Marseille soap to get rid of insects harmful to plants: an all-natural remedy

by Mark Bennett

April 30, 2024

Gardener spraying insecticide on plants and a bar of Marseille soap

Most insects are harmless, but there are some that can be damaging to our plants and vegetables. These pests include aphids, scaled insects, weevils, thrips, mealybugs and more. To repel these insects, you can make a DIY spray using Marseille soap (which is an all-natural remedy that will not harm the plants).

Why use Marseille soap to combat parasites?

a bar of Marseille soap


Using Marseille soap to protect plants is a remedy that has been used for years: it is an affordable alternative to commercial insecticides of all kinds, and is effective against a developing infestation.

What are the advantages of Marseille soap?

  • This soap is all-natural and biodegradable and does not contain chemical additives. In its original form, it is made with olive oil (or sometimes with other vegetable oils), water, salt and soda. This makes it completely biodegradable and therefore eco-friendly.
  • It works well as an insecticide. The fatty acids in the soap can dissolve the parsites' cuticles (ie. the surface layer that protects the body of insects). Breaking this "armor" degrades the insect's internal fluids and cells, leading to its death.


How to make a homemade insecticide with Marseille soap

A gardener spraying a pesticide onto plants

Tima Miroshnichenko/Pexels

To prepare a Marseille soap insecticide, you will need:

  • 15 grams of Marseille soap flakes
  • 1 liter of water
  • (optional) a few drops of Neem oil
  • A spray bottle (glass is always best, but plastic will do)
  • A saucepan
  • A funnel


  • Grate the Marseille soap into fine flakes (if you can't buy it in flake form).
  • Dissolve the flakes in warm water in a saucepan, mixing well until they are completely dissolved.
  • Leave everything to cool down.
  • Once cool, pour the solution into the spray bottle (using the funnel).

Using this DIY insecticide

  • Shake the spray bottle well before each use.
  • Spray the solution on the leaves and stems of the plants, in the morning or in the evening (and never during the hottest hours of the day, especially in summer).
  • Repeat this application every 3-4 days, or more often, if necessary.

Neem oil can be used to make your spray more effective: you just need to add 3-5 drops of Neem oil to the solution in the spray bottle.

Further advice and warnings

  • Store your spray in a dark and cool place.
  • Avoid using the spray on more delicate plants, such as exotic ferns or orchids.
  • If you do not notice significant improvements within about 7-10 days, you may need to try something else (consult an expert).

Have you ever used Marseille soap as an insecticide?