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Gardening Area => Plant Pests & Infections => Topic started by: TBM on February 20, 2016, 09:13:34 PM

Title: Insecticidal Soap: aka Potassium Salts of Fatty Acids
Post by: TBM on February 20, 2016, 09:13:34 PM

Can be found online as concentrate or in premixed spray bottles. Due to the low toxicity to humans, it is accepted as useful in organic gardening. In order to work, the affected plant must be fully soaked with a solution, as it loses its effectiveness after drying. Read manufacture labeling for proper application.


It's effectiveness isn't completely understood, but it is thought to work mostly by mechanical means, such as:

• Soaps entering insects trachea, disrupting cell membranes
• Soaps dissolving the insect's waxy outer layer, leading to dehydration
• Soaps blocking respiration, causing suffocation
• Possibly affecting hormones and metabolisms

Insecticidal soaps are most effective against soft-bodied insects, such as aphids, thrips, scale insects, etc.


Some plants are sensitive to insecticidal soaps. Younger/fresh transplants/unrooted cuttings will be more susceptible to damage. Damage to plants may present as:

• Yellow or brown spots
• Burned leaf tips
• Leaf scorch

Title: Re: Insecticidal Soap: aka Potassium Salts of Fatty Acids
Post by: TBM on March 09, 2016, 08:15:17 PM

From the label of an insecticidal soap spray bottle:


Do not use on:

• Euphorbias
• Gardenias
• Delicate ferns

Plants you should consider testing for sensitivity before use:

• Azaleas
• Begonias
• Camellias
• Fuschias
• Impatiens
• Jade plants
• Palms