Castile Soap Spray for Garden Pests (Video)

As flattered as I am that pests find my garden delicious – after all, this is precisely my purpose in planting it – I still don’t want them there. Call me selfish, but I really want to eat my veggies myself, or feed them to my family and friends.  

Happily, the same Dr. Bronner’s Castile Soap that is designed for body washing is also, oddly enough, an eliminator of garden pests. Did you know this? 

I don’t fully understand why this is so, and a quick online search produced more possibilities than answers. However, it works! Best of all, there is nothing harmful to humans by spraying plants with a soap that is biodegradable, has no petrochemicals or synthetics, and is made from pure organic vegetable oils.  

As you’ll see in the video, you’ll need: 

  • A spray bottle  
  • 1 Tbsp. (15mL)  Dr. Bronner’s Castile Soap 
  • 1 quart (1 L) water  

I recommend a food-ish scent just in case the plants absorb some of the essential oils. Peppermint, Citrus, and Unscented are all great options. If your water is particularly hard, consider using distilled or filtered so that mineral deposits don’t build up on leaves. 

Combine the soap and water in a spray bottle. Spray plants thoroughly. Be sure to spray stems, and under the leaves where bugs hide. Spray early in the morning or evening so that the heat of the day does not evaporate the spray immediately and is effective longer. You may need to spray plants daily for a while to thwart an intense infestation. 

Although my research indicated that a soap spray will not harm beneficial insects like bees and ladybugs, you can be sure not to bother any by giving the plant a quick shake before spraying.  

Rinse your produce after harvesting. You can even add a drop or two more Castile soap, which makes a great produce wash. Happy plantings! 

24 thoughts on “Castile Soap Spray for Garden Pests (Video)

  1. can you use the castile soap and water on raspberry plants for flies

    • Hi Beverly- Soap has to be wet when it comes into contact with insects to be effective, which can make tackling flies tricky. Spray twice a day, on both sides of the leave, in the cool of the day until the infestation clears. Because flies are drawn to a source, take care to pick fruit as it ripens and remove overripe fruit.

  2. Thank you for this information.
    I hope it will ward off Beatles they are killing my roses 🌹

  3. I have a small caterpillar on my Currant bush that is eating all the leaves. Would Castile Soap eliminate these little buggers?

    • Hi Craig- I really don’t know. They don’t have exoskeletons, so I’m not sure the soap would affect them, but likely it wouldn’t hurt the plants if you want to give it a try. For slugs and snails, I’ve heard a dish of beer eliminates them. Not sure if it would work on caterpillars. If you try it, let me know!

    • Hi Craig, I actually had to tackle multiple small caterpillars enjoying my basil plant this morning. The spray works to knock them off, but they need an extra squirt to die. Once I sprayed and they fell to the ground, I squirted them 1-2 times more and they were dead.

  4. Hello Lisa. Thank you so much for the great information!
    Do you think I can blend some of our peppermint leaves in the water prior to adding the castile soap?

    • Hi Mike- That sounds lovely! There would not be a reaction with the Castile soap. Are you thinking that the natural mint oils may serve as a repellent? Let me know how it works. This blend will not be shelf stable, so make up what you will use in a couple days, or keep the mixture in the fridge for a week or so (I know that sounds odd).

  5. Excellent video! A related question – what do you do for weed control? I know you’ve mentioned that full strength all purpose spray castile will burn plants (so perhaps would kill them?), but can you use Dr. Bronner’s castile or Sal Suds for making a weed spray? I live in the mountains and have hearty weeds that I’m trying to get rid of but I don’t want to ruin the soil or surrounding plants and trees (my husband wants to use salt water, but I’ve read that that is pretty harsh to soil and surrounding plants). I’ve scoured your blog and comments, but can’t find anything on weeds… would love you thoughts!

    Thanks as always!

    • Hi Danielle- Thank you! I’m glad you enjoyed the post! For weeds, I would not use the Castile soap widely for the same reason as salt water. It could change your soil chemistry and render it difficult for growing anything. Because I am in such a dry climate where we get no rain from April to December, weeds aren’t as tenacious as elsewhere. I just clear them out by hand, pulling their roots. I realize this isn’t a solution for large areas. Let’s see what other readers have to say.

      Readers, can you share ideas on good weed control?

    • I have used white vinegar in the past—it’s great for the crabgrass on my concrete walkway–but it doesn’t discriminate, so be careful~~only spray vinegar on the weeds you want eliminated!

    • If it’s crabgrass I hope you find something and will share! If it’s others I’ve had wonderful luck with a good dose of just boiling water. It’s amazing how it’s gotten rid of those little buggers that grow along the walkway and driveway cracks. Might need to repeat it after a few weeks but no harm to the earth! 😉

    • You can also get a stronger vinegar at the feed store (20%) or garden supply. Adding a tsp of dish soap (or Dr Bronner’s) will make the vinegar adhere to the leaves of the weed. (Some gardeners add Epsom salts (magnesium sulfate) or table salt but horticultural experts say that both of these salts harm the soil.) It’s important to apply the solution early on a SUNNY day. You may have to apply it a second time to resistant weeds and you may have some weeds grow back but it has always worked great for me.

  6. Lisa,
    You were fabulous! I love the garden grounds so alive and fruitful .

    Aloha and stay well
    Katy

    • Hi Katy- Great to hear from you! Thanks for your kind words! For full disclosure, this is my sister-in-law’s garden because mine wasn’t doing much at the time we were filming, but I’ll be posting some pics of my own garden on Facebook pretty soon. It’s coming alive!

    • That’s great, Sheila! I’m glad this reached you at just the right time.

  7. WOW! ! ! I did not know this! But, I will try your suggestions. I an 74 years old and live in Phoenix AZ. I usually take the summer off from planting because not everything will grow in the summer here. Right now I still have tomatoes and Pepper plants, but I am sure they won’t last much longer! I will begin planting at the end of September, and will employ your suggestions then! Thank you sooooooo much!

    • Hi Peter- Yes! Like most animals other than humans, rodents can be deterred by mint.

  8. Good to know! I had a somewhat similar experience a few days ago. We had a plague of newly pupated tent worm caterpillars all over our deck. Last summer, they nearly decimated our mature trees. I grabbed a spray bottle the castile soap/water All Purpose Spray recipe and … sprayed them. It worked like magic. I happened to have just the plain castile soap in it. Simply amazing and so pleased to use something nontoxic and nonstaining.

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