Problems with spider mites? Give your plants a bath with insecticidal soap! Made from a simple soap solution, insecticidal soap is a greener, more eco-friendly approach to insect problems in the garden and on houseplants. You can buy insecticidal soap in a ready-to-use spray or make your own using this simple recipe.
Insects Affected by Insecticidal Soap
Insecticidal soaps work by disrupting the cell membranes and dissolving the natural waxy coatings found on soft-bodied insects including:
- Immature leafhoppers
- Mealy bugs
- Spider mites
- Immature white flies
- Eggs and pupae of other insects
Eco-Friendly Advantages of Insecticidal Soap
If made and used correctly, insecticidal soap is more eco-friendly than traditional insecticides since it:
- Has no residual effect.
- Only works when coming in direct contact with soft-bodied insects.
- Is biodegradable and nontoxic (if the right soap is used).
- Kills target insects without harming birds or hard-bodied beneficial insects such as predatory wasps, lacewings, and pollinating bees.
How to Apply Insecticidal Soap to Plants
Follow these tips when applying insecticidal soap to plants:
- Avoid Sensitive Plants: Some plants are known to be sensitive to insecticidal soap sprays. In particular, be careful around ferns, succulents, ivy, palms, lantana, azaleas, some tomatoes, and plants with waxy leaves. Also, avoid spraying tender new growth or blooming plants with insecticidal soap.
- Shake Well: Shake the insecticidal soap solution well just before spraying to disperse the soap throughout the water.
- Test First: If this is your first time using insecticidal soap, conduct a test spray on an inconspicuous branch to make sure your plant can tolerate it. Wait 24 hours and look for burned or scorched spots on the leaves before proceeding. If the insecticidal soap damages the plant, dilute it the in half and try again. If it still burns, you probably need to avoid spraying that plant.
- Stressed Plants: Before treating with insecticidal soap, make sure your plants have been watered and aren’t under stress. Never spray wilted plants.
- When to Spray: The best time to spray with insecticidal soap is in the early morning or evening when temperatures are cool and plants are shaded, since the spray will stay wet longer and be more effective.
- Apply Thoroughly: Many soft-bodied insects hang out on the undersides of leaves. Be sure to spray both the tops and bottoms of leaves with insecticidal soap, as well as the stems. Remember that insecticidal soap will only work on the bugs that actually get wet. Since the soap is harmless once it dries, any unsprayed bugs will survive the treatment.
- Repeat Treatment: Insect infestations often require a second treatment with insecticidal soap in a week or so, and possibly even a third. For severe problems, you may want to apply several days in a row, then follow up a week or two later. Keep in mind that the spray stops working once it dries and completely washes away in rain.
- Control Houseplant Insect Pests Safely with Insecticidal Soap (Iowa State)
- How to Make Homemade Insecticidal Soap for Plants (article)
- Ortho EcoSense Brand Insecticidal Soap (scotts.com)
- Organic Pest Control (video)
- Organic Gardening 101 (article)
- Is Pyrethrum a Safe Organic Pesticide? (article)
- How to Use Neem Oil in Your Garden (article)
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