Dr. Bronner's

Castile Soap Spray for Garden Pests

Castile Soap Spray for Garden

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.  

For the Castile soap spray for garden, 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! 

Further reading

Download Now!

Castile Soap Cheat Sheet

Dilute! Dilute! OK! But how much? Print this guide!


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Deanna Troi Bradshaw says:

Trying to kill grasshoppers! My poor garden is overrun! Wanted to try this as I need a pet safe option. Anyone know if it will work on grasshoppers??? Any suggestions? Please help.

Lisa Bronner says:

Hi Deanna- Oh no! As impressive looking as I think grasshoppers are (or at least the super big ones in my yard) I know they can be destructive in a garden. The Castile Soap Garden Spray doesn’t have any residual effect. Maybe someone here will respond with some ideas. Also ask at your local organic nursery.

August says:

Nice! I will try it. Hopefully those nuisance spider mites will leave my plants alone. Thank you!

Margaret says:

1. Will this solution (using peppermint as I’m allergic to citrus) slow down scale on my Japanese magnolia?
2. Will it repel biting midges (no seeums: Northern Ca) om a patio covered with trumpet vines & small recirculating fountain if I spray vines?

Lisa Bronner says:

Hi Margaret- Any of our scents will work in this solution, including Citrus. I haven’t tried the garden spray on scale, but I do think it would be effective on pests on your Japanese magnolia. Spray twice a day until the infestation clears. You can increase the amount and use a gallon-sized garden sprayer if your tree is large. The spray is only effective when wet, and won’t deter insects on your patio.

Susan says:

I have loved your soap for 50 yrs. It doesn’t leave a film or scum and leaves you squeaky clean! The peppermint works great on plants and repells mice. Wonderful product ❤️

William Forbes says:

How do you use the Peppermint soap to repel mice?

m says:

Hello, I found your tip on using Dr. Bronner’s Soap a year or two ago and it’s the best tip ever! I grow tomatoes and it does an amazing job at keeping away the bugs. I also realized that it deters birds from getting to my tomatoes before I do. I now use Dr. Bronner’s for all my garden vegetables and some of my flowers.

Lisa Bronner says:

Excellent! Thanks for sharing that our soaps are help in your garden!

Edwina says:

What is the dilution rate for tomatoes if I am using a two gallon sprayer?

Lisa Bronner says:

Hi Edwina- The ratio is 1 Tbsp. per quart or 1/2 cup in 2 gallons of water. Good luck with those tomatoes!

Kathryn says:

This is formation is great. I am using this all around the baseboards of my house.

Jimmy says:

the soap spray works because it dissolves the oils that make up the “shell” of the bug essentially and it kills them slowly that way(source: agriculture professor father )

Steven Zyla says:

Trying to kill Spider Mites on an indoor Cereal Milk. Rinsed the plant in the shower a sprayed it down. We shall see. Luckily the last two quarts of soap I bought were Peppermint. Fingers crossed! Thanks to your very professional staff. Steve Z.

Kathy says:

Hello I have a house plant that have kept out side for the summer and it has grown so big and beautiful. So I got a big enough tub to soak it. So I was wondering should I take it out of the pot to soak it or is better to soak it in the pot? And do I put the whole plant leaves and in the water? I wish I could download a picture of it but I don’t know how. The tub is 45 gallon.

Lisa Bronner says:

Hi Kathy – I am a “trial and error” gardener, but my thumb is somewhat green. As long as there are holes in the bottom of the pot, it will absorb water through them. Taking the plant out of the pot sounds like it could result in a significant mess in your tub. I would set the pot in the tub with a few inches of water and let the plant get a good drink.

Master Gardeners – Weigh in here on this!

About Lisa Bronner

My grandfather was Dr. Bronner, my family makes soap, and I share ways to use it plus tips on greener living.

Learn about my book, Soap & Soul!

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Print Now!

Castile Soap Cheat Sheet

Dilute! Dilute! OK! But how much? Print this guide!