killing aphids with soapy water

Killing Aphids with Soapy Water: Is It Safe & Effective?

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Is killing aphids with soapy water an effective and safe option for your garden? This article explores all you need to know.

The underside of a cucumber leaf infested with aphids

Are you looking to kill aphids in your garden using practical, simple ways?

Killing aphids with soapy water just might be the break you need to prevent them from sucking your plants dry.

If you’re tired of watching your plant foliage wilt and curl up like a scared hedgehog, keep reading. This article discusses important tidbits you should know if you’re considering killing aphids with soapy water.

How Does Killing Aphids with Soapy Water Works?

Soaps work by interrupting the cell membranes of aphids. As the protective exterior—wax— is damaged, cell content leaks out, and the insect becomes dehydrated and dies.

Killing aphids with soapy water also works through a smothering or suffocating process. The exoskeleton of the aphid becomes covered in soap that it’s smothered to death.

Although it’s not fully understood as to how soap works to kill aphids (and other soft-bodied insects), it has been used for over 200 years.

This gives rise to an important question. Is killing aphids with soapy water effective? Let’s jump into it.

Is Killing Aphids with Soapy Water Effective?

How do you define “effective”? For any product to be “effective” it has to succeed in carrying out the task for which it is used. Does soapy water kill aphids?


To supplement, killing aphids with soapy water has many other benefits for your garden.

1. Low Toxicity

In addition to the fact that soapy water kills aphids, the solution is of least concern with regards to toxicity. Unlike other interventions used to kill aphids, once applied, soapy water does not produce a residual impact.

If you spray a bunch of leaves directly with soapy water, and then another insect—perhaps a beneficial one—crawls onto the sprayed leaf, it’ll not be killed.

2.   Inexpensive to Acquire

Killing aphids with soapy water is a budget-friendly pest control option. If you’ve had to treat other pest problems, perhaps in your home or garden, you know how expensive things can get.

Using soap as an insecticide is easy to acquire and, in most cases, many homeowners already have a liquid soap that is safe to use.

3.   Ease of Use

Who doesn’t know how to spritz water from a spray bottle?

This is one of the easiest methods to kill aphids. Once your soapy water solution is put together, locate the perpetrators on your plants, aim and shoot to kill.

With all things considered, killing aphids with soapy water is a great option to look at. Since it’s effective, let’s explore whether it’s a safe option.

Is Killing Aphids with Soapy Water Safe?


Killing aphids with soapy water is safe.

But, as with every product or treatment you’ll use in your garden, it must be used for the intended purpose and according to label.

Since you’ll likely be making your own soapy water solution, there’s no label for you to follow. However, heeding a few guidelines will help to ensure killing aphids with soapy water is safe for your garden.

Do you have a tomato garden? Aphids love tomatoes, and probably more than you do. Check out this article to learn how to get rid of aphids on tomatoes in your garden.

If you have kids who support you in cultivating and maintaining the garden, soapy water is safe for use around them. This is also the case if you have pets. Your dog is free to roam wild in your garden after you’ve treated your plants

Killing aphids with soapy water is also safe as there’s no residual impact. This means that beneficial insects, unless directly targeted, will not be harmed.

To supplement, soapy water is relatively safe for plants. Why ‘relatively’? Some products are phytotoxic to plants. But, you can bypass this sort of sensitivity if you follow the suggestions.

Did you know that research shows that garlic extract repels aphids from your garden, and at the same time attracts predatory insects of aphids like lady beetles and lacewings? This article provides a DIY aphid spray that is suitable for garden use.

Tips for Killing Aphids with Soapy Water

These tips should be followed if you want to successfully kill aphids with soap and water.

  • Do not use more than 1-2% solution.
  • Choose your soap wisely. Better success can be had with liquid castile soap, not the typical laundry detergent. Castile soap is vegetable-based, and with organic options on the market. So, if you have an organic garden, give this a try. Check out this article for more organic ways to get rid of aphids.
  • Be mindful of when you apply your soapy water. Never add soapy water to your plants when the temperature is hot. It’s best to use your soapy water solution early mornings and late evenings when it’s cool.
  • Spray directly to affected leaves and plants. As mentioned before, soapy water kills aphids by smothering. You have to completely cover them with the solution to get success.
  • Always check to determine how your plants will react to a soapy water solution. Spray a small area of your plant (sometimes a leaf or two will suffice). If the plant begins to wilt or leaves transform to brown or yellow, that’s a sign of phototoxicity. If this happens, spray fresh, clean water onto plant leaves.
  • In some cases, you can dilute your soapy water solution with more water if you deem it’s too strong.

Do you find it challenging to protect your garden from aphids? Learn 7 different methods you can use to get rid of aphids in your garden today.

Remember, even drinking too much water can cause harm. The point is, even the safest pest control method, when misused, or used inappropriately can cause harm. Always follow instructions and when introducing new products and interventions to your plants, conduct a test first, the same way you’d do a patch test when introducing a new moisturizer to your skin.

Start killing aphids with soap and water today, and you’ll enjoy more plant yield, beautiful foliage, and fewer fruits becoming inedible as a result of a plant disease. If you’re interested in exploring other ways to kill aphids, chemical control is also an available option.

Can you get rid of aphids permanently? Click the link to learn more.

How to Get Rid of Aphids Permanently – The Bug Agenda
killing aphids with soapy water
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13 responses to “Killing Aphids with Soapy Water: Is It Safe & Effective?”

  1. Brook Avatar

    How much soap would you suggest I use in water? Thanks.

    1. The Bug Agenda Avatar
      The Bug Agenda

      2 to 3 tablespoons of liquid soap in 700 ml to 1 litre of water should suffice. Before applying to your plants, ensure to test a small area. If there’s any sign of phytotoxicity, dilute your solution with more water.

  2. Daina Avatar

    Thank you! I’ve actually been searching to learn more about soapy water and how it works to control aphids. How often should I use this in my garden? Does it only kill aphids?

    1. The Bug Agenda Avatar
      The Bug Agenda

      You can use this solution every 3 to 7 days. No, it doesn’t only kill aphids. You can use it for soft-bodied insects such as mealybugs.

      1. J. Jarrard Avatar
        J. Jarrard

        Kills spider mites as well!!!

        1. The Bug Agenda Avatar
          The Bug Agenda

          It does. Thanks for adding that bit of info.

  3. Shawn Avatar

    Are these the same things as plant lice? They look the same to me. The ones I have in my garden are black though. Can I use soapy water on them too?

    1. The Bug Agenda Avatar
      The Bug Agenda

      Yes. Aphids are also known as plant lice. The black aphids in your garden are called black bean aphids. And yes, you can use soapy water on these, too. Ensure to cover them thoroughly with your soapy water spray.

  4. […] the video below for a demonstration, and read the article to learn why soapy water is safe and effective. From the article, you’ll also learn a few guidelines that’ll keep your plants […]

  5. Julie Petersen Avatar
    Julie Petersen

    I used the soapy solution a couple days ago before reading the article. (Thanks for it by the way) When I was done spraying all the pepper leaves, I sprayed clean water up to the underside of the leaves to rinse them off. Did that help, or nullify the effect of the soap?

    1. The Bug Agenda Avatar
      The Bug Agenda

      I wouldn’t say ‘nullify’. It all depends on how long the soapy water sat on the leaves. But it doesn’t actually take much to breakdown the exterior of aphids, since they are soft-bodied. Perhaps wait a few minutes before washing the leaves off the next time.

  6. Marilyn Avatar

    I agree it only takes a few minutes to kill the aphids. Two tables spoons of Dawn in a quart of water or less. Always rinse well and repeat in a day or two if necessary and I avoided the flower blooms.

    1. The Bug Agenda Avatar
      The Bug Agenda

      Thank you for sharing your throughts. Appreciate it.

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