Neem Oil For Plants Guide: When And How To Apply Neem Oil Products

Last Updated September 12, 2023 By Bella Zinti

Home » Plants » Neem Oil For Plants Guide: When And How To Apply Neem Oil Products

Gardeners and enthusiasts are constantly looking for sustainable and effective solutions in the quest for healthy and vibrant plant life. Amidst the sea of synthetic chemicals and complex treatments, there emerges a humble yet mighty contender: neem oil. With its centuries-old legacy as a traditional remedy in various cultures and now gaining recognition in modern gardening practices, neem oil has proven to be a versatile and eco-friendly asset for nurturing plants.

Neem oil is not a new discovery; its history can be traced back to traditional practices in India and other parts of Southeast Asia, where the neem tree has long been revered for its medicinal and pesticidal properties. What sets neem oil apart is its exceptional ability to strike a balance between plant protection and ecological preservation. Gardeners and plant enthusiasts are embracing neem oil as a natural alternative.

Thankfully, neem oil products have been proven to be just as effective at killing pests and keeping plants healthy - without harming the soil or killing beneficial insects. Keep reading to learn how to use neem oil to target pests bothering your plants!

What Is Neem Oil?

Neem oil is an effective, natural pesticide and fungicide that is produced by pressing the fruits, seeds, and barks of the Azadirachta indica tree - more commonly known as the margosa tree, neem tree, or Indian lilac tree. This tree grows in South Asia and parts of Africa.

There are multiple ways to extract neem oil, and each method has its specific uses. Cold-pressed neem oil is the most effective type for indoor and outdoor plants, producing a strong concentration of the azadirachtin compound. This neem oil concentrate should be diluted before use, and it is commonly sold as both a concentrate and as a pre-diluted product.

How Does Neem Oil Work?

The compounds contained in neem oil have long been used for skincare and medicinal applications but can also be used to control pests and eliminate fungal diseases. Neem oil works to control insects in multiple ways, making it effective against various pests. It can:

  • Interrupt reproductive cycles
  • Inhibit feeding processes
  • Disrupt insect growth
  • Repel further insect infestation
  • Serve as a contact insecticide, killing harmful insects on contact

When Should Neem Oil Be Used?

When you notice the first signs of pest activity or fungal infection, it's a good time to apply neem oil. Early intervention can prevent the problem from escalating and spreading to other plants. However, you can also apply neem oil as a preventive measure before pest or disease issues arise. This becomes particularly crucial in the growing season when conditions are optimal for pests and pathogens to thrive. Regular preventive applications can create a protective barrier on plants, deterring pests and reducing the likelihood of disease development.

Apply neem oil in the cooler timeframes of the day, like early morning or late afternoon, to mitigate the potential for leaf burn caused by sunlight interacting with the oil. However, neem oil should not be used in the middle of the day. This precaution is necessary because the potent compounds present in neem oil, when combined with direct sunlight, have the potential to cause plant burns.

For gardeners, neem oil has additional benefits over other pest control methods. Whereas many pesticides can only be applied at certain times, neem oil can be used at any point of the planting season.

What Pests Does Neem Oil Protect Against?

Neem oil has been proven to be an effective natural pesticide against common garden pests, indoor pests, and insects that are difficult to manage through chemical pesticides. So far, neem oil has been reported to eliminate over 170 insect species. Some of these include:

Garden Pests- Garden pests, such as the potato beetle, corn beetle, whitefly, spotted cucumber beetle, corn earworm, flea beetle, Japanese beetles, and cabbage looper.

Houseplant Pests- Houseplant pests, such as fungus gnats, thrips, mealybugs, spider mites, and root-knot nematodes.

Persistent Pests- Persistent pests, such as aphids, termites, and multiple types of caterpillars.

What Fungal Diseases Does Neem Oil Protect Against?

Neem oil is renowned for its antifungal properties, making it a valuable tool for preventing and managing various fungal diseases affecting plants. Some of the fungal diseases that neem oil can help protect against include:

Powdery Mildew

Powdery mildew is a fungal disease that appears white powdery on plant leaves, stems, and even flowers. It thrives in environments of high humidity and poor air circulation. Neem oil's antifungal properties disrupt the growth and reproduction of the fungi responsible for powdery mildew. Regular applications of neem oil create a protective barrier on plant surfaces, making it harder for the spores to germinate and spread.

Black Spot

Black spot stands as a prevalent fungal infection that impacts not only roses but also various other plant species. It results in circular black spots with fringed edges on the leaves, causing them to turn yellow and eventually drop. Neem oil's antifungal compounds inhibit the growth of the fungus responsible for black spots, helping to prevent the spread of the disease. It also has a protective effect, making it difficult for the spores to establish on the plant's surface.


Rust manifests as a fungal ailment, presenting itself in the form of rust-colored or orange spots on the leaves and stems of plants. It often causes leaves to become distorted and can weaken the plant over time. Neem oil's antifungal properties hinder the growth of rust-causing fungi by disrupting their cell membranes and metabolic processes. Regular neem oil applications can reduce the occurrence of rust and minimize its impact.


Anthracnose refers to a group of fungal diseases that lead to dark lesions on leaves, stems, and fruits. It can cause defoliation, stunted growth, and yield reduction. Neem oil's antifungal components interfere with the life cycle of the fungi responsible for anthracnose, preventing spore germination and penetration into plant tissues. This helps reduce the severity of the disease.

Downy Mildew

Downy mildew is a fungal infection characterized by the emergence of yellow or brown patches on the upper leaf surfaces, often accompanied by a white, velvety growth on the undersides. Neem oil's antifungal properties work against the pathogens causing downy mildew by disrupting their cell membranes and reproductive processes. Applying neem oil can impede downy mildew growth and prevent its spread.

Botrytis (Gray Mold)

Botrytis, commonly known as gray mold, is a fungal disease affecting many plants, causing grayish mold and decay. Neem oil's antifungal compounds target the fungal spores and mycelium of Botrytis, inhibiting their growth and preventing the disease from advancing. Consistent application of neem oil contributes to upholding plant well-being and lowering the likelihood of gray mold formation.

Leaf Spot

Various fungi cause leaf spot diseases and result in dark, round lesions on plant leaves. Neem oil's antifungal properties disrupt the cell membranes of these fungal pathogens, hindering their growth and preventing them from causing extensive damage. Applying neem oil to susceptible plants can help protect them from leaf spot diseases.

Damping Off

Damping off is a fungal disease that targets young seedlings, resulting in their wilting and eventual collapse. Neem oil can be used as a preventive measure by treating seeds or young seedlings with a neem oil solution. The antifungal properties of neem oil create an unfavorable environment for the fungal pathogens responsible for damping off, helping young plants establish themselves more successfully.

spray plant

Which Plants Should You Use Neem Oil On?

With its inherent gentleness and natural attributes, neem oil becomes a valuable asset in your plant care toolkit. Its versatility makes it a beneficial solution for an extensive array of both indoor and outdoor plants. Here's a look at which plants can particularly benefit from the application of neem oil:

Ornamental Plants: Neem oil can be safely used on ornamental plants such as roses, dahlias, lilies, and other flowering varieties. It helps keep common pests like aphids, mealybugs, and spider mites at bay while nourishing the plants' overall health.

Fruits and Vegetables Edible plants like beefsteak tomatoes , peppers, squash, and strawberries can benefit from neem oil's protective properties. By reducing the presence of pests and preventing fungal diseases, neem oil contributes to healthier produce without leaving harmful residues.

Herbs: Neem oil is a great choice for herbs like basil, mint, and oregano. These culinary delights can sometimes fall victim to pests, and neem oil provides a safe and effective way to address such issues without compromising the quality of your herbs.

Houseplants: Indoor plants such as peace lilies, spider plants, and succulents can also enjoy the advantages of neem oil. Its gentle nature ensures it won't harm your indoor greenery while effectively deterring pests and maintaining a vibrant appearance.

Shrubs and Trees: Neem oil can be used on shrubs and trees, including evergreens and deciduous varieties. Whether you're dealing with scale insects, leafhoppers, or powdery mildew, neem oil's protective layer can help shield your larger plants from various challenges.

Garden Flowers: Flowers like marigolds, petunias, and sunflowers can thrive with the application of neem oil. Consistent application can result in plants that are healthier and possess fortified defenses against pests and diseases.

Indoor Gardens: If you have a hydroponic or indoor gardening setup, neem oil can be a useful tool. It's less likely to disrupt the delicate balance of indoor ecosystems while effectively managing common issues.

What Plants You Avoid Using Neem Oil On

While neem oil is generally considered safe and effective for many plants, certain species might be sensitive to neem oil or could potentially experience adverse effects from its application. For this reason, there are certain plants where it is inadvisable to use neem oil insecticide. It's advisable to conduct a patch test on a discreet portion of the plant before applying neem oil to the entire plant.

Here are some plants that are often recommended to avoid using neem oil on or to use it with caution:


Herbs such as basil, caraway, cilantro, dill, marjoram, oregano, parsley, or thyme have delicate and sensitive foliage that can be adversely affected by oil-based products like neem oil. Neem oil might clog the stomata (leaf pores), inhibiting the herb's ability to transpire and perform photosynthesis. This could lead to stressed and weakened plants.

Sensitive Foliage

Neem oil application should be avoided on plants with delicate leaves, including arugula, lettuce, peas, and spinach. If not properly diluted or applied, neem oil can sometimes cause leaf burn on plants with delicate foliage. Delicate leaves have thinner and more sensitive tissues that might be more susceptible to damage from concentrated neem oil solutions. The oil can block the stomata (leaf pores), hindering transpiration and photosynthesis leading to stressed and discolored leaves.

Newly Transplanted Seedlings

Young seedlings recently transplanted might be more sensitive to neem oil. Applying neem oil to stressed or delicate seedlings can potentially cause damage. It's best to allow seedlings to establish themselves before introducing neem oil.

spray garden plant

How Can Neem Oil Be Applied?

There are multiple ways to apply neem oil, each affecting a different part of the plant.

Drenching the Soil

Use diluted neem oil or neem cakes dissolved in water to drench the soil. This approach treats neem oil as a systemic insecticide, where the compounds are taken up by the plant's vascular system. Any sucking insect pests will be exposed to the neem oil as it spreads throughout the entire plant.

Neem Oil Spray

Dilute neem oil concentrate in a spray bottle with water and then spray neem oil mixture onto the plant leaves or the soil. Use a small amount of liquid soap to help the water and neem oil incorporate. You can make your own foliar spray or purchase a pre-made neem oil spray. Avoid spraying fruit trees or vegetables when harvest is expected within a week, as the neem oil can cause the produce to take on a bitter flavor.

Hydroponic Application

Neem oil can also be used in hydroponic systems to manage pests and diseases in a controlled environment. However, you should ensure the neem oil solution is appropriately diluted and doesn't clog the system.


Is Neem Oil Safe For Beneficial Insects?

Using neem oil for plants helps support beneficial bugs, such as ladybugs, predatory mites, honey bees, butterflies, and other pollinators. It does not appear that neem oil will kill beneficial insects as long as they are not directly sprayed with the neem oil. Earthworms appear to remain unaffected when neem oil is applied as a soil drench.

Is Neem Oil Safe To Use Around Pets?

The utilization of neem oil in proximity to pets and livestock is considered safe. However, neem oil is potentially toxic to fish, amphibians, and other aquatic organisms.

Is neem oil harmful to beneficial insects?

Neem oil is considered less harmful to beneficial insects compared to synthetic chemical pesticides. However, it can still impact some beneficial insects, so it's best to apply neem oil when beneficial insects are less active, such as early morning or late evening.

Can neem oil be used in hydroponic systems?

Yes, neem oil can be used in hydroponic systems, but care should be taken to ensure proper dilution and prevent system clogging. Hydroponic gardeners should be cautious about potential interactions with their setup.

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About the author

Bella has a Bachelors degree in interior design, is a master gardener. She designs nourishing outdoor & indoor spaces guided by the practice of Feng Shui.