Insecticidal soap - Pests it Manages, Pros & Cons, How to Use

Insecticidal soap is a simple spray made from the potassium salts of fatty acids. It works on contact — coating soft-bodied insects and drying them out — and it's one of the safest sprays you can reach for in a veggie patch.

Pests it manages:

• Aphids
• Thrips
• Whiteflies
• Mites (including two-spotted mite)
• Mealybugs

It only works on soft-bodied pests, and only where the spray actually lands — so good coverage is everything.

How to use it:

1. Mix to the label, or make your own with a little pure soap (not detergent) in water.
2. Spray directly onto the pests, tops and undersides of the leaves. It only works while wet.
3. Spray in the cool of the day to avoid burning the leaves.
4. Repeat every few days until the pests are gone.

The good:

• Very low toxicity to people, pets and the environment.
• Cheap and easy to use.
• Safe on most edible crops.

The catch:

• Only works on direct contact — no lasting protection once it dries.
• Can scorch tender or stressed plants, so test a leaf first.
• Won't touch hard-shelled pests like beetles.

Along with neem oil, insecticidal soap is one of our first picks for aphids and other soft-bodied pests. For the bigger picture, see our guide to managing pests safely.

Plan your patch: our free planting calendar shows what to plant now where you live. Ready to grow? Browse our raised garden beds or build your own with the garden bed builder.

Image: CosyCobra, CC BY-SA 4.0, via Wikimedia Commons.