Will Soapy Water Hurt the Good Worms?

Soapy water sprayed on plants can kill aphids, juvenile leafhoppers, beetles, and other pests. When poured on your lawn, soapy water can help you deal with a grubworm or armyworm infestation. But will soapy water hurt the good worms? 

Earthworms will try to get away from soapy water. If they can make their escape, they will be fine. You can use soapy water in moderation and suitable places as a pesticide-free way of controlling bad bugs without damaging your earthworm population.

This article will show you how and where to use soapy water to deal with unwanted insect infestations. It will teach you what types of liquid soap work for pest control. You will learn how to use soapy water to spray surface insects and flood out burrowing grubs.  

And you will be able to do this without worrying about the good worms! 

How Does Soapy Water Kill Pests?

While there are many theories, we still do not know precisely how soapy water kills insects. Soap may disrupt the insect’s cell membranes. Soap may remove the protective waxes from the insect’s body. Or it may suffocate insects by forming a film over their breathing pores. 

While it may not be clear how soapy water kills soft-bodied insects, we know it does. People have been using soapy water for pest control for over 200 years. Many of the soaps we use have changed, but our soapy pest control techniques have remained consistent.

How Do You Use Soapy Water Against Pests? 

Before you begin pest-fighting with soapy water, you must make sure you are using a suitable soap. Many things which today go by the name of soaps are not soaps at all.

Make Sure It’s Soap, Not Detergent!

When animal and vegetable fats became hard to come by during World Wars I and II, scientists developed synthetic detergents which behaved like soap. Detergents can be made more cheaply than soap and can be more easily tailored to specific conditions. 

Soap molecules surround tiny particles of dirt till they float in the wash water. They bond to oils and carry them away from your skin and clothes. Soap kills many viruses and bacteria by destroying the lipid (fatty) membrane that holds them together. 

Many detergents contain chemicals that can damage plants as well as pests. If you want to use soapy water, your best bet is an oil-based liquid soap like Dr. Bronner’s Pure Castile Liquid Soap that kills pests while keeping plants and earthworms safe.

Spray Soapy Water To Fight Pests on Leaves

You can use a ready-made spray like Garden Safe Insecticidal Soap, or you can make your own. Add two teaspoons of mild natural soap to a quart of water. 

If your tap water is hard (alkaline), you can use bottled water or add a squirt of lemon juice to bring the pH down. Soap is less effective in hard alkaline water. You can also add one or two teaspoons of neem oil like Milania Premium Organic Neem Oil for extra protection.   

What Is Neem Oil?

Neem oil doesn’t just kill aphids and soft-bodied insects. Its bitter garlic-sulfur smell discourages predators from eating your leaves, and its fungicidal qualities can help protect against black spot, sooty mold and rust

Oh, and did I mention that neem oil not only doesn’t hurt earthworms, but it’s also good for them?  

Put your soap, neem, and water solution into a spray bottle. Before you use this, spray a few leaves of each plant. This solution should not cause your plants any harm, but it’s always good to test any pesticide, even soapy water, before soaking your plants with a new substance.

Spray each infected plant thoroughly. Any soft-bodied insect that gets soaked is a goner. Aphids and leafhoppers will be gone along with their larvae. After this spray dries, no harmful residue remains.  

This means you will have to repeat this every week or every 3-4 days if you have a severe infestation of soft-bodied insects. This spray will also do little to discourage hard-bodied insect pests like Japanese beetles. They will run from the soapy water, but it will not kill or harm them. 

Check this article to know more about the benefits of neem oil!

Careful Where You Spray Soapy Water!

If you are in a warm area, or your plant gets lots of sun, spray in the afternoon. Spraying soapy water on plants can cause leaves to become more easily sunburned.  

According to the University of Florida, you should avoid spraying soapy water on the following plants: 

  • Bleeding Heart 
  • Crown of Thorns 
  • Delicate ferns 
  • Fuchsia 
  • Lilies
  • Plants with hairy leaves 
  • Sweetpeas 
  • Waxy succulents

Use Soapy Water To Fight Lawn Grubs and Armyworms

Lawn Grubs and Armyworms are two pests that do ugly damage to lawns, golf courses, and other green spaces. Soapy water can help you get rid of them.

The Root-Gnawing Lawn Grub

With their ugly orange heads and fat slimy bodies, lawn grubs look like something out of Alien. Grubs are the larval forms of several different beetles and eat grassroots like potato chips.  


If you are seeing brown patches in your lawn or noticing raccoons and other animals are rooting in those patches, you may have a lawn grub infestation. One good way to find out is to flush the ugly little creatures to the surface.

Mix up a gallon of the soapy water mix given above. Use three tablespoons of organic oil soap. You can add a tablespoon or two of neem oil if you like. Pour this in your most prominent brown patch. See how many slimy grubs pop their heads up as they try to get away from the flood.

The Grass-Gnawing Armyworm

Armyworms, moth caterpillars, can also cause brown patches in your lawn. But while grubs live beneath the soil, armyworms live at the lawn’s bottom and chew on grass blades.  

Armyworms leave distinctive square “empty windowpane” holes on the blades they chew. Their chewing kills individual blades and, in time, can destroy an entire thatch of grass. When soaked with soapy water, these nasty little creatures will try to climb away.  

The Innocent Earthworm

You will probably see a couple of earthworms breaking out of the soil. Don’t worry. They will be alright. Earthworms regularly come above ground when the ground gets saturated with water. That’s why you see them on sidewalks after rainstorms.  

worm farming

So long as the earthworms can get away from the water, they will be fine. Leave them to find drier land. Pick up any grubs or armyworms you find and dispose of them adequately.   

Put Dishwater (Not Soapy) on Your Flower Beds

Most dish soaps today contain antibacterial agents. You should never water flower beds with soapy water, especially if you used dishwashing detergent. But if you first soak your dishes in a basin of plain water, that dirty water will give your soil a healthy serving of bacteria food.

Plants need bacteria. Bacteria break down organic molecules in the soil, making nutrients more available to your flowers. The more food the good bacteria get, the happier your flowers will be. And your earthworms will happily eat the food floating in this “greywater.”  

Happy earthworms are good for your flowers and the good bacteria. Thriving earthworm colonies increase the numbers of good bacteria and lower the numbers of harmful bacteria that can attack your plants’ roots. 

Don’t overwater your plants. A little greywater goes a long way. This dirty dishwater is a fertilizer and, like all fertilizers, should be used sparingly. 

Greywater Is for Flowers, Not Vegetables

This trick should be used in your flower bed, not your vegetable gardens. In the ground, worms and bacteria consume the food particles. If that water winds up on your tomatoes or cabbages, those food particles could rot.  

You wouldn’t eat rotten food. And you don’t want to eat the bacteria that cause food to rot. Greywater can help your decorative plants grow, but avoid using it on food plants.  

Final Thoughts

Now you know how to use soapy water in your garden, and you don’t have to worry about hurting the good worms while you do it! Here’s to happy, pest-free gardens and fat, healthy earthworms

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Anat Goldberg

Hi! My name is Anat and I have lived all my life in the countryside. I grew on a farm in Northern Italy and from an early age, I took care of the animals on the farm and the family garden. Over the years I have developed a growing passion for organic cultivation and pest control.

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