Potassium Soap: What is it? What ingredients does it have? How do we prepare it?

Potassium soap (also known as potash or potassium soap) is an excellent organic remedy against pests, since its soapy action attacks the cell membranes of the external tissues of insects , affecting their external permeability and influencing their life cycle. .

It is also a great cleaning agent , which we can use, when diluted in water, to clean plants .

It is non-toxic, so it does not contaminate or cause problems for people and animals.

What is potassium soap?

Potassium soap is made up of three main elements : water, lipids and potassium hydroxide

When lipids come into contact with potassium hydroxide, a chemical reaction takes place , obtaining a water-soluble glycerin . This mixture has an alkaline pH and does not affect plant tissues.

In addition, it degrades quickly , so it does not require security periods to harvest the fruits.

Castalia Potassium Soap, K2O Potassium Solution, 5 L

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Last update 2021-06-10 / Affiliate Links / API Images for Affiliates

What is potassium soap made of?

Potassium soap consists of three main elements: water, fat, and potassium hydroxide.

When fats meet potassium hydroxide, a chemical reaction occurs, the result is mixed with water and liquid potassium soap is obtained. The resulting mixture does not affect plant tissues and its rapid degradation makes it a fertilizer for plants.

How can potassium soap be useful in your garden?

Potassium soap  is an excellent insecticide:  It is ecological, it does not attack beneficial insects, such as bees , and it can also be reused as compost , since when it decomposes it releases the carbonate of potash, which the roots can absorb.

It is also not harmful to pets or humans.

Potassium soap can also be used to prevent the appearance of fungus.

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Last update on 2021-06-09 / Affiliate Links / API Images for Affiliates

When should we use it?

We can use them at any time, although it is advisable to apply potassium soap at sunrise or sunset.

In addition, we must bear in mind that there is not too much sun because, when spraying the plant , it could burn the leaves. In the same way, we will have to be careful not to apply it on a rainy or windy day, since otherwise the rain will wash the application, or the wind will dry it, and the effort will not have been worth it.

How should potassium soap be applied?

Potassium soap works by direct contact. As soon as an insect lands on the substance, its minutes are numbered.

For this reason, it is essential to apply the product along the most tender areas of the plant , since they are usually the main access areas for most pests .

The correct dose will depend on several factors , mainly the type of plant and the severity of the pest.

In general terms, it is advisable to dilute a quantity of potassium soap in a proportion of 1 or 2% , or what is the same, about 10 or 20 ml of soap per liter of water.

The application system will be by spraying , making sure to cover both the beam and the underside. Preferably, do it very early in the morning, or at dusk, when the sun’s rays are not so intense, since the high temperatures cause the soap to burn the plants.

The treatment will work immediately, but sometimes the application must be repeated . For this, it is recommended to apply potassium soap every 15 days, within a period of 3 to 4 months.

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  • ✔️ DOES NOT CREATE RESISTANCES – Castalia Potassium Soap acts by contact destroying the protective layer of the insect and …
  • ✔️ SOURCE OF POTASSIUM – Its decomposition generates Potash Carbonate, which acts as fertilizer and corrects deficiencies …
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Last update on 2021-06-09 / Affiliate Links / API Images for Affiliates

What dose is the correct one when applying potassium soap?

Depending on the type of potassium soap, the dose to use will vary.

Potassium soap is generally used in a proportion of 1 or 2% dilution in water, that is, about 10 to 20 ml of soap per liter of water.

In any case, being a plant product, ecological and harmless, nothing will happen if at some point we exceed the dose.

This is something that we must take into account when using chemical pesticides that, in addition to negatively affecting the environment and ourselves, can also kill the plant in a fulminant way.

How to prepare potassium soap?


  • 1 liter of water.
  • 4kg of wood.
  • Lemon juice.
  • 1 liter of olive oil.
  • 1 potato


  • Metal pot.
  • Packaging containers.
  • Metal stirrer.
  • Instrument for measuring pH.

Procedure for making potassium soap

  1. Burn the wood and wait for it to be completely consumed.
  2. Collect the ash and place it in the metal pot, later adding a liter of water. Shake until you get a homogeneous mixture.
  3. Let it rest for 3 days.
  4. After that period , place the potato in the mixture. This will help us determine if the potassium carbonate concentration is valid . If the potato floats, it means that the concentration is acceptable. Otherwise, the process will have to be repeated, this time with a little more ash.
  5. If the concentration is good , add 1 liter of olive oil and shake until you get a homogeneous mixture. The texture should be thick and thick. This glycerin is already considered potassium soap.
  6. Now, we need to measure the pH of the mixture. For this, you can use a pH measuring strip . If the pH is between 8.0 or 9.0, it means that the result is alkaline, so you should add 5 drops of lemon to reduce the values.
  7. To apply, you just have to dilute in water , according to your specific needs.

What pests can we fight with it?

It works to eliminate soft-bodied insects and arthropods , such as mites, aphids , whiteflies , mealybugs , grooved mealybugs , thrips , among others.

It is also useful for eliminating caterpillars , leafminers and grasshoppers, but these insects , due to their size, can be more difficult to control with this method alone.

As for pollinating insects, such as ladybugs, bees, bumblebees and flying flies, they are not affected.

There are different ways that potassium soap works to kill insects:
  • Entering through the trachea of ​​the insect , which causes an alteration of its cell membranes .
  • Soap can dissolve attacks the cell membranes of external tissues , as well as the wax layer on the cuticle of insects , affecting their external permeability and influencing their life cycle.
  • It can also block the windpipe or any other form of breathing , leading to the suffocation of the insect.
  • Finally, it can interfere with growth hormones or affect the metabolism of insects.

Main advantages of potassium soap

 Effective insecticide and repellent:  Potassium soap can be used to prevent pests, how to combat them once they have manifested themselves.

Cleaning agent: Diluted in water, helps to clean the plants. It can be an excellent remedy to combat dust in our crops.

It integrates very well with other remedies , such as insecticides, fertilizers or fungicides , as long as they have a pH that is above 10 . This way we make sure that we don’t have any compatibility problems.

Potassium soap can be used at any stage of plant growth , it is even valid to apply at the beginning of the transition from the flowering stage.

Despite its cost, it is a very profitable solution , offering an excellent cost-benefit ratio.

Where to buy potassium soap?

We buy our boats directly from Amazon ( here ) and it gives us good results.

However, it can be purchased at any specialized store.

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  • Potassium soap, 100% BIO that acts by effective contact against all types of pests.
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Last update on 2021-06-11 / Affiliate Links / API Images for Affiliates

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  • It constitutes the best cupric contribution to maintain plant tissues at optimal levels of health.

Last update on 2021-06-11 / Affiliate Links / API Images for Affiliates

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