Potassium Soap Against Garden Pests

Last Updated on July 28, 2020 by Daniel Cooper

The potassium soap is able to control several of the common pests in the garden, without contaminating or cause problems for people and animals. Not in vain is accepted in organic farming for its zero toxicity. Then I explain its virtues and how to use them.

On many occasions, I have referred to this biocide as a remedy to some of the most common pests. I prefer to use ecological means in the garden, out of respect for the environment, yes; but also for more selfish reasons.

Potassium Soap Against Garden Pests

Potassium soap is an insecticide, and acaricide that effectively fights aphids, cochineal, whitefly, thrips, and red spider, among others; No toxicity for humans and other animals. Great, is not it …? Exactly, this is my great virtue for me. You can apply it without fear of causing damage to your body or your family, and your pets will also be safe.

Uses of Potassium Soap

This pesticide is accepted in organic agriculture; It can be applied in these crops without losing the certification. It does not enter the plant (it is not systemic), and it degrades quickly, so it does not require a safety term. Picking the fruits almost immediately would not be a problem.

In gardening, it is used without restrictions, unlike other phytosanitary products with more aggressive effects. This supposes that it is very used for the early control of the aphid, the cochineal, the white fly, the thrips and other insects of the soft cuticle.

Potassium Soap Against Garden Pests

In addition, it has a very interesting cleansing effect on the leaves: it washes the residues of molasses generated by the insects, avoiding the appearance of bold. It is also useful to combat this fungus at the beginning of the infection. The mites are not immune to its effect, being very competitive against the red spider.

The potassium soap can also be used along with neem oil or other plant protection. It is appropriate as “mojante,” improving the application on the plants (always check the manufacturer’s instructions).


Potassium soap is the result of the reaction of lipids (fats) with potassium hydroxide; To give it a liquid form, water is added. The process is similar to the manufacture of sodium soaps used as a detergent, but these are more aggressive (not appropriate in gardening).

If you are ever forced to use dishwashing soap or other similar as an insecticide, you should then rinse the product well with water. But this will not be necessary since potassium soap is easy to find. You can buy it at any garden center (also through this link to Amazon).

Potash soap will not harm the tissues of vegetables. In addition, when degraded, it will end up serving as fertilizer.

Potassium Soap Against Garden Pests


As you see, almost everything is advantageous with potassium soap: it is biodegradable and harmless. To top it all off, it is a source of potassium for the plants.

This ecological pesticide acts by contact; softening the protective cuticle of the parasites, which also use to breathe. It causes the suffocation of these, without harming other beneficial insects such as bees or their own natural predators, useful also to control the plague.

Because of its mechanism of action, you must be meticulous and apply the product well throughout the surface of the plant, trying to reach the largest number of individuals. Pay special attention to the growing parts, where the tissues are more tender, and do not forget the underside of the leaves; That’s where you’ll find more.

If you do not have a backpack for treatment, this 16l can be useful. Although for a punctual use it will suffice with a smaller sprayer. The best time to perform the treatment will be at sunrise or sunset, in the absence of wind and rain that was the application.

The dose may vary depending on the concentration of the product (see instructions on the package). But usually between 1 and 2% dilution in water, to ensure effectiveness. This would be 10 to 20ml of potassium soap for each liter of broth (for the 16l of the backpack, 320ml as much).

Several treatments to control the pest will be convenient. The idea is to repeat them between 3 and 4 times, leaving a week of rest between them.  The potassium soap, perhaps, is not the most effective pesticides, but less harmful to you and the environment.

This argument is for me more than enough, that’s why I recommend it to you. Before resorting to more aggressive products, is not it better to try something less harmful first? Also, well used and on time, who says it is not efficient. I think it’s always better not to start killing flies with cannon fire, and what do you think?


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