If you’re looking for an eco-friendly and cost-effective way to combat plant pests, you can make it yourself at home. Homemade insecticidal soap is a powerful but gentle solution for protecting plants from common garden invaders. This simple mixture can be just as effective as store-bought pesticides without the harsh chemicals. Here’s a DIY guide to making and using homemade insecticidal soap for a natural alternative to keep your plants healthy and pest-free.

What Is Insecticidal Soap?

Insecticidal soap is a type of pesticide that uses the fatty acids in soap to target and eliminate soft-bodied insects. Unlike chemical pesticides, insecticidal soap is biodegradable and generally safe for humans and pets when used as directed. It works by breaking down the protective outer layer of insects, causing them to dehydrate and die.

Insecticidal soap is a contact insecticide, meaning it must directly touch the pest to be effective. When you spray it on insects, the soap disrupts their cell membranes, causing them to lose water and eventually die. This method is particularly effective against soft-bodied insects like aphids, mealybugs, and spider mites.

It’s important to understand that insecticidal soap and dish soap are not the same, even though they both contain soap. Commercial insecticidal soaps are specifically formulated for use on plants and pests. Dish soaps often contain additives that can harm plants. However, pure liquid soaps like Castile soap can be used to make a homemade version that’s safe for most plants.

Insecticidal Soap Recipe

Making insecticidal soap at home is a simple process that requires just a few ingredients. This DIY solution is cost-effective and makes it easy to control exactly what goes into your pest control products.

To craft this effective pest deterrent, you’ll need some common household items:

  • 1 to 2 tablespoons of pure liquid soap (such as Castile soap)
  • 1 quart of water
  • A clean spray bottle or garden sprayer
  • Optional: 1 to 2 tablespoons of vegetable oil (for pest control enhancement)

Start by filling a clean spray bottle or garden sprayer with 1 quart of water. Add 1 to 2 tablespoons of pure liquid soap to the water, then add 1 to 2 tablespoons of vegetable oil to help the solution stick to plants longer. Gently shake or stir the mixture to combine all ingredients. To finish, test the solution on a small area of the plant before applying it more broadly.

    How To Apply Homemade Insecticidal Soap

    After making your soap, the next step is to properly apply it. Use careful timing and technique, making sure the treatment reaches every nook and cranny of the plant, where pests like to hide.

    Apply the solution in the early morning or late evening to prevent leaf burn. Thoroughly spray both the tops and undersides of leaves, where pests often hide. Plan to reapply the soap every four to seven days or after rain until the pest infestation is under control. Avoid spraying in direct sunlight or when temperatures exceed 90°F (32°C), and don’t apply it to drought-stressed plants or those with sensitivity to soaps.

    What Insects Are Affected by Insecticidal Soap?

    Homemade insecticidal soap is particularly effective against soft-bodied garden pests. Its targeted approach helps balance beneficial insects in the garden while controlling problematic ones. Some of the soft-bodied insects it can help eliminate are aphids, mealybugs, whiteflies, spider mites, thrips, scale insects (in the crawler stage), and psyllids. On the other hand, it’s much less effective against beetles, caterpillars, and grasshoppers.

    Recipe Variations and Alternatives

    While the basic recipe is effective, there are plenty of ways to tweak the standard recipe to better suit specific plant needs or environmental conditions.

    For sensitive plants, make a diluted, 1% solution by using 1 tablespoon of soap per quart of water. This lighter mixture is gentler on plants but may be slightly less effective against pests.

    You can also try an oil-enhanced spray. Add 2 tablespoons of light cooking oil (such as corn, canola, or olive oil) per gallon of the soap mixture. This helps the solution stick to plants longer, potentially improving its effectiveness. If your plants suffer from mildew, add 1 teaspoon of apple cider vinegar per gallon of the soap solution to target powdery mildew along with insects.

    For added protection against chewing insects, mix in 1 teaspoon of ground red pepper or minced garlic per gallon of soap spray.

    Precautions for Using Insecticidal Soaps

    Using homemade insecticidal soap is an easy way to keep pests off your plants, but you should also take certain precautions to protect your plants and beneficial insects.

    • Always test the solution on a small area of the plant first and wait 24 hours to check for any adverse reactions.
    • Avoid spraying flowering plants to prevent harming pollinators.
    • Don’t apply to plants with hairy leaves, as they tend to hold onto the soap which can be damaging.
    • Rinse plants with clean water a few hours after application to prevent leaf damage.
    • Store the solution in a clearly labeled container out of reach of children and pets.

    Frequently Asked Questions

    Is homemade insecticidal soap safe for all plants?

    Homemade insecticidal soap isn’t safe for all household plants, as some are sensitive to it. That’s why we recommend testing it on a small area of your plant first. Then, wait a day or two to see how it reacts.


    How often should I apply homemade insecticidal soap?

    I recommend applying it every four to seven days or after rain until your pest problem is under control.


    Can I use dish soap to make insecticidal soap?

    No, you should only use pure, natural soaps like Castile soap to avoid harming your plants.


    Will homemade insecticidal soap kill beneficial insects?

    Homemade insecticidal soap can harm beneficial insects on contact, so apply carefully and only where your plants need it.


    Editorial Contributors
    photo of Jonathon Jachura

    Jonathon Jachura

    Contributor

    Jonathon Jachura is a two-time homeowner with hands-on experience with HVAC, gutters, plumbing, lawn care, pest control, and other aspects of owning a home. He is passionate about home maintenance and finding the best services. His main goal is to educate others with crisp, concise descriptions that any homeowner can use. Jon uses his strong technical background to create engaging, easy-to-read, and informative guides. He does most of his home and lawn projects himself but hires professional companies for the “big things.” He knows what goes into finding the best service providers and contractors. Jon studied mechanical engineering at Purdue University in Indiana and worked in the HVAC industry for 12 years. Between his various home improvement projects, he enjoys the outdoors, a good cup of coffee, and spending time with his family.

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