Insecticidal Soap Is Our Favorite Solution to Common Plant Pests

updated May 3, 2019
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(Image credit: Brittany Purlee)

Have you ever peeled back the leaves on a bunch of homegrown kale to discover hundreds of scaly little bugs? Those are aphids and the sight of them will make you throw away your kale and order pizza instead. And anyone who’s had a houseplant infested with spider mites will have been tempted to chuck said plant, pot and all, straight out the window. The damage they cause can eventually kill the plant, and the mites spread quickly. If you have one houseplant that has mites, it’s only a matter of time before all of your plants have mites. But before you throw open the window or fire up the garbage disposal, there’s one easy solution you should try first: insecticidal soap.

What is Insecticidal Soap?

Insecticidal soap is a non-toxic spray that kills small soft-bodied insects (like spider mites, aphids, whiteflies, and mealybugs) that are notorious for decimating foliage and churning the stomachs of gardeners everywhere. The oily soap penetrates the soft outer cell membranes of the insects, causing them to suffocate.

Insecticidal soap can be used both outdoors and indoors and it won’t negatively affect beneficial insects or other wildlife. It’s cheap to buy, and even cheaper if you make your own. If you want to purchase it, look for a product like Garden Safe Insecticidal Soap Insect Killer or Epsoma Organic Insect Soap.

(Image credit: Amazon)

Espoma Organic Earth-Tone Insecticidal Soap – 24 oz Spray from Amazon; $14.41 with free shipping

DIY Insecticidal Soap Recipe

You can mix up your own insecticidal soap with three ingredients you probably already have in your house: vegetable oil, liquid dish soap or castile soap, and water. You’ll also need a spray bottle. (If using dish soap, make sure it doesn’t contain bleach or degreaser, and avoid synthetic dyes and fragrances if you can).

Add a quarter cup of vegetable oil and one tablespoon of the liquid soap to the spray bottle. Fill the rest of the bottle with warm water and shake it really well. That’s it!

How to Use Insecticidal Soap

Whether you’re using a commercial or homemade insecticidal soap, the application is the same. Spray the solution directly on the pests, making sure they are thoroughly wet. Do this weekly until the pest problem is resolved.

For outdoor plants, apply the soap in the early morning or evening to prevent it from drying up in the hot afternoon sun and to keep the plants’ leaves from burning. Some plants will be more sensitive to insecticidal soap than others, so it’s always a good idea to test it out on a small portion of the plant to see how it reacts before spaying it all over.