Insecticidal 'Soap'

ottawapepperJune 15, 2009


For those who mix up their own insecticidal soap versus buying the premixed stuff, I learned something recently that I thought IÂd pass along in case others like me, never really questioned Dishwashing Soap / Detergent / Liquid on store shelves.

-Liquids labelled dishwashing "soap" are "soap" based;

-Liquids labelled dishwashing "detergent" are, like the label says, detergents (not soap);

-Liquids labelled dishwashing "liquid" could be either soap or detergent or a combination. Check the ingredients well before using.

To make up an effective batch of insecticidal soap you need to use dishwashing soap.

Hopefully IÂm not the only one who didnÂt put 2 and 2 together all these years LOL.



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Do you have any links / recipes for making your own? Something's been doing a real number on all my pepper plants (but, not really bothering the tomatoes). I had insecticidal soap on my shopping list for tonight. :-)

    Bookmark   June 15, 2009 at 4:29PM
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Dissolve 5 ml (1 tsp) of liquid dish soap in 1 litre (4 cups) of water. Shake and spray on plants.

Note: Insecticidal soap is not a preventative measure. It acts on contact, which means that it must touch the insect pest in order to be effective.

    Bookmark   June 15, 2009 at 4:47PM
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chillilover(Zone 6b)

I bought ivory dishwashing liquid. Haven't used it yet. I heard dawn works but I can't find non antibacterial. What is the ingredient needed in the soap the kills the bugs?

    Bookmark   June 15, 2009 at 5:58PM
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Sounds simple enough (aside from having to re-apply constantly)! :-) Thanks!

    Bookmark   June 15, 2009 at 5:59PM
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bob_in_pc(z8 FL)

The key ingredient you're looking for when making up your own organic insecticidal soap is "potassium salt of fatty acids". Detergents, developed by the Germans, are a host of many different surfactant chemicals. Some are linear alkyl sulfonates, some are alcohols, etc.

Soap is the product of the saponification of fatty acids with alkali.

Though soaps make better insecticides,detergents make far better cleaning agents, mainly because of their ability to work well in hard water and not produce "scum" which happens when calcium/magnesium combine with the fatty acids.

    Bookmark   June 15, 2009 at 6:48PM
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So this doesnt hurt the plants in anyway, and how often can you spray them like once a week or once a day?

    Bookmark   June 15, 2009 at 8:25PM
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Good to know. Thanks. =)

    Bookmark   June 15, 2009 at 10:45PM
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chillilover(Zone 6b)

What soap can I buy that has this ingredient? They don't list them on the bottle and most dish soaps now are antibacterial which will kill beneficial bacteria.

    Bookmark   June 16, 2009 at 12:25AM
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bob_in_pc(z8 FL)

Murphy's Oil soap is one brand....

    Bookmark   June 16, 2009 at 8:19AM
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Hi again,

From what IÂve been told, bob in pcÂs comment regarding fatty acids in soap is the reason it works on some pests. IÂm "guessing" they stick to the pests and inhibit their respiration. Mind you, I still remember being made to wash my mouth out after being caught using foul language as a child. Biting into a bar of soap is not what you would call a gourmet experience LOL. Maybe the bugs donÂt like the taste either?

ndgrower, in the past I have used it daily for 7 or so days with no negative effects. However, spraying often could cause a build up of scum on leafs so if IÂm expecting dry weather I spray the plants down with clean fresh water half an hour or so after I apply the soap spray.

chililover, as bob in pc said, MurphyÂs Oil is one option. I'm not sure if our American friends can get it south of the 49th but up north here, Sunlight dishwashing soap is another option. If you canÂt find either locally you may want to try a health food / organic type store. They should carry natural soap products for cleaning.


    Bookmark   June 16, 2009 at 9:15AM
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chillilover(Zone 6b)

For the Murphys is it 1 tsp or 2 per litre?

    Bookmark   June 16, 2009 at 1:34PM
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I usually follow the following rules:

1) no intervention is best.
2) if I have to intervene, do so the least organic amount necessary working from minimal to stronger.
3) resort to full chemical warfare only when youÂre going to loose the plants anyway. YouÂll still probably loose the plants but you get some satisfaction out of unleashing the wrath of Dupont or Dow on the little buggers LMAO.

Seriously, IÂd start with one tsp per quart / liter and work my way up to two tsp if needed. I do recall someone once telling me to add a bit (?) of vegetable oil to it as well to help it stick. I never have but give it a shot if you like.

Hope this helps,


    Bookmark   June 16, 2009 at 3:59PM
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jessicavanderhoff(7 Md)

Just read a post by digdirt saying one tablespoon per gallon, whatever that works out to be in liters.

    Bookmark   June 18, 2009 at 4:09PM
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IÂve read similar recipes but always refer back to my rule #2.

FWIW 3 tsp = 1T and quarts and liters are pretty much the same. I did work up to 1.5T last year to fight a Thrips infestation.


    Bookmark   June 18, 2009 at 8:11PM
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Try Dr. Bronners soap. I saw it mentioned on "gardenweb" forum. Works for me.

Here is a link that might be useful: Dr. Bronner's magic Soaps

    Bookmark   June 18, 2009 at 10:38PM
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naturalstuff(Z6 / CT)

I hae holes in my leaves from some bugs...I'll try this homemade ingrediants...thanks.

    Bookmark   June 20, 2009 at 12:28PM
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I recently used insecticidal soap on my hot pepper plants. They were infested with stink bug nymphs who were reaking havoc on the foliage! I mixed 1 1/2 Tbs of dish soap, 2 cups water, 1 cup veg oil & 3 blended up & strained habeneros. Definetly killed the invaders. I could almost see them fold their arms and keel over, lol.
Be sure to spray directly at them, mist the undersides of the leaves as well as the top. Be sure to wash it away within an hour. I did it in late afternoon and unintentionally burned some leaves by not washing it away. Maybe I used detergent instead of soap like bill said. I was too worried about assasinating the critters who damaged my plants to pay attention to the label. I won't be making that mistake again. Point is, the stuff works. Keep the Sevin out of your garden.
I also used it to eliminate the hornworms killing my grape tomato plants!

    Bookmark   August 21, 2010 at 12:48AM
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johnweh(10 Boca Raton FL)

What about liquid hand soap?

    Bookmark   August 22, 2010 at 9:23AM
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I guess it's worth a shot Johnweh. I'd say play it safe and go buy some liquid dish soap.

    Bookmark   August 22, 2010 at 11:05AM
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I must agree with: "no intervention is best."

i have had bad luck in the past, trying to use the soap solution (bought and home-made) to get rid of those annoying pests.. flower drop, weakening of plants, etc..

maybe i got lucky this year, I separated the three plants that got infested. After 1+ weeks of daily inspection and removal of catepillars and aphids, they are bug free, and stronger than ever. it definitely takes some time to get up close and personal with your plants, but a flash light helps, and I think its worth it.

    Bookmark   August 23, 2010 at 8:06PM
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To each his own I guess. The insects were doing the damage and weakening my plants, not the soap. If you apply it right, and wash it away in a timely fashion, u shouldn't have a problem. I got a little lazy with the last plant to be washed and left a little soap on the top leaves. Some burning but nothing major. By far the insects caused much, much more damage than the soap. Maybe no intervention is best, but if you have a case like mine where you are going to lose some plants to pest infestation, why not take a shot?

    Bookmark   August 23, 2010 at 9:52PM
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My wife actually makes soap the old fashioned way with lye and oil in a big pot on the stove. Will this stuff work as insecticidal soap?

    Bookmark   October 22, 2011 at 11:20AM
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Hello everyone,
The only oil that I found that worked for me after trying all kinds was minerial oil. A few drops to gallon of water and a few drops of dishsoap. If you have plants inside and see spider webs. Act fast. Remove plants from growing station. Clean and clean and spray Lysol all over and repeat for two days. Mean while wash all plants down and spray wetable garden sulfur all over them. Shower the plants a few times and repeat every few days with garden sulter spray. This will help untill you can get your plants hardened off for the new season. The lysol will kill small bugs that are hiding. You can even fan the lysol spray in the air in the growing area while your plants are not there. Its great to wash your plants but you need to remember where they are growing also.

    Bookmark   October 23, 2011 at 11:20AM
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I'm not sure. My only familiarity with lye soap is based on Granny making it on the Beverly Hillbillies ;-))

If it's anything like the stuff Granny made, it might dissolve the plant as well as the pests!

Seriously, if you want to try it, I'd do a test on a plant you can live without in case it suffers adverse effects.


    Bookmark   October 23, 2011 at 12:27PM
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I recently posted an article on this topic at PEPPERMEISTER!. I purchased my organic insecticidal soap at Cross Country Nurseries (, phenomenal selection of high quality chile plants). It worked really well, but it seems silly to pay so much for something that's so easy to make yourself. I paid $19 for a bottle that lasted 3 weeks. So, now I'm using an all natural dish soap mixed with water, which cost about $6 for a bottle and will last me the entire season.

Here is a link that might be useful: read article on insecticidal soap at PEPPERMEISTER!

    Bookmark   October 23, 2011 at 6:12PM
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I have been using that soap every day for the last 15 years. I even wash my hair with it. So far, I am suffering no ill effects. If I find critters on my plants, I may just give it a is actually more natural than any dish soaps out there. There actually is no LYE in it once it is done. It goes through a chemical reaction where the lye and oils react into a completely different compound called "SOAP". If I do indeed use it, I will post the results on this forum.

    Bookmark   October 23, 2011 at 11:13PM
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Thanks for the info regarding lye. Home soap making is something that I've not experienced, yet.

My comments about Granny on the Beverly Hillbillies wasn't intended as a slight, I just have the image of her dissolving a boat paddle she was using to stir her soap.

If you have it and get pests give it a shot. If it's effective it'll be a 100% natural homemade defense.


    Bookmark   October 26, 2011 at 12:52PM
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