Neem Oil vs. Insecticidal Soap – Differences + Which to Use

Insecticidal soap and neem oil are popular organic insecticides used for treating different types of pests on plants, including aphids, whiteflies, spider mites, mealybugs, thrips, and scale insects.

While both of these organic insecticides are considered safe on plants and animals, they have different properties and abilities. In summary, here’s what to know about neem oil and insecticial soap.

Neem oil	Insecticidal Soap
It is extracted from neem tree seeds.	Made from potassium salts of fatty acids.
It covers the insect’s body, blocking its breathing openings, reduces feeding, and interferes with its hormonal system.	Removes the protective waxes that cover insects, disrupt the structure and permeability of cell membranes, and cause dehydration that kills the cell.
Leaves an oily residue on plants that can be difficult to wash off.	Leaves little to no residue on plants. This makes them safe on beneficial insects and pollinators after the spray dries.
Effective against a wide range of pests and fungal diseases.	Effective against soft-bodied insects and young ones.
Breaks down slowly and provides long-lasting control of pests.	Breaks down quickly and requires frequent applications.
More expensive compared to insecticidal soap.	It is less expensive compared to neem oil.

Neem Oil vs. Insecticidal soap 

If you have a pest problem on your cactus or other plants, neem oil and insecticidal soap are the safest pesticides you can use. However, to choose one, knowing their differences and how they work is important.

Neem oil

Neem oil is a vegetable oil extracted from the seeds of the neem tree (Azadirachta indica), native to India and other parts of Southeast Asia. It is deep yellow in color, has a bitter taste, and has a garlic or sulfur smell.

Over many years, neem oil has been used in traditional Indian medicine and as a natural pesticide. It contains a number of compounds, including azadirachtin, the most active ingredient responsible for its insecticidal properties. 

Neem oil is effective against a wide range of pests. It reduces insect feeding and interferes with insect hormone systems, making it harder for insects to grow and lay eggs. Explains National Pesticide information center.

Neem oil can be applied to plants as a spray and mixed with water. It is important to carefully read and follow the instructions on the label of your neem oil product to ensure safe and effective use.

Insecticidal soap

Insecticidal soap is an organic insecticide made from potassium salts of fatty acids. It breaks down the outer protective wax coating on insects upon contact, causing it to dehydrate and die. Explain North Carolina State University 

This soap does not harm humans or other wildlife, making it a safer alternative to synthetic pesticides. However, it is important to carefully read and follow the instructions on the product label for safe and effective use.

Insecticidal soap is available in ready-to-use sprays and concentrated formulas that can be diluted with water. It is typically applied by spraying it directly on the affected plants, covering all surfaces, including the tops and undersides of leaves, stems, and branches.

Which one is good to use?

Both insecticidal soap and neem oil are great for controlling bugs in indoor and outdoor plants, but when deciding which one to use, it is important to consider the nature of the pests you are targeting and the type of plant you are treating.

If the pest is misidentified, choosing an effective pesticide or another management strategy won’t be possible. Explains the University of California Statewide IPM Program. 

Insecticidal soap is a great choice for soft-bodied insects such as aphids, while neem oil may be more effective against a wider range of pests, including mealybugs. However, neem oil can be more expensive than insecticidal soap and may require several applications to maintain control.

Pro Tip: Add a few drops of neem oil to an insecticidal soap to form a stronger effective solution against severe pest infestations.

Both neem oil and insecticidal soap can damage the plant when used in higher concentrations, when applied in temperatures above 90 °F, sprayed in direct sunlight, or when high humidity around the plants prevents rapid drying, warns Clemson Cooperative Extension.

What to know when using a pesticide

Whether using neem oil or insecticidal soap, it’s important to check the label for instructions on the target pests, application rates, and safety precautions. Mix concentrated formulations with water as directed on the product label.

Before applying the solution to the entire plant, test it on a small, inconspicuous area to ensure it doesn’t damage the plant. Wait for a day and check the plant for any signs of damage or discoloration. 

If the plant appears healthy after testing, spray the solution evenly on all parts of the plant, including the tops and undersides of leaves, stems, and branches. Cover the entire plant thoroughly but avoid over-saturating it with the solution.

Final Thought

Using a pesticide should be the last resort in controlling pests on your plants. Check if changing a condition can solve the problem. Keep your houseplants healthy by providing adequate light, water, and nutrients. Further, avoid over-fertilizing or over-watering, as these can attract pests.

When used properly, neem oil or insecticidal soap can protect your plants from damage. However, the products may harm the plants when the label instructions are incorrectly followed.