How to make potassium soap - natural insecticide step by step

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Using products with artificial chemicals to take care of plants, both as fertilizers and products to prevent and treat pests, is dangerous for both plants and our health, depending on the specific product. For this reason, more and more people are choosing to use natural products to care for plants, to help them grow and to prevent and treat their conditions.

It is the case of potassium soap, potassium soap, or potash, which is an ideal natural product for plant care. If you still do not know it in Green Ecologist we explain what it is and what it is for exactly, how to make potassium soap and the dosage to use it correctly, enter more details. Learn how to do it and use it and you will see that your plants will thank you.

What is potassium soap and what is it for?

The potash or potassium soap It is a natural and ecological product that is highly effective in eliminating pests in plants, as well as helping to prevent them. This product is obtained thanks to the reaction of the saponification process that occurs when potassium hydroxide reacts with oil and water.

Basic composition of potassium soap

  • Water
  • Vegetable oil
  • Potassium hydroxide (KOH)

What is potassium soap for?

As we have already mentioned, potassium soap is used to control pests in plants and improve their health. It is especially effective against aphids, mealybugs and whiteflies, but it also treats other types of pests on plants and even fungi.

If you are looking to learn more about how to get rid of pests in orchards and gardens naturally, we recommend this other article by Green Ecologist on How to combat pests in organic farming.

How to make ecological potassium soap step by step

If you want to learn how to make natural insecticide with potassium soap or, what is the same, how to make organic potassium soap, don't miss this simple step by step:


  • Rubber gloves
  • Safety glasses
  • Kitchen scale
  • Blender
  • Plastic, glass, or stainless steel containers for storing soap

Protections are necessary because while the reaction between potash and water occurs, it can damage the skin and sensitive parts such as the eyes if it splashes, so prevention is better. Then once finished it is no longer so aggressive, neither for us nor for the plants but for a variety of pests of these.


  • 120 g of vegetable oil (olive, sunflower, corn or canola oil)
  • 20 g of potassium hydroxide (KOH)
  • 20g water

How to make potassium soap step by step

  1. Put on the protections (glasses and gloves).
  2. Mix the potash with the water and stir, you will see that the temperature increases while the reaction is taking place.
  3. In another bowl or container, pour the vegetable oil of your choice and heat it in a bain-marie in a pot. Let it heat up for a few minutes and then remove it from the heat.
  4. When the two are at room temperature, mix them together in one of the containers.
  5. You will see that it is acquiring a dark color. When it is more uniform, beat it with a mixer for 2 to 3 minutes.
  6. Let the whipped mixture rest for about 10 minutes and beat again for another 3 minutes, repeat as many times as you need until you get the texture you prefer. However, keep in mind that to use it later on your plants, you will have to mix it with water to dilute it.
  7. You can store it in the container you used to make the last mix if it has a lid, or store it in a plastic or glass bottle.

How to use potassium soap: the dose

Now, you just need to know how to use potassium soap on plants correctly. To be as effective as possible it will be necessary to ensure that cover the entire affected plant with potassium soap and insist on the areas that are most affected by the pest to be eliminated. As soon as the insects or parasites that affect the plant come into contact with the organic potassium soap they will die.

The potassium soap dose It is highly variable and depends on many factors, from the type of pest to be eliminated to the affected plant species to be treated. The most common dose of potash for plants is 1 or 2% of potassium soap in water.

The best way to use it once the dose has been prepared in the water is by spraying. Remember that as it is about moistening the entire plant, it is best to apply potassium soap on the plants when the sun does not hit them, to prevent them from burning.

For best results it is recommended apply potassium soap for 15 days over 3-4 months.

Where to buy potassium or potash soap

You may want to try the commercial product before you start making potassium soap at home. If you are looking where to buy potassium soap, we recommend that you go stores specializing in gardening, horticulture and agriculture or, to stores such as large supermarkets where they may have a gardening section. In addition, you can find it both in physical stores and in online stores. The price of potassium soap is around € 10 for an average 1L bottle.

If you use the commercial product instead of the one prepared at home, remember to follow the instructions on the product packaging and those that the specialist of the store where you purchased it has commented to you.

We recommend you also know this other article by Green Ecologist on How to make natural insecticides for plants.

If you want to read more articles similar to How to make potassium soap, we recommend that you enter our Garden Care category.

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