What Are The Safety Hazards Of Using Neem Oil On Plants

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Neem oil is made from the oil of the seeds of the neem tree (Azadirachta indica), which is native to Sri Lanka, India, and Burma. 

The oil contains Azadirachtin and has been safely used as an insecticide in its native lands for hundreds of years. 

Safety Hazards of Using Neem Oil on PlantsPin

In the past few decades, Neem oil has also become very popular among gardeners in the United States and worldwide because it is considered less toxic and less hazardous to beneficial fauna and the environment. 

Even so, some safety hazards are inherent in using any insecticidal product. 

Although Neem oil is fairly harmless to mammals, birds, and beneficial insects such as bees, it can cause harm to fish and aquatic animals. If used incorrectly, it can pose other dangers. 



In this article, we discuss the safety hazards of using neem oil. Read on to learn more.

Neem Oil For Plants: How To Use It

How Can Neem Oil Be Harmless To Bees? 

According to several studies, including one conducted by the University of California, Neem oil is only moderately toxic to bees, and its effects can be mitigated by applying it only very early in the morning or late in the evening when bees are not present. 

Neem oil works by interfering with an insect’s hormone system using its active ingredient, azadirachtin, which hinders its ability to grow and lay eggs.

So even with these precautions, beekeepers beg to differ with the conclusions of these studies. 

They assert that even with these precautions and others, such as refraining from using Neem oil while plants are flowering, products containing Neem can still cause bees to suffer from “the anti-feeding effect.” 

Furthermore, beekeepers assert that when Neem oil is used as a soil drench and is present systemically in plants, it contaminates pollen gathered by bees. 

When the bees carry this pollen back to the hive, it negatively impacts the entire colony. 

For these reasons, beekeepers recommend using pollinator-friendly alternatives, including:

  • Predatory and beneficial parasitic insects
  • Physical barriers such as garden nets
  • Vigilant garden care practices
  • Bacillus thuringiensis (Bt)
  • Insecticidal soap spray
  • Companion planting
  • Essential oil sprays

…to control insects and caterpillars. Instead of using Neem oil to control fungi, choose Bacillus subtilis. 

Applying these alternatives in the early morning or late evening hours will help make them even safer for bees. Never spray any insecticidal product when bees are present.

Precautions For Self-Protection When Spraying Neem Oil

Even though Neem oil is considered safe for humans, breathing it, ingesting it, and getting it on your skin and eyes should be avoided. 

Whenever you use Neem oil mixture or apply any insecticidal product, you should: 

  • Wear gloves, long sleeves, and pants. Excessive amounts of Neem oil (chemicals) on your skin can cause dermatitis and be harmful if absorbed through your skin.
  • Avoid spraying on windy days. You risk having overspray damage to unintended recipients, and you lose a lot of product to the wind. 
  • Wear eye protection. Getting Neem oil in your eyes can cause irritation or even damage. 
  • Wear a mask. Inhaling Neem oil can irritate the airways.

Wash up after application. Even with these precautions, it’s better to be safe than sorry. When you are finished applying Neem oil to your plants, wash your hands, face, and forearms. 

Excessive Amounts Of Neem Oil Will Damage Plant Leaves

Using too much Neem oil or applying the spray when the sun is shining brightly can cause burn marks on plants’ leaves. 

Spray a uniform amount lightly over your plants. Include tops and undersides of leaves and stems, but don’t leave the plant dripping wet. 

Apply the product early in the morning before the sun gets too hot or late afternoon.

Young & Delicate Plants Can Be Damaged By Neem Oil

No matter what type of plant you wish to treat with Neem oil, it’s a good idea to do a spot test before treating the entire plant. Spray a small section of the plant and wait 24 hours to see how the plant responds. 

Very young plants and those with delicate foliage may be burned or killed by the product. 

Apply Neem Oil Spray No More Than Once A Week

To avoid overdosing on your plants, limit applications of Neem oil spray to once every seven days. 

Follow the directions given on the product label to apply Neem oil spray to outdoor plants. Houseplants may also benefit by having their leaves wiped with a light Neem oil solution every week.

Related: Understand Fungus Gnats – Control Them with Neem Oil

Keep Your Neem Oil Spray Light To Avoid Harming Your Plants

You can easily and affordably make a safe 0.5% Neem oil spray by combining a teaspoonful of horticultural Neem oil, half a teaspoon of liquid soap, and a quart of warm water in a spray bottle. 

Shake the mixture thoroughly, and use it right away. This mixture can be used to spray plant leaves weekly, and it is safe to use as a soil drench twice a month if you have a problem with pests like aphids, whiteflies, spider mites, mealybugs, Japanese beetles, and thrips. 

It also works well with fungal infections and other common plant problems, including black spot, rust, anthracnose, blight, and powdery mildew.

Once your problem has been resolved, you can continue using this mild solution monthly (spray and soil drench) as an insect pest repellent and fungal growth preventative treatment. 

The mixture is most effective when used immediately after mixing. After a few days have passed, it will no longer be effective. 

It’s also worth noting that rain will wash off Neem oil spray, so it should be reapplied after heavy rain. Allow plants to dry before reapplying. 

Wash Fruits & Veggies That Have Been Treated With Neem Oil

Even though it is safe to apply Neem oil to fruit and vegetable crops right up to the day of harvest, you should wash the fruits and veggies you gather before you eat them. 

Consuming large amounts of Neem oil could cause symptoms such as: 

  • Rapid breathing
  • Drowsiness
  • Vomiting
  • Seizures
  • Fainting
  • Coma

If these symptoms occur, you must seek medical treatment because there is no antidote, and the symptoms won‘t just wear off. Gastric lavage (stomach pump) is the only treatment. 

How Safe Is Neem Oil? 

When used correctly, Neem oil can have very effective long-term results. Even so, it has been banned in Canada because of the potential safety hazards inherent in misuse. 

It is very important to use the minimal amount of Neem oil needed to effect results; apply the product carefully and at the right time of day. And dispose of any unused product responsibly to avoid contaminating waterways. 

Neem oil acts slowly on insects, so it may seem safe for some beneficial fauna. It can take as long as two weeks for Neem oil to affect results against pests or harm pollinators and predatory insects. 

Indeed, applying it reasonably and carefully timed can make it safer, but it is not entirely safe for bees, butterflies, ladybugs, praying mantises, and other garden helpers. 

As with any pesticide, using Neem oil should be one of your last resorts, not your first choice. 

Preventing pest infestation through vigilant garden care, partnering with beneficial garden fauna, and other entirely natural solutions can go far toward keeping your garden free of pests.

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