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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

49 Comments

  • Sharon

    I am getting slammed this year in our new house. And it is like overnight it is fine and then covered with army worms that BT is barley touching on the Swiss chard. Then today all my kale is white with white flys. So hard to wash off. I am going to try the bronners soap. But am thinking because I have so many winter greens growing about using neem. Plus that bed has given me some problems with mildew. Will that help prevent it? And the bottle you recommend is pretty big. Does the neem spoil?
    You guys have been so helpful thank you and o love seeing the pictures of my home area. Thank you.

    • Aaron (Mr. DeannaCat)

      Hi Sharon, that is too bad you are getting hit with so many pests at once. The neem will last for at least a year and I would only use it on the greens if you plan on not eating any of the greens for a couple weeks. We don’t have to deal with army worms but BT should be able to take care of them, I would apply BT at least once a week to keep them under control, apply it at night or just before the sun goes down as sunlight can make the effective portion of BT dissipate more quickly. Also, as far as your white fly issue goes, I would first just stick with the soap spray and see how that goes. Apply it a couple times a week if the white flies are still sticking around. You can always rinse off your greens on the days in between soap sprays if there is excess on the plants as it should take care of the flies on contact and doesn’t off much after that. I would stick with the two options that were just mentioned before treating the plants with neem oil although we have found that it seems to help prevent mildew. Hope that helps and good luck, let us know if anything else comes up.

      • Sharon

        Help! I have used the spray for the white flys and it is helping on the kale. But they are covered in eggs. The kale still looks perfect to eat but how does one get those eggs off? I tried to soak in salt. Vinager and also some castle soap. This little eggs are so attached especially to the curly kale. I hate to waste all my plants. Any ideas??? It is literally every inch covered in eggs.

        • Aaron (Mr. DeannaCat)

          Hi Sharon, guess those cabbage white butterflies have been busy! Can you brush the eggs off with a sponge or even using your hands? If you continue to treat your kale with BT the number of eggs and caterpillars will slowly diminish with time. As it gets colder the butterflies will slow down and it won’t be as much of an issue for you.

  • Renae Mattson

    Hello! I have an aphid infection on my milkweed plants. I see in the article that this soap won’t hurt caterpillars, but I have some teeny tiny ones and want to make sure the soap is safe for 1st and 2nd instar cats. Thanks, Renae

    • Aaron (Mr. DeannaCat)

      Hi Renae, the caterpillars will be just fine, you can rinse it the plant off afterwards with water which can knock off the dead aphids while rinsing the caterpillars as well. Just try and be as direct as you can with the spray to only spray your target (aphids). Hope that helps and good luck!

  • Kathie

    I have Castile soap, but my husband saw a recipe that also called for orange oil. I’m reluctant as can’t find the site. Is it okay to add it to insecticidal soap or not? If so, how much should I add?

    • Aaron (Mr. DeannaCat)

      Hi Kathie, you can add different essential oils to your pest or preventative sprays to help repel pests. Our neem oil spray does include some optional essential oil additions such as peppermint, lavender, orange, tea tree, or eucalyptus among others. 10-20 drops per gallon of spray should be a good amount to use, though I would start on the lower end to begin with. Hope that helps and good luck!

  • Gwen Cook

    What do you recommend to kill ants on plants? I have tons of them in my garden. Especially on my artichokes.

    • Aaron (Mr. DeannaCat)

      Hi Cindy, the most common methods are hand picking them early in the morning when they are most active or using pest sprays such as a soap spray to spray directly on the beetles or neem oil spray on the plants themselves as a preventative measure. You can also treat your soil with beneficial nematodes which will attack the beetle larva before they turn into adult beetles which should reduce your beetle population. Just be sure to select the correct nematodes that will work for Japanese beetles. We have used beneficial nematodes to combat curl grubs and it worked very well. Check out our article on How to Kill Grubs & Garden Soil Pests Organically w/ Beneficial Nematodes. Hope that helps and good luck with your zinnias, they are a beautiful flower and one of our favorites!

  • Hank Cowdog

    Since you can brush your teeth with Dr Bronners, any tiny amount left on the plant after a washing and/or a couple of rains should not be a problem.

    • Shawn E

      Hank, Yes on the bar soap. That’s what I use. NO on the liquid. But Dr Bronners bar soap is a wonderful tooth cleaner. No Glycerin to encourage bacteria! wonderful clean. less staining from coffee. I’ll never go back to toothpaste.

  • Deb A

    Love all this info!! Question about using Dr. Bonner’s – what about eating after spraying with this soap – sage, for example. Will rinsing be enough to eliminate the soap or is it absorbed by the leaves?

      • Tracy

        Hi, I just have a slight concern over the Palm Kernel ingredient listed on the Dr Bonners soap – I can’t find any info as to its source, if it’s sustainable or not. Any ideas please?

        • Aaron (Mr. DeannaCat)

          Hey Tracy, check out this FAQ or a press release that Dr. Bronner’s put out about it. You will have to decide if it’s something you want to support or if there are other alternatives, yet most other brands of soap ingredients include items that are hard to pronounce and I would have to look up to even know what exactly they are. Hope that helps and good luck!

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