DIY Aphid Spray Recipe: How to Make Homemade Insecticidal Soap
Are aphids, mealybugs, or other pest insects wreaking havoc on your garden? Come learn how to make DIY aphid spray to get rid of them with this simple homemade insecticidal soap recipe. It’s effective, inexpensive, and easy to make! This post also covers important application tips for the best results.
When mixed and used correctly, homemade insecticidal soap is effective at killing small soft-bodied insects. On the other hand, it’s gentle on your plants, non-toxic to wildlife, and does not harm beneficial insects like ladybugs or bees. Made with natural castile soap, that means this DIY aphid spray recipe is safe for organic gardening. Insecticidal soap can also be used indoors on houseplants.
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RELATED: Get even more organic aphid control tips here, or learn how to get rid of cabbage worms and control grubs in the garden here.
Remember that a garden isn’t supposed to be perfect or free of insects! Above all, we want to encourage a balanced and healthy ecosystem. Following organic gardening practices and companion planting will encourage beneficial insects that naturally pray on aphids, such as ladybugs and green lacewings. I don’t worry when I see a few aphids here and there. Yet when their population gets out of hand, I make a batch of homemade aphid spray.
What Is Insecticidal Soap?
Insecticidal soap, also known as horticultural soap, is a spray used to control small soft-bodied pest insects on plants. It is effective against aphids, mealybugs, spider mites, white flies, psyllids, and scale.
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 my own. It’s far cheaper, and about as non-toxic and natural as you can get!
How does it work?
Insecticidal soap works by disrupting soft-bodied insect’s 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 via pest-specific physical means, not by “poisoning” them.
That means soap spray is NOT effective against insects that have a hard exoskeleton or different anatomy – such as most beetles, ladybugs, crickets, bees, grasshoppers, pill bugs, grubs, or even caterpillars.
Furthermore, homemade insecticidal soap has little-to-no residual effect, and only kills instantly on direct contact. This means that it must be sprayed right onto the target pests to work.
DIY Insecticidal Soap Recipe
You only need two ingredients to make DIY aphid spray: liquid soap and water. Pure natural castile soap is the best choice for homemade insecticidal soap: it’s 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 the peppermint aroma deters pests too!
Some old-school gardeners like to use Dawn dish soap, but it has a lot of other ingredients that I personally don’t want on my plants (or to eat). 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 castile 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, you can mix the soap spray in a classic trigger spray bottle. To treat a larger plant or area, we use my favorite half-gallon pressure sprayer. It holds more spray AND is way easier on my hands! 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 new plant treatment, it’s 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’s best to apply insecticidal soap in the evening. Do not apply soap spray in direct sunlight, as it can sunburn plant leaves – known as phototoxicity. Beneficial insects are also 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 often use my hands to rub the infected areas and leaves as I spray, manually squishing the aphids or mealybugs with my fingers at the same time.
- Let the insecticidal soap soak on the plants for at least 30 minutes.
- Now, you don’t have to rinse off the soap spray after, but I usually like to. It removes soapy residue on your plant leaves, reduces the risk of discoloration, and also washes off the now-dead bugs. Gently spray the plant off with water to rinse (but again, avoid wetting leaves during sunny conditions).
- 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!
And it’s as simple as that.
I told you it was easy to make homemade aphid spray! Now you can safely battle the pests in your garden in an effective, non-toxic and environmentally-friendly way. I hope you found this article to be helpful. Please feel free to ask questions, or spread the love by sharing this post. May your plants be happy, healthy, and mostly pest-free!
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
- Non-Toxic Gopher Control: How to Gopher-Proof Your Garden
- How to Prevent and Treat Powdery Mildew Organically
- How to Identify the Top 18 Garden Pests, and Beneficial Insects
- Over 25 Ways to Stop Pests From Destroying Your Garden
71 Comments
Chris
Will this organic spray harm spiders. I do not want to harm the spiders on my plants in my pollinator garden. Sorry, I’ve asked this question before but couldn’t remember the article and couldn’t find your answer. Thanks!
Aaron (Mr. DeannaCat)
Hello Chris, I responded to your question but it was on the other aphid control article (haha). Anyway, here was my response: Hi Christine, thank you so much for the kind words and support. I am unsure if it kills spiders but when using the soap spray it is good to only spray on the target areas as to not spray any non target insects that may be around. Usually spiders will leave an area once they notice movement that is larger than they care to deal with. Hope that helps and good luck!
Kathy
None of the articles I found elsewhere on the internet had soap recipes or instructions that explicitly confirmed their recipes would not harm beneficial insects/lady bugs. Then I found this article. Yay! We used the soap recipe with the solo pump sprayer and are happy to know this concoction will rid the tomatoes and roses from aphids. My hand and joints thank you for the tip on the solo pump sprayer, that thing is solid and wish I’d purchased it sooner. Thank you for the great content.
Aaron (Mr. DeannaCat)
Hi Kathy, we’re so glad it’s working well for you and thanks for your support!
Silvia Fernandez
So I didn’t read the whole posting before applying this insectiside. Should I rinse the plant and apply it tonight? I have a question in regards to leftover liquid. Do I throw it away or how long can it be kept?
Aaron (Mr. DeannaCat)
Hello Silvia, we usually store whatever leftover soap mixture we have in the sprayer and save it for later use. It is best to apply the soap spray at night but we have also used it during the day with little to no negative effect on the plant. However, we will rinse it the day or two after, especially if the treated plants were leafy green vegetables that we intend to eat. Hope that helps and good luck!
Christine Belker
I just subscribed to Homestead & Chill. I’ll have to say it is the most informative website I’ve ever visited. You are so very thorough about everything! What a wealth of information!
Thanks,
Christine B
Aaron (Mr. DeannaCat)
Thank you so much for the kind words and the support!
Beverly
Planted my first monarch/pollinator garden last spring. Joy of the garden & incredible monarchs really kept me sane during Covid year. But aphids!!! Milkweed looked like it had orange stems. I tried spraying with water and squishing (cried when I squished a wee monarch caterpillar). Horrid, endless battle! Loved this article. Will use Castile soap as you directed. Been growing roses for many years. Do you have any specific advice for environmentally friendly maintenance of roses?
Aaron (Mr. DeannaCat)
Hello Beverly, glad to hear you have made monarchs a priority and that they helped you just as much as you helped them! Aphids do love milkweed so using soap spray and blasts of water works best. We haven’t actually grown roses at all so we don’t have much to offer as far as they are concerned. I would try using the soap spray or using a neem oil foliar spray for pest prevention, although I wouldn’t spray the neem foliar on your roses once the flowers have emerged unless absolutely necessary. Hope that helps and good luck! Keep us up to date on your progress.
Philip Treacy
Hi
Just tried the pure Castile soap & water spray on the malus contessa de Paris tree. Looks like the ants that were on security for aphids seemed to be dying also . Is that normal.?
Aaron (Mr. DeannaCat)
Hi Philip, yes it will harm the ants as they are a softer bodied insect which is the main target for soap based sprays. The ants are farming the aphids for “honeydew” which is what the aphids secrete for the ants and it makes it more difficult to rid your plants of either when they are working together. Good luck!
Rose
Hello, i have a question do you rinse off the Soap the nextday or just leave it as it is. Thank you
DeannaCat
Hi Rose, I usually like to rinse if off. You don’t absolutely have to, but that is what we prefer to do. Thanks for reading!
Aly Cardenas
Hi!!
Love your blog so much, thanks for all that you share! I have a question regarding clovers! They’re invading my raised bed and I swear every time I pull 5, 10 more pop up to replace it! Can they coexist with my garden or do I need to intervene and spray or what do you recommend??
Aaron (Mr. DeannaCat)
Hi Aly, clover is one that is really hard to get rid of but it seems to only pop up during certain times of the year and is quite easy to pull up by the roots as needed. I would not recommend spraying anything on them, just keep up with your weeding and if you pull them before they go to seed, there will be less in numbers as time goes by.
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?
Diane
I have a bottle of Dr. Jacobs Pure Castile peppermint soap and no do not use, you will kill your garden & fruit trees. Its not the same as Dr. Bronner’s peppermint soap that we have used.
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.
Keiko
Hi! Could I spray this directly on the roots when repotting? I found some pests and I decided to completely repot my plants and before I repot, maybe spray on the roots with some soil that wont come off the roots? Thank you.
Aaron (Mr. DeannaCat)
Hello Keiko, you could try and spray the roots with the soap spray since it is fairly benign and it shouldn’t have too much of a negative effect on your plants although we have yet to try this and usually focus the spray on the parts of the plants we can see. Good luck!
Stephanie
Hello!
Is this spay safe to use on herbs? I have whiteflies attacking my sage and mint and am hesitant to use anything “off the shelf” even when labeled for organic gardening.
Aaron (Mr. DeannaCat)
Hi Stephanie, yes this spray is safe to use on herbs, it is actually fairly gentle on the plants. This spray works best with direct contact on the pest so you will want to be sure to make contact with the white flies as they try to fly off. After a day or so after using the spray, spray the herbs off with plain water to get the soap residue off. Hope that helps and good luck!
Jennie
Hi there! Thank you for the info! Will this also work on the pesky little white fluffy pests I get on my succulents?
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!