Neem oil insecticide is often a great solution if insects, mites, or fungi bother your plants. Neem oil is pressed out of the seeds obtained from neem trees. In addition to its use as an organic insecticide spray, it has been used medicinally and in the cosmetics industry. 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. Learn how to make and use a neem oil mixture against certain insects so your plants can thrive.
When 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. Many pesticides can only be used at certain times during the season, but neem oil can be used throughout a planting season. Neem oil is effective any time during a season because it affects insects during all phases of their development.
According to the EPA, neem oil contains azadirachtin, an active compound which interferes with the normal life cycle of insects, including feeding, molting, mating, and egg-laying. Neem oil is used to control 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 extract of neem oil 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.
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.
Diluted liquid soap works as a homemade garden pesticide. It kills aphids and other soft bugs when sprayed directly on pests, as well.
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.
When applied as a preventative measure, neem oil should be applied on a seven- to 14-day schedule according to the manufacturers of 70 percent neem oil. 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 burn, as well.
- Make small batches of neem spray the same day you intend to use it or else your mixture will start becoming gloppy over time.
- Try a peppermint liquid soap as your emulsifier, or add a few drops of peppermint essential oil into the mixture, because many bugs are repelled by the fragrance, as well.
- 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.
Azadirachtin (121701) Clarified Hydrophobic Extract of Neem Oil (025007) Fact Sheet. Environmental Protection Agency.
Cornus Florida. Missouri Botanical Garden.
Juniperus Squamata 'Blue Star'. Missouri Botanical Garden.