Castile Soap (as Insecticide)
Quick Facts
- Type
- DIY fatty acid insecticide
- Source
- True castile soap from plant oils saponified with potassium hydroxide
- OMRI Listed
- No
- Bee Safe
- Yes
- Pet Safe
- Yes
- Residual
- None — contact kill only while wet
- Best For
- Budget insecticidal soap. Emulsifier for neem DIY sprays.
What Is Castile Soap (as Insecticide)?
Potassium salts of fatty acids disrupt insect cell membranes and strip protective wax. Same chemistry as commercial insecticidal soap.
Source: True castile soap from plant oils saponified with potassium hydroxide
What Pests Does Castile Soap (as Insecticide) Kill?
Castile Soap (as Insecticide) is effective against the following pests:
How to Apply Castile Soap (as Insecticide)
Best for: Budget insecticidal soap. Emulsifier for neem DIY sprays.
Avoid for: Sensitive plants (ferns, new seedlings). Hard water without correction.
Residual activity: None — contact kill only while wet
Safety Profile
| Category | Rating |
|---|---|
| Bee Safety | 🟢 Safe for bees |
| Pet Safety | 🟢 Safe for pets |
| Overall Rating | Safe — Safe for kids, pets, and bees when used as directed |
Why Isn't Castile Soap (as Insecticide) Working?
If Castile Soap (as Insecticide) isn't delivering results, check these common failure modes:
Wrong concentration burns plants
NEVER use dish soap
Hard water reduces effectiveness
Must be true castile (KOH-saponified)
DIY Castile Soap (as Insecticide) Recipe
2.5 tablespoons pure castile soap per gallon of soft water. Spray directly on insects. Rinse plants after 2 hours if concerned.
Best Castile Soap (as Insecticide) Products
Dr. Bronner's Pure Castile
Liquid soapUnscented is best for plants