Spraying for Garden Pests

It’s that time of year again! Now that our gardens are in full swing, the bugs are relishing the menu. Insecticidal soap, made from Dr. Bronner’s Pure-Castile Soap works very well in ridding your plants of these pesky pests.


  • Spray bottle
  • Castile soap (any variety – but there is a chance you’ll taste the essential oils, so you may want to go with the Baby Unscented or Peppermint)
  • Cayenne pepper, cinnamon, or powdered garlic
  • Water

102 thoughts on “Spraying for Garden Pests

  1. Do any of your products work on fleas? Either on the dog itself, or sprayed in the house or outside? There are so few options other than actual poisons. Diatomaceous earth can help, but who wants it sprinkled all over their house!

    • Hi Mary – Our Pure Castile soaps work very well on getting rid of fleas on animals. The peppermint is usually my go-to because of the naturally deterring effect of peppermint, but any of them will work. Check out my post on washing dogs with castile, http://www.lisabronner.com/washing-the-dog-with-dr-bronners/. I don’t know that the soap will effectively eliminate fleas from carpets and other soft furnishings where they like to live around the house. Even with a carpet cleaner, it would be tough to reach all the nooks with enough heat and soap to kill any fleas and eggs. If you can wash dog beds and blankets in castile soap, that’s a great start. This post may help you with that, http://www.lisabronner.com/dust-mites-and-castile-soap/. Hope this helps!

    • Dr. Bronner’s Pure Castile soap is faster at killing fleas on an animal than any other product I’ve used! I started using it out of our foaming hand soap dispenser to kill the ones I combed off of our cats. The surface tension of the soap combined with the small bubbles seems to trap them pretty quickly and smother them. I’ve experimented with using as small an amount as possible and it’s still effective. II really hate killing living beings but I’ve done the Happy Dance over the demise of these fleas on more than one occasion. I have also bathed our long haired large dog using it and it works so quickly that the fleas don’t even have a chance to run! It does leave her coat dry and I’d think that, with repeated use, it may be drying to her skin. I followed up with a second wash with a conditioning shampoo and a vinegar spray rinse that left her soft.

    • Hi there – The soap stops insects by dissolving their exoskeletons. Larvae and caterpillars don’t have this, but I still think they might not like the soap. I can’t give you a definitive answer.

      Can any other readers weigh in here?

  2. I discovered aphids in my garden several days ago. I tried just blasting them with some water but that didn’t seem to help. After doing this for a couple of days and watching the population just increasing, I did some research and discovered the relationship between those aphids and ants. So I began sprinkling DE on my garden and again water blasting the ants for a couple of days. Again I found the aphid population continuing to increase and spreading to other plants. Thank goodness I found a recipe on YouTube that said to use a 1 gallon garden sprayer with 2 1/2 to 5 Tbsp of Dr. Bronner’s castile soap. I went with the lower soap amount and sprayed my plants. The next day, today, I found more than half of the aphid population gone. We got 2 inches of rain last night so I sprayed again today. I am thinking of adding the cayenne pepper or garlic to keep those leaf eaters off too. Thanks for all you do!

  3. We use Castile soap in a foaming dispenser for hand washing. Recently we’ve been invaded by Japanese beetles. I put about an inch of foam in the bottom of a jar and took it out to the garden and knocked them into it. They were dead before the sunk out of sight. I wondered if mixing into a spray and dispensing onto the plants would be effective? Also I wondered if I could spray this on wasp nests that are built at the peak of my house? And if it would damage my vinyl siding? Any help would be appreciated.

    • Hi Ron – Wow! Great testimonial! A spray of the soap and water would kill japanese beetles on contact, but the residue of it is not an effective deterrent. In other words, it only works when wet.

      Regarding the wasps, I have never tried going after wasps with the soap. Theoretically, it would probably stop hurt them, but again, it would only work when wet, and it would have to be a direct hit. A mist around them wouldn’t be effective. My concern is that in the process of trying to hit them, you might get them mad and riled up, and this method could seriously backfire.

      It wouldn’t damage your vinyl siding, though.

  4. Aphids are natures cleanup crew. An indicator that something is out of balance. Typically using liquid fertilizers like Miracle Grow will increase aphid populations. The plants are under some sort of stress usually an excess of nitrogen fertilizer. A critical part of controlling aphids it to also control ants. They will protect the aphids to keep those sugars coming. Aphids excrete sugars.

    3 TBS soap to G of water add 1 TBS of 70% alcohol.

    Better yet 2TBS Peppermint soap and 1TBS of vegetable oil.

    Recipes from my years as horticulture director for The Mirage Hotel

    • Great info! Thank you for sharing!

      Which recipe would you suggest if combining all three…Castile soap, a vegetable oil and alcohol?

      What alcohol is safe and cost effective?

  5. Will this recipe work on apple trees and apples with out leaving a taste or health effects, but still protect the apples from bugs that seem to bore into the apples this time of year.

    • Hi Bob – The soap solution would have to come into contact with the insects when it is wet. The residue does nothing. So, if you have an infestation where you can see the bugs, the soap will help. If the damage is being done when your back is turned, it won’t. I don’t know what types of pests affect apples, but the soap solution works for bugs with exoskeletons. I don’t know that it would work on any kind of worm or caterpillar. As far as health goes, it is completely healthy and I do not think it would affect the taste of the apples, but perhaps use one of the food-ish scents just in case, such as almond.

  6. The recipe portion of the page seems to have disappeared – using Chrome browser. This is true for the household cleaning spray page as well. Is it just for me, or is there something gone weird with the page? I can see the post title and date, then down thru the supplies you need, then it’s just blank until the Comments.

    • Hi Jac – There’s actually a video inserted there in which I shared the recipe and I didn’t have the recipe typed out, for some reason. Here it is:
      In a spray bottle combine 1 quart water and 1 Tablespoon soap. This is all I do, but if you want to be fancier you can throw in a couple extras:
      Optional add-ins are cayenne pepper, garlic powder or cinnamon which can all provide additional deterrence. You can also add 1 Tbsp. of vegetable oil so that the solution doesn’t evaporate immediately off the plant, but with the oil, the solution will go rancid more quickly.

    • Thanks, Lisa! Perfect timing for me here in California. Many buggy plants right now. I sure hope it rains soon. I’m glad I rediscovered Dr Bronnee’s. I am SO enjoying all your products!

  7. wondering about pest control, particularily spiders in the house, got your name from 1001 natural secrets to pest control by Dr. Myles Bader referring to your products such as peppermint oil pennyroyal, peppermint soap, a product called Jungle Rain, cocanut oil and white vinagar to stop cobwebs, he even suggests hedgeapple from the Osage orange tree placed in the affected rooms, even fresh chestnuts placed across any entry point to keep them out. Just wondering your experience with these products for pest control. Thanks Tom

  8. There’s a video on YouTube with the owner of Boogie Brew is using Dr Bonner’s Sal Sud soap as a pesticide. Which in your opinion is actually better to use. The Sal Sud or the Peppermint.
    Thanks in advance.

  9. Hi, I would like to spray the black ants which are all around the plant, I want to know if the mentioned concentration will affect the plant? I don’t want to kill my plant but the black ants have make the plant as a home.

  10. Time for true confessions, folks. It is February 9, 2017, and I have missed several months of comments for the simple reasons that things went a little crazy around here. I very much apologize. I am tackling them now for the sake of those faithful and new readers who might actually read them all. I am going to start with the most recent. Bear with me.

    • Thank you for your care Lisa! Ive had this page/recipe bookmarked for 2 years now. I just came back to make a batch to kill some aphids on my violas. i read through every comment and response to get the most info on making a knockout soap spray. I just saw your last entry not even a month ago and i wanted to say that i really appreciate you coming back and expressing that to those of us who need you and your valuable advice. Positive vibes to you and i hope things are running a bit smoother for you now. We all know how our lives can get crazy. Cheers and Thanks again.

    • Thank you and you’re welcome, Mabelle! As you can see, though, I don’t get to every page often, but I do try to make it around.

  11. Will a Castile soap spray kill or deter lady bugs? I added lady bugs purchased from the nursery to my garden, and I hate to deter them.
    Any input is appreciated.

    • Hi James – Yes, the Castile soap would kill the lady bugs. I wouldn’t use both pest remedies at the same time.

  12. hi! i love your soap and use it on everything. when looking for a𝐍𝐚𝐭𝐮𝐫𝐚𝐥 natural solution to killing aphids on my japanese eggplant plant, i saw that i could use the soap in a water solution and was so excited! i also sprayed the plant with water after an hour or so after the solution to rinse the soap off, but it VERY quickly wilted, and not just the leaves but the entire plant- stems and all! it’s been three hours and it seems to be getting worse. what can i do to save it? please help! 🙁

    • Hi Jessica – I am so sorry to hear this and that I missed this earlier. Sometimes too strong a concentration of soap solution can harm a plant that’s already fragile from insect damage. Also, if the spray is applied under a very strong sun it can end up burning the plant. Did the plant recover after a good watering?

    • Hi Stefanie – Yes, it would work against thrips.

  13. Hi, you may have already answered this question, but is this mixture good for herbs? I don’t have a green thumb and have no idea what bugs are eating up my herbs, but I do know I want a natural repellent to take those suckers down. Thanks!

    • Hi Lani – Yes, this would be great on herbs. Perhaps try one of the more foody scents, such as Citrus, just in case the essential oil sinks into the leaves. It would not be harmful at all, but you might taste it.

  14. Hi, strange as it sounds caterpillars do have exoskeletons. That’s why they have to shed their skins to grow. Caterpillar exoskeletons are very thin because they are largely unsclerotized (sclerotization is the hardening of an insect’s exoskeleton that makes most insects hard-shelled). This is because they are basically eating machines and must be able to expand considerably more than a hard exoskeleton would allow. You can google it.

    • Thanks for weighing in, Victoria! I don’t know enough about this.

  15. Will this mixture work to spray on humans to repel the sweat bees?

    • Hi Tracy – No, it doesn’t work particularly as a repellent. It only affects bugs that it contacts while it’s wet. After it dries, it doesn’t have an effect.

  16. Hello,
    I only have a quart spray bottle.
    What are the exact measurements of Dr. Bronners, Garlic Powder, Olive Oil, etc if only using a quart of water.
    Can I use this on outdoor citrus trees like lemon, lime, satsuma, grapefruits, etc?
    I also have Zuchinni, Spinach and other flowers like Blue Glory Vine, Hidden Ginger.
    Can this solution be used on all these?

    • Hi Jennifer – For a quart bottle, add 1 Tablespoon (15 mL) Castile soap. You can use 1/8 tsp. of garlic or cayenne pepper. I don’t use the olive oil because it goes rancid in the bottle and leaves my plants sticky, but perhaps another reader who does could share their measurements. You can use this on any plant or tree, but it only works if the wet solution comes into contact with the bugs. The residue does not affect them after it dries. It would be pretty difficult to spray a tree thoroughly enough, especially with a quart spray bottle, but if your tree is potted or otherwise small, or if the infestation is pretty isolated, you might be able to treat it this way. Another natural option for deterring crawling insects from getting into your tree is to sprinkle the base with diatomaceous earth.

  17. Thank you for this post – I’ve been spraying the soap spray (1 tablespoon peppermint Dr. Bronner’s in 1 quart of water) on my roses, and it’s really helped with a major bug infestation (without hurting the bees I also have buzzing around my yard!). As you said, the spray has to hit the bug to be effective (no residual effect), so I’ve been spraying every day to get the situation under control. Thanks again, from me & my roses! P.S. Also worked to get ants off of a dwarf citrus tree.

  18. Just to add, growing broccoli for the 1st time btw, I was told about how nasty boiling worms from the heads was by a customer at a local gh. So after planting I watched daily after 3/4 weeks I giggled to myself bc I had not one bite mark anywhere. Due to life getting a bit nutty for a couple weeks, I didn’t check but 2x a week max. Bam! eat to death in a few days as heads began to show.. Just purchasing Castile peppermint for the 1st time I thought ill try it. Mixed a water soap 2 tea 1 qt water and sprayed the plants all over because I could not see anything…. I thought…. Little worms colored identical green to the stalks started hitting the dirt.
    2 weeks later plus a few more applications… Lovely bite free broccoli… Still awaiting growth to remove head but im thinking if I have to boil maybe much less nastiness will arise from the head.

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