How to use neem oil to as a natural insecticide to protect your plants from pests

• Neem oil comes from the pressed fruit of the neem tree, which is native to India and Africa.
• Neem oil has natural insect-repelling properties, making for a useful yet organic insecticide.
• To use on plants, neem oil should always be mixed with water and dish soap.

If you're looking to deal with a houseplant pest infestation without toxic pesticides, you should familiarize yourself with neem oil. For many green thumbs, neem oil is a go-to insecticide that can get rid of hundreds of pests and diseases, including spider mites, aphids, scale, mealybugs, blight, and leaf spot.

Chelsea VanderGraaff, co-founder of the gardening and backyard farming blog Love From Our Backyard, shares her best tips on how to properly use neem oil for your plants.

Important: While neem oil is FDA and EPA approved for indoor use with plants and animals, VanderGraaff cautions against using too much, and those with skin sensitivities should be extra cautious since its potency can cause skin irritation.

What is neem oil, exactly?

Neem oil derives from the evergreen neem tree, native to India and most of Africa. Similar to sunflower and olive oil, neem oil comes from the seeds of the fruit.

"When the fruit and seeds are pressed, oil is released as neem oil, also known as margosa oil," says VanderGraaff. "Neem oil contains azadirachtin, a chemical compound that suffocates and kills harmful pests by interfering with the insect's hormones, thus affecting their ability to grow and lay eggs, then reducing and repelling their ability to feed."

Despite its properties, neem oil mixtures are pet-safe. It also does not harm beneficial insects and pollinators such as bees and earthworms.

When to use neem oil

Unlike many pesticides and insecticides, neem oil can be used during any season, but is most effective during planting season. Since neem oil is a strong natural insect repellent, it is mainly used as a preventative method. VanderGraaff says spraying plants once a day is safe, although most plant parents opt for a once a week spraying schedule.

Note: Neem oil mixture won't typically work on plants with textured leaves, such as velvety Calatheas and fuzzy succulents like Kalanchoe Tomentosa, since these textures allow for pests to crawl throughout the leaves and escape the spray.

How to make and use a neem oil spray

Commercial neem oil spray can often be found at local nurseries, hardware stores, and even big box retailers. However, a homemade mixture is easy to make, plus you'll be able to better measure the dilution and potency of your mix.

What you need

• 1 to 2 tablespoons of raw/pure, cold-pressed neem oil
• Spray bottle
• 1 gallon of warm water
• 1 to 2 teaspoons mild dish soap
• Optional: dish gloves or other protective gloves
• Optional: peppermint essential oil

Instructions

1. Combine the neem oil and water. Add 1 to 2 tablespoons of neem oil to a gallon of warm water. Warm water allows for better emulsification.

2. Add dish soap. Add 1 to 2 tablespoons of mild dish soap. Since oil and water don't mix, adding dish soap helps emulsify the mixture.

3. Add essential oil (optional). Add 6 to 10 drops of peppermint essential oil. The scent of peppermint deters insects. Peppermint dish soap can also be a great way to downsize ingredients.

4. Mix thoroughly. Shake the gallon bottle a few times. The mixture should look slightly cloudy and soapy.

5. Transfer mixture into a spray bottle. Always shake the spray bottle before spraying to mix properly.

6. Lightly spray onto plants. Spray the mixture as much as once a day to once a week during the early morning or evening. Gently rub the mixture on the leaves and stems. Protective gloves are recommended, especially if you have sensitive skin.

7. For severe infestations, spray the plant daily for up to a week. All other plants can be sprayed once per week.

Note: Unopened cold-pressed neem oil has a shelf life of about a year when stored in a cool, dry place. A homemade neem oil mixture is most effective within hours of being made and can last about three to four days stored in a cool, dry place before compounds begin to break down.

Tips for applying neem oil

• Don't drench plans. "A light spray will do," says VanderGraaff. "Less volume of spray and more frequency is better than drenching it once per day since too much may end up blocking the plants' ability to absorb sunlight."
• Avoid direct sunlight. If possible, VanderGraaf recommends avoiding spraying the neem oil mixture on plants, especially those outdoors, during the middle of the day or when the sun is out and strong. Harsh sunlight combined with neem oil can also cause leaves to burn. Spraying during the early morning or evening is recommended.
• Do a patch test. Choose a hardy plant with plenty of healthy leaves to test the neem oil mixture. If brown or yellow spots appear where the mixture was sprayed within 24 hours, this can signify too much sunlight or that the neem oil is not diluted enough.
• Avoid neem oil with certain plants. "Neem oil is fine to use on almost any plant, but I would avoid using it on sprouts, seedlings, or new transplants," says VanderGraaff. "Neem oil can burn plants, and if they're already stressed, weak, or without their own natural oils, the neem oil will be overwhelming."

Insider's takeaway

Neem oil is nature's best alternative to chemical insecticides. Mixing it as a spray with warm water and dish soap allows for an effective preventative method on nearly every houseplant, outdoor plant, and edible crops.

Spraying plants with this mixture regularly, from once a day to once a week, can be a simple solution to avoid pests and even get rid of current infestations. With just a light spray, avoiding direct sunlight, your plants can remain healthy and thrive with the help of this powerful oil.