn’t recommend it enough.
The chemicals in dish soap remove oils which is great for your dishes but not for plants. It also kills insects by drying them out, causing their exoskeleton to separate from the rest of their body.
However, the potential damage that it has on your lawn is not worth it. Dish soap is not selective – it dries up everything that comes into contact, including your grass.
Can You Use Dish Soap on Your Lawn Safely?
Does dish soap kill grass? No, although it might still do some damage, there is a way to use dish soap as an insecticide with less impact on your lawn. To do this, you need a very diluted mixture of water, vegetable oil and dish soap.
How to Spray Your Yard With Dish Soap
Combine cup of water with equal parts of dish soap and vegetable oil. Just a teaspoon of the last two ingredients is enough.
Fill a spray bottle (we recommend this one from amazon) with the mixture and start spraying the parts of your lawn affected by insects and weeds. The pests must come into direct contact with the mixture to die so this is not a precise science when it comes to dealing with insects.
After a few hours, hose down your lawn making sure that none of the mixture remains. This is a very important step – if you don’t wet your lawn enough the grass will shrivel up, too.
Insecticidal Soap vs Dish Washing Detergent
There is a safer alternative to dish soap: insecticidal soap. To understand why this is a better alternative you need to understand what is inside each.
Dish soap actually isn’t a soap. Dish soap is better described as a dish washing detergent rather than a soap.
A soap is made of natural oils or fat mixed with sodium hydroxide or a different kind of alkali. This part is natural but most store-bought soaps also contain added coloring and scents.
Detergents consist of surfactants, these are chemicals (natural or manufactured) that break down the molecules of oils and dirt so that it becomes water soluble. Detergents also tend to have extra ingredients to make the foaming reaction as well as coloring and scents.
These surfactants are what has the dangerous effect on your lawn. Since there are no surfactants in a soap, you won’t have the same issue.
You can buy insecticidal soap, a mixture containing soap salts specifically for horticultural use. These formulas do not strip the plants from their natural oils but they do kill insects.
Insecticidal soap is a much safer and organic choice for ridding your lawn of pests. Most formulas are even safe for other animals, including the endangered bee.
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Frequently Asked Questions:
Will Dish Soap Kill Lawn Fungus?
Dish soap, or dish washing detergent rather, will dry out lawn fungus, much like how it reacts with other plants. You can create a light solution of water and dish soap and use it as a spot treatment to kill lawn fungus.
Make sure that you get the solution only on the fungus itself because it will have the same effect on your grass. Remember that it is a spot treatment, not something you should spread over your entire lawn.
Does Dish Soap Kill Grubs?
Yes, dish soap can kill the average garden grub. The solution essentially smothers them but it is only effective if they are completely covered by the liquid. Although you might be able to kill some of the grubs in your yard with a DIY solution containing dish soap, it won’t kill them all.
Does Dishwashing Liquid Help Grass Grow?
Dishwashing liquid does not help grass grow. This is an urban myth. Dish soap contains surfactants which will dry out and kill grass.
Will dawn dish soap kill grass?
Does dawn dish soap kill grass? No, Dawn dish soap will not kill grass. However, it can harm plants if used in too high of a concentration, so it is best to use it sparingly on lawns.
Although dish soap sounds attractive as an affordable DIY hack, it is not recommended. Most dish soaps will not only kill insects and weeds but also the grass itself. Insecticidal soap is a much safer alternative.