How to Use Neem Oil as an Organic Insecticide
This Natural Option Is Safe for Plants
Neem oil is an organic solution used as a pesticide against insects, mites, or fungi bothering your plants. It is used medicinally and in the cosmetics industry as an organic insecticide spray. Organic gardeners love that the oil is safe to use: It will not harm humans or animals, and it's safe even for most wildlife since its insecticidal properties are targeted to specific pests that damage garden plants.
You can buy commercial neem oil solutions, but they may be less potent than homemade versions. Read on to learn how to make and use a neem oil mixture against certain insects so your plants can thrive.
What Is Neem Oil?
Neem oil is a naturally occurring pesticide found in seeds from the neem tree with a hundred-plus-year history of controling pests and diseases. The active ingredient in the oil is azadirachtin, which repels and kills pests.
When and Where to Use Neem Oil
Spray neem oil on foliage in the morning or evening when beneficial bugs are dormant and not feeding or pollinating. Avoid using the spray in the middle of the day when the sun and heat could burn the sprayed foliage. You can only use many pesticides at certain times, but you can use neem oil throughout the planting season. Neem oil is effective at any time during a season because it affects insects during all phases of their development.
Neem oil is safe for the environment. If you have a bad infestation, apply the neem oil solution to the stems, leaves (including the undersides), and soil. Microbes and light quickly break down the pesticide in soil, water, and leaves.
What does neem oil do to bugs? According to the EPA, neem oil interferes with the normal life cycle of insects, including feeding, molting, mating, and egg-laying. Neem oil controls hundreds of pests, including whitefly, aphids (pictured below), Japanese beetles, moth larvae, scale, and spider mites. Neem oil is also listed as a miticide because it kills mites, which are not insects but are related to spiders and ticks.
Sprays containing clarified hydrophobic neem oil extract are also used as fungicides against rust, black spot, mildew, leaf spot, scab, anthracnose, blight, and botrytis. Neem oil does not harm birds or beneficial insects and soil-loving creatures, such as bees, butterflies, lady beetles, and earthworms.
What You'll Need
Equipment / Tools
- Garden sprayer
- Spray bottle (optional)
- Protective gloves (optional)
- 1 to 2 tablespoons neem oil, pure or raw form, cold-pressed
- 1 gallon water
- 1 to 2 teaspoons mild dish detergent
Mix the Detergent and Water
Neem oil will not readily combine with water and needs an emulsifying agent, like a mild dish detergent, to effectively mix the oil. Add 1 to 2 teaspoons of dish detergent to 1 gallon of warm (not hot or cold) water in your sprayer. Mix thoroughly.
Add Oil to the Detergent and Water
After you've combined the detergent and water, slowly pour in 1 to 2 tablespoons of neem oil. Mix thoroughly.
Spray the Solution
Spray all plant surfaces (including tops and undersides of leaves) until completely wet and dripping. Use protective gloves to avoid any oily drips.
As a preventative measure, neem oil should be applied to all the plant surfaces on a seven- to 14-day schedule, according to neem oil manufacturers. When applied to control present infestations, apply the oil mixture every seven days.
Tips for Using Neem Oil
- Adding too much neem oil to your mixture may cause leaves to burn if they are in direct, harsh sunlight most of the day.
- Avoid spraying new seedlings with neem, or they could also burn.
- Make small batches of neem spray the same day you intend to use it, or your mixture will become gloppy over time.
- Try a liquid peppermint soap as your emulsifier, or add a few drops of peppermint essential oil into the mixture, because the fragrance also repels many bugs.
- Neem benefits certain trees, as well. Flowering dogwood trees (Cornus florida) are highly susceptible to powdery mildew. Because powdery mildew is a fungus, the fungicidal properties of neem oil make the product effective for fighting this problem.
- Blue Star juniper (Juniperus squamata Blue Star) can succumb to infestations of spider mites. Take advantage of neem oil's miticidal properties to kill spider mites on the plant.
- Spraying Colorado blue spruce trees (Picea pungens) with neem oil can work as an insecticide against Cooley spruce gall adelgid and aphids.
Neem oil. National Pesticide Information Center. Oregon State University.
Azadirachtin (121701) Clarified Hydrophobic Extract of Neem Oil (025007) Fact Sheet. Environmental Protection Agency.
“Less Toxic Insecticides.” Clemson University, South Carolina.
Cornus Florida. Missouri Botanical Garden.
Juniperus Squamata 'Blue Star'. Missouri Botanical Garden.