DIY Insecticidal Soap

By Ashley Chesser, Communications & Development Director

I proudly survey the messy kaleidoscope of green hues before me. By the end of June, as sunlight clings to the final hours of each day, the fruits (or veggies!) of my labor finally manifest as more than stubborn remnants of dirt underneath my fingernails. Kale and chard are nearly ready for a stir fry, and the lettuce and spinach have started participating in salads. My two young daughters devour raspberries daily.

I am grateful for this patch of earth where my family is able to live and play, and pause to pay respect to the Kalapuya peoples who call this their homeland. I also think of the struggling pollinators, the neighborhood cats who pay no mind to fences and the salmon at the path's end of the city water runoff. For these reasons and more, I refuse to spray synthetic chemicals in my garden or yard.

(My oldest daughter, Silvia, picking raspberries in our front yard.)

But that doesn't mean pests have free reign here. I tolerate their existence as part of the ecosystem, and work to create balance. Pollinator and beneficial insect attracting flowers inhabit prime real estate in my yard. I sprinkle clover seeds each fall in my small bit of lawn and use beer traps when the slugs are too abundant. When soft bodied insects get out of balance, like a swarm of aphids on my kale, I use an insecticidal soap. I always have some on hand, because – mom tip – it doubles as an excellent all-purpose cleaner for kid spills around the house.

Insecticidal soaps work by disrupting the cell membranes and dissolving the natural waxy coatings found on soft-bodied insects, including aphids, immature leafhoppers, mealy bugs, scales, spider mites, thrips, immature white flies, and eggs and pupae of other insects.

Gather the following supplies to make homemade insecticidal soap:

  • Spray Bottle: Use any clean spray bottle or garden sprayer.
  • Castile Soap: The active ingredient in insecticidal soap comes from the fatty acids in vegetable oils, so it’s important to use the real thing. Dr. Bronner's is one common brand.
  • Water: Tap water is perfectly fine for making insecticidal soap.

Mix together 1 tablespoon of soap to 2 cups of water and pour into the spray bottle.

The best time to spray insecticidal soap is early morning or evening when temperatures are cool, so the plant will stay wet longer. Apply thoroughly, and be sure to check the undersides of leaves. Insect infestations often require a second treatment with insecticidal soap in about a week. Wash vegetables and fruits before eating.

Happy gardening!


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