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Beginner Basics,  Indoor Gardening,  Pests

Homemade Organic Garden Soap Spray Recipe: Kill Aphids & Other Pest Insects

Are aphids, mealybugs, or other pesky little insects making themselves at home in your garden? Don’t let them get too comfortable! Try using this mild, inexpensive, organic homemade soap spray to stop them in their tracks, and prevent them from further damaging your plants. Insecticidal soap spray can also be used indoors on houseplants. Read along to learn how easy it is to make your own!

When mixed and used correctly, an application of insecticidal soap is very effective at killing small soft-bodied pest insects like aphids, mealybugs, spider mites, white flies, psyllids, and scale. On the other hand, it is also gentle on your plants, non-toxic to wildlife, and does not harm beneficial insects like ladybugs, lacewings or bees!

Keep in mind that seeing a couple of bugs here and there is totally normal and even expected in an organic garden. When there are just a handful of aphids or other pests around, we generally do not intervene. Instead, we hope that that their natural predators like ladybugs or lacewings will help keep their population in check. We also buy and release ladybugs to help with that! But when it is apparent the “bad guys” are significantly outnumbering the good? Soap spray to the rescue! 


Disclosure: This post contains some affiliate links to products for your convenience, such as to items on Amazon. I gain a small commission from purchases made through those links, at no additional cost to you.

A close up image of a cluster of mealybugs that are piled on top of each other on a stem of a plant.They are lightish pink in color and there are a few ants visible while in the background, a green vine and the top of an agave plant are shown.
A cluster of mealybugs, just asking for it.


What Is Insecticidal Soap, & How Does It Work?


Insecticidal soap, also known as horticultural soap, works to kill soft-bodied insects by disrupting their sensitive cell membrane. Essentially, it coats and penetrates the natural protective barrier around their body, which causes them to desiccate – or dry out. It kills them by pest-specific physical means, and is not “poisoning” them. Thus, soap sprays are NOT effective against insects that have a hard exoskeleton or different anatomy – such as most beetles, crickets, bees, grasshoppers, pill bugs, grubs, or even caterpillars.

Furthermore, insect soap spray has little-to-no residual effect, and only kills on direct contact. This means that it must be sprayed right on to the target pests to work.

There are many commercially pre-made insecticidal soaps available to buy. However, while those are typically rated for “organic gardening” and are more environmentally-friendly than most other pesticides, they often still include a long list of chemical ingredients. Therefore, I feel much more comfortable making our own! I mean, why not? Homemade insecticidal soap is extremely cheap and easy to make, and is just about as natural and gentle as you can get. 


A spray bottle of soap spray sitting next to a bottle of Dr. Bronner's peppermint pure castile soap. Fence boards from a horizontal fence is the back drop.



INSECT SOAP SPRAY RECIPE


To create your own homemade insect soap spray, you only need two ingredients: liquid soap and water. Pure castile soap is the best choice for making soap spray. It is effective and won’t harm your plants. We use Dr. Bronner’s liquid castile soap. Peppermint Dr. Bronner’s soap provides a further line of defense, since peppermint deters pests! Avoid using soaps or detergents with bleach or degreaser additives, or those intended for the dishwashing machine. 


Mixing Instructions:

  • Simply combine 1 tablespoon of liquid soap per quart of water. Mix only what you will use that day.
  • For a larger batch, use 5 to 6 tablespoons of soap per gallon of water.
  • Shake together in your sprayer to thoroughly mix. Use warm water to promote mixing.
  • For light applications, mix them in a small classic spray bottle. To treat a larger plant or area, we use a half-gallon pump sprayer – to create more soap spray, and also reduce the need to repeatedly squeeze a “trigger” during application. If you re-use old cleaning spray bottles, make sure to thoroughly wash them out before using them in your garden!


A two part image collage, the first image shows a hand holding a spray bottle of soap spray pointing towards a milkweed plant that is covered in orange aphids. The second image shows a close up of the aphids after they were sprayed with the soap spray. The aphids and part of the plant are covered in a foamy soap residue.
Milkweed always attracts a ton of yellow aphids! I often simply blast them off with water, but that doesn’t necessarily kill them – it just washes them away. Soap will do the trick. Note that there are many colors and types of aphids, including yellow, black, grey, green, and white!



Application Instructions:

  • As with any plant treatment or spray, it is “best practice” to apply it to a small test area a day or two before treating a larger area. Honestly, we’ve never had issues with soap spray – but I have to give you the disclaimer!
  • It is best to apply soap spray in the evening. Do not apply spray in direct sunlight, as it can sunburn plant leaves – known as phototoxicity. Additionally, beneficial insects are less active during evening hours!
  • Insect soap spray only kills on direct contact, so spray it right on the pests! Coat them thoroughly.
  • Turn over or peel open curled-up leaves as needed to access hard-to-reach bugs. I usually get all up in there and rub the infected areas and leaves as I spray, manually squishing the aphids or mealybugs with my fingers at the same time.
  • If it is forecasted to be very hot and sunny the day after your evening application, I suggest rinsing off the residual soap (and now – dead bugs) by spraying the plant with water by the next morning. Again, this is mostly to prevent potential sunburn, though I like the satisfaction of cleaning up and spraying away the victims too! Avoid wetting leaves during direct sunlight hours.
  • Re-apply soap spray every 4 to 7 days as needed. It may take several treatments to solve the pest problem.
  • Treat early. It is much easier to nip a little infestation in the bud than wait and battle an epic one!


Still have pests on your plants?

For persistent problems, insecticidal soap spray treatments can be used in conjunction with neem oil for further pest prevention. Neem oil repels most small pest insects, and also prevents fungal diseases like powdery mildew. It is very popular in organic gardening, but also frequently used incorrectly. Therefore, read this article to learn how to properly mix and use neem oil!

If you’re frustrated and struggling with pests, try not to stress! It is a normal part of organic gardening. Your garden shouldn’t be devoid of all life, nor your plants completely pest-free! That simply isn’t natural. Yet with some good tips and tools under your belt, you should be able to keep them to a manageable level.

For more tips on organic pest control, be sure to check out our other related articles:


A three part image collage, the first image shows a hand holding a leaf of an artichoke plant while spraying the underside of the leaf with a hand sprayer. The second image shows a crease in the underside of the leaf after it has been sprayed. The black aphids are visible along the crease where they were residing. The third image shows the hand held pump sprayer spraying the whole artichoke plant. The stream from the spray is visible and there are various plants and shrubs in the background.
Applying soap spray to aphids on an artichoke plant, using a larger 1/2 gallon sprayer. As you can see, I am making sure to get in all the cracks and crevices, and am also rubbing and smashing the aphids at the same time.


And it’s as simple as that!


I told you that making your own organic soap spray is easy! Now you can safely battle the pests in your garden in an effective, non-toxic and environmentally-friendly way.


In all, I hope you found this article helpful and interesting! Please feel free to ask questions, or spread the love by sharing this post. May your plants be happy, healthy, and mostly pest-free!



DeannaCat's signature, Keep on Growing

8 Comments

  • Dave

    I am planning to use Castile soap to treat insects in my vegetable garden. I purchased a 10 oz bottle of Dr. Jacobs Pure Castile Peppermint foaming hand soap. Is this the correct soap to safely use in my garden, and if so, do you have any recommendations on how to mix it properly?

    • DeannaCat

      Hi Dave, that soap sound similar to the castile soap we use… except for the “foaming” part. Is it just the pump that makes it foam? If so, unscrew the top and then use it as directed in this article. But it there are a bunch of other ingredients in it (aside from pure castile soap) then it is not the same of what we use or recommend.

      • Dave

        Thanks for the quick reply. I checked the bottle of Dr. Jacobs Pure Castile Peppermint foaming hand soap, and ingredients include water, coconut oil, sunflower seed oil, potassium hydroxide , glycerin, peppermint oil, citric acid, and vitamin E. Are they the same ingredients as the Dr. Bronner’s you recommend for use? If not, do you think I would be safe to use this type on my garden plants?

  • Susan

    Love your blog, tons of information.
    When I tackle the aphids I fill a plastic food storage container (8” diameter) with the soapy water, I bend down the tip of the plant stem that’s loaded with the aphids and let them soak for 10 seconds. I do all effected areas on the plant then I go back using clean water and Swish the stems around in the water and ALL those nasty aphids come floating off.

  • Andreea

    Hello, can I use this solution on plants with edible roots? Will the soap remain in the soil and then be absorbed by the root?

    • DeannaCat

      Hi Andreea. Hmmm… I haven’t really thought about that before. What kind of roots? I think if you applied the soap lightly and weren’t planning to harvest the roots in the immediate future (meaning, they’d get plenty of water/washing away the soap for the next month or so) I can’t imagine it leaving a residue or being absorbed.

    • DeannaCat

      Hi there! Yes, those are most likely mealybugs! You can definitely use soap spray for those. Another option, if there aren’t too many of them, is to dip a Q-tip in rubbing alcohol and swap each of them with it. It kills them in the same manner. Good luck!

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