What is Neem Oil? 10 Explanation Points

Neem oil is a natural pesticide that contains azadirachtin, which has been used for hundreds of years to control pests and diseases in plants. Lucky for you, a science degree isn’t required to know how to use it!

As a horticulturist, I have found ways to use plants naturally to control pest infestations and diseases. Organic pest control has always been my favored method over the use of chemicals. It is also far safer to use in the environment.  

I’m going to share with you the information I know about neem oil, any dangers to look out for when using it, how to use it as a homemade pesticide, and what plants not to use it on.

neem oil bottle, leaves, bark and fruit

Table of Contents

Is Neem Oil a Natural Pest Repellent?

The purest form of this oil works by interrupting the hormones of pests. When the hormones are in contact with the active ingredient of neem oil insecticide, it affects their breeding, feeding, and growth.

It sounds brutal, but it will happen in nature anyway, so don’t classify yourself as a murderer too soon!

After the neem tree has borne the fruit and seeds, they are then pulverized, and the oil containing the compound Azadirachtin is then extracted and mixed with a solvent such as alcohol or water.

The bi-product of this extraction process is often used in neem cakes. These contain the bark, seed husks, and plant matter. These are high in NPK (Nitrogen, Phosphorus, Potassium) and can be used as a fertilizer for your plants.

Depending on the extraction method, you will find differences in the strength of the oil, and the purest extract will give you the best chance at fighting off a variety of pests such as mites, beetles, and larvae.

Can I Make My Own Oil? 

Making this oil insecticide spray is easy, and to begin, you will need cold-pressed neem oil, liquid soap, a gallon (3.7l) of warm water, and a foliar spray bottle.

Here are the steps to making your spray-

  • Pour 1 gallon (3.7l) of warm water into the spray bottle
  • Add one teaspoon of liquid soap. It is essential to take this step first to create an emulsifier to add to the neem oil.
  • Add two tablespoons of neem oil to the warm soapy water.
  • Shake the bottle before using it.

I stick with this ratio (2 Tablespoons per 1 gallon (3.7l)). This oil is not easy to access and proves strong enough to have an effect. It won’t last for long after it has been diluted, so only make the amount you will use, or you will be wasting it.

After you have sprayed the foliage and there is some of the mixture to spare, you can spray the soil of the ground where the plants are too. This will prevent waste and help with any en-route pests to your plants.

When is Neem Oil Best Used?

Use this oil in the early morning and the evening at any time of the year. It’s best to avoid using it in direct sunlight or in the middle of the day. As you can imagine, hot oil on the plants’ leaves will result in burning and do more harm than good.

Apply the oil as a foliar spray or soil drench once a week until there are no signs of pests returning.

Try to refrain from using it when the plant is young or showing signs of stress, for example, wilting leaves or sun scolding. Your plant is already low on energy by this point, so it’s best to leave the amount of energy out of the plant.

You can use the natural pesticide at the beginning of the growing season as it is proven to have the best results on new plant growth.

foliar spray bottle with plants in clay pots in living room

How Shall I Spray This Oil?

Organic neem oil can be used to treat a houseplant’s leaves or the soil. Both methods take time, so don’t expect to see the culprits wither or run away before your eyes!

When spraying the plant leaves, ensure you spray the front and back part of the leaves and the entire plant as often there can be hidden pests that lay eggs on the undersides.

Apply the natural solution at least once a week, as the organic oil doesn’t last long when exposed to the environment. Spray it until the bugs have disappeared. Depending on the severity of the infestation this might take a few weeks or months. 

man spraying plant leaves in sunlight

Can Plants Consume Neem Oil?

If you use this oil as a soil treatment, pour the solution on the ground or soil where the plant is, and the plant will take it into its vessels; any pests feeding on your plant will digest the compounds.

Suppose you must treat plants used for consumption. Refrain from using the oil two weeks before harvesting. It has a bitter taste and can affect the flavor of your produce.

person holding soil in their two hands

What Can This Oil Kill?

As a gardener, you will undoubtedly face some of the most stubborn pests, but luckily, this oil has proven effective on most of these.

One common pest in my garden is the mealybug which simply hops from one plant to another, taking its whole family with them. I have been using it for the past two months and have seen a massive reduction in their numbers.

Some other pests that this oil will control are Fungus Gnats, Thrips, Japanese beetles, White flies, Moth Larvae, Corn earworm, Potato Beetle, Flea beetle, spider mites, and Cabbage beetle, just to name a few.

gnat on dark green leaf

One stubborn pest we don’t see unless we uproot the plant is root-knot nematodes which can cause horrific damage to plants. It will prevent the larvae from hatching, and using extracts of the neem kernel will help fight the root nematode.

Reportedly, it also disrupts the feeding cycle of over 170 insects and is toxic to aphids, termites, and various caterpillars.

Can Neem Oil Control Diseases?

Neem oil is not limited to repelling garden pests. It works to control diseases commonly found in plants. Fungal infections such as powdery mildew, black spot, rust, sooty mold scabs, anthracnose, and leaf spot are all affected when in contact with neem oil.

When a fungal disease is present in your plants, the spores will often spread in the air; this oil stops the germination of these spores and prevents the spores from entering the leaf’s tissue.

Although it isn’t an instant cure for a fungal disease, it will stop it from spreading. So you may need to remove leaves or diseased branches to help your plant.

Are There Any Dangers? 

The EPA (Environmental Protection Agency) has reported this oil is safe for pets and indoor plants and practically non-toxic.

It is so potent, it can cause an adverse reaction in someone with sensitive skin or eczema. If ingested, Neem oil can cause vomiting, metabolic acidosis, liver damage, and brain ischemia.

I’m no doctor, but these sound pretty terrible. When using this oil, keep it away from children, pregnant women, and other food items when storing. My neem oil recently came in bottles resembling cake-making essences, so they could be easily confused.

Do All Plants Like it?

array of herbs rosemary thyme
Don’t use Neem Oil on Herbs

You should NOT use neem oil on herbs such as basil, caraway, cilantro, dill, marjoram, oregano, parsley, or thyme. Plants that contain delicate leaves, such as lettuce, arugula, peas, and spinach, should be dealt with care. Their leaves are tender, and the oil may cause burning of the leaves.

For plants that don’t have a smooth surface and contain needles, fur, deep groove, or any other texture, neem oil will be ineffective. Because of the textured surface, it creates small areas where the bugs can bury into the leaves to hide and escape the oil.

Always check a small area of the plant before spraying it entirely.

About Neem Oil

neem tree with fruit

Neem tree oil comes from a pulverized seed grown on the South Asian evergreen neem tree Azadirachta indica. Known in the regions of India and Africa as the ‘cure of all ailments’, the vegetable oil is commonly found in soaps and skincare products around the globe.

Not only do this oil’s products provide skin care and medicinal solutions they are widely used as an organic method of pest control on indoor and outdoor plants.

It doesn’t hold the best fragrance compared to other extracted oils and smells similar to garlic or sulfur. It’s a yellowy-brown color and has a bitter taste. Despite these unpleasant features, it is one of nature’s most beneficial oils available.


What is neem oil used for?

Neem oil controls and kills pests on plants such as Fungus Gnats, Thrips, Japanese beetles, White flies, Moth Larvae, Corn earworms, Potato Beetle, Flea beetle, Cabbage beetle, spider mites, and mealybugs.

Other neem oil products are used for skin, hair, and nail care, making them versatile when used correctly.

What are the side effects?

Serious side effects from ingesting neem oil include vomiting, metabolic acidosis, liver damage, brain ischemia, coma, loss of consciousness, and death.

Neem oil and bark are unsafe when digested during pregnancy and can cause miscarriage.

What is neem oil, and is it safe?

Neem oil is a natural extraction from the evergreen neem tree Azadirachta indica, native to India. Organic neem oil has been deemed safe to use in the US by the Environmental Protection agency.

It is safe for ornamental plants and non-toxic to birds, mammals, and bees.

Can neem oil be applied directly to skin?

Applying neem oil directly to the skin is safe but should be tested on a small area first. Due to its potency, it is best to mix neem oil with water or soap before using it liberally. If you suffer from sensitive skin or eczema, you should take caution as it may cause adverse reactions.

Does neem oil affect beneficial insects?

Luckily, Neem oil does not impact beneficial insects such as ladybugs, predatory mites, butterflies, and honey bees if not sprayed directly.

Neem Oil Is The Best Organic Pesticide

It is a great organic alternative to many pesticides containing chemicals and effectively controls insects taking over your plants.

Applying neem oil as a foliar spray can assist in combating fungal diseases that occur on indoor and outdoor plants. Neem oil doesn’t harm birds, honey bees, butterflies, or other beneficial insects unless sprayed directly.

Care should be taken when storing and handling neem oil, as it can be toxic to humans and cause adverse reactions.

Switch to Organic Solutions and Protect the Environment

I have been using this oil on my greenhouse plants for the past two months, and I have seen a considerable reduction in the population of mealybugs taking over.

It’s great to share with you the information I have found out about neem oil. I hope more gardeners will convert to using organic insecticides on their plants so we can reduce the risk of chemicals in our waterways. Also to prevent wildlife from being in danger of toxic substances.

Are you interested in finding more organic solutions used in gardening? Check out our full collection of houseplant tips for more cool plant care info! 

Photo of author
Alex Tinsman
An avid plant and flower lover! Ever since he was little, plants, flowers, and shrubbery of all kinds filled his life. Alex credits this fascination with nature's beauty to his mother and grandmother who were - and still are - dedicated gardeners. It's now Alex's mission to pass that same love for plants onto others and show them it's as easy as pie to bring nature inside.

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