Potash soap characteristics and uses

This article was endorsed by Julián Masats - Technical agricultural engineer specialized in horticulture and gardening.

Potassium insecticide soap for pests

What is potash soap?

Potash soap is a product specially prepared to fight plant pests. It is a preparation based on vegetable oil and ash, although it can also be made with vegetable oil and caustic potash.

Properties of potash soap

Potash soap
Potash soap ecologic insecticide

Potash soap made with ash is less aggressive than soap made with caustic potash, so it is considered more ecological.

Potash soap is considered a good insecticide and fungicide, very useful to eliminate pests in plants such as aphids, woodlice, red spiders, as well as fungi such as mildew, powdery mildew, Botrytis, etc.

Applied on the plants, it covers the breathing holes of the insects, which it eliminates by suffocating them.

Uses of potash soap

In gardening and domestic horticulture it is used as an insecticide and fungicide.

Is potash soap safe?

It is considered a very safe remedy. It is biodegradable by the action of water and sun.

How is potash soap made? Potash soap recipe (with ash)

The formula of potash soap is as follows:

Ingredients of potash soap made with ash

Realization of potash soap made without caustic potash

burning wood
In this formula, ash is obtained by means of burning wood
  • Get ash from the wood. To do this, light a fire and let it completely consume until it turns into ash.
  • In a metal pot that is not aluminum, mix the ash from the wood with the liter of water. Let it rest for a couple of days.
  • Check the concentration of potassium carbonate in the mixture. To do this, introduce the potato into the mixture and check that it sinks halfway. If it does not float, add more ash to the mixture and wait another 48 hours to repeat the test.
  • Once verified that the potassium carbonate is the right one, go adding the oil to the mixture and stirring it until it acquires a pasty texture.
  • Place the mixture in an oven at high temperature and cook well until it acquires the texture of the soap. You can also boil in the microwave, making sure it does not spill.
  • Once the consistency of the soap has been reached, the pH should be measured. For this, we will use a pH measuring strip that can be purchased in drugstores. The proper pH of the potash soap should be between 8 and 9. If it is more alkaline, we will add a few drops of lemon until reaching the appropriate levels.

Conservation and use of potash soap made with wood ash

Keep the soap in a container until it is used as a fungicide or insecticide. When necessary, the soap is dissolved in a little water and introduced into a bottle with spray to fumigate the affected plants

Homemade potash soap for plants (formula with caustic potash)

Olive oil
Olive oil is a common ingredient to prepare potash soap

Ingredients of potash soap made with caustic potash

  • 1 liter of olive oil
  • 1 liter of water
  • 20 gr of caustic potash

Very important note !!! : Caustic potash is very dangerous because it can cause large skin burns. Protect eyes with protective goggles and use gloves. In case the skin splashes, apply vinegar to neutralize its effects. Do not use casseroles or aluminum spoons.

Realization of potash soap made with caustic potash

  • In a metal pot that is not aluminum, heat the water to about 40 º C
  • Add the caustic potash and stir well until the mixture is well dissolved.
  • Add the oil and keep stirring for more than an hour in a clockwise direction with a wooden stick
  • Let stand a couple of weeks to set well.

Conservation and use of potash soap made with caustic potash

Keep the soap in a container until it is used as a fungicide or insecticide. When necessary, the soap is dissolved in a little water and introduced into a bottle with spray to fumigate the affected plants.

punto rojo More information on ecological treatment of plant pests

Editorial
Written by Editorial Botanical-online team in charge of content writing

4 June, 2019

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Botanical-online is an informative page that describes, among other topics, the traditional uses of plants from a therapeutic point of view. Their descriptions do not replace professional advice. Botanical-online is not responsible for self-medication and recommends consulting with the physician.
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