Homemade Organic Pest Soap Spray Recipe: Kill Aphids, Mealybugs & More

Last Updated on August 30, 2023

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.

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. 

INSECT SOAP SPRAY RECIPE

To create your own homemade aphid 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 aphid 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!

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 aphid 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:

• How to Properly Emulsify Neem Oil & Make a Safe Garden Pest Spray
• How to Prevent and Treat Powdery Mildew Organically
• Organic Pest Control, Part 1: How to Prevent Pests in the Garden
• How to Identify the Top 18 Garden Pests, and Beneficial Insects
• Over 25 Ways to Stop Pests From Destroying Your Garden
• Organic Cannabis Pest Control: How to Keep the Bugs Off Your Nugs

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!