Written By Lara Wadsworth

As more gardeners turn to natural and organic gardening solutions, it's no surprise that neem oil has become the go-to solution for pest and disease control. This centuries-old plant-based remedy has long been used to fend off a wide range of garden pests and diseases, without the harsh chemicals. But what exactly is neem oil? Is it safe to use around your veggies, pets, and pollinators? And how do you use it effectively? Don’t worry, we’ve got you covered. This guide breaks down everything you need to know about neem oil for plants–including how to apply it, what pests it treats, and common questions about its use in home gardens.

What is Neem Oil?

Neem oil is an oil derived from the neem tree (Azadirachta indica), which is native to Burma (Myanmar), Sri Lanka, and India. This oil typically contains two main ingredients: Azadirachtin and hydrophobic neem oil. Azadirachtin is made from the seed of the Neem tree and is known to kill, repel, and disrupt insects' lifecycles. Commercial pesticide manufacturers have isolated this compound and include it in other products intended to disrupt insect hormones.

The other ingredient is clarified hydrophobic neem oil. This is the main ingredient that you are buying at a typical garden store. This is the active ingredient in Bonide Captain Jack's Neem Oil Spray. The University of New Hampshire states that hydrophobic neem oil “kills insects by suffocation, covering their bodies with oil that blocks their breathing openings. It is most effective against immature insects.” The best part is that it doesn’t harm plants. In very rare cases, it can cause burning. But, as long as you apply the oil properly (see below), you should have no problem with this.

What is Neem Oil Used For?

Neem oil is used in organic gardens for pest and disease control purposes. Hydrophobic neem oil is fantastic at preventing young insects from reaching maturity and even preventing the spread of fungal spores such as powdery mildew.

With proper use, neem oil spray effectively controls:

• Aphids
• Mites
• Fungus
• White Flies
• Beetle Larvae
• Squash Bugs
• Mold
• Fungus Gnats
• Caterpillars
• Lacebugs
• Leaf Hoppers
• Leafminers
• Mealy Bugs
• Thrips

It is important to note that neem oil cannot cure a plant that has already experienced stress, but it can prevent pest and disease pressures from worsening. Therefore, it is best used as a preventive and first-line defense rather than an after-the-fact cure.

How to Apply Neem Oil to Plants Effectively

The most important thing to remember when using Neem oil is that in order for it to be effective, it needs to cover all surfaces of the entire above-ground plant. Simply spraying a little on top and walking away will do nothing. As described above, the oil works by essentially suffocating the bugs. In order to do that, it needs to coat any bugs you see (or don’t see). The same goes for using it for fungal control. The early stages of fungal diseases like powdery mildew are nearly imperceptible, but the neem oil can still effectively control them if sprayed regularly. A 7-day schedule is recommended at the first signs of damage or disease. Once under control, cut back to a 14-day schedule to maintain coverage.

When to Apply Neem Oil

Neem oil is best applied frequently for the best results. However, users should not apply it just before or after rain showers, as this decreases its effectiveness. It may be applied preventively, or as a treatment once pest or disease damage is identified. Captain Jack’s Neem Oil spray may be applied up to the day of harvest, just be sure to wash your produce before consuming. Neem oil is an organic pest control method. However, many producers, including Bonide Captain Jack’s Neem Oil spray, are not certified for commercial use by OMRI because the product is intended for use by home gardeners.

How to Dilute Neem Oil (If Needed)

Neem oil is typically available as a concentrate or ready-to-use spray. The ready-to-use spray does not need to be altered before use. Concentrates should be diluted with water. Start by adding about 0.5 teaspoons of dish soap to a quart of water. This step is necessary to allow the neem oil to integrate. Once the soap and water are mixed, add up to 1 teaspoon of concentrated neem oil. Use a spray bottle for easy application.

Tips for Preventing Leaf Burn

To prevent burning, avoid spraying on newly transplanted or water-stressed plants. For the most effective results, use neem oil for pest control by applying the spray in the morning or evening hours, as this will minimize the potential for leaf burn. If you are using a neem oil concentrate, be sure to dilute it as directed to prevent excessive application.

How Often to Spray

Apply neem oil to flowers, vegetables, and herbs every 7-14 days. During signs of visible damage or stress, apply every 7 days. Once plants begin to improve, you may reduce the frequency of neem oil application to every 14 days.

Whenever using neem oil, be sure to follow all directions provided by the manufacturer. This typically includes wearing gloves, spraying on a non-windy day, and avoiding spraying directly into water sources like ponds and lakes. While neem oil is sourced from natural ingredients, it is an insecticide, fungicide, and miticide. Store out of reach of children.

Neem Oil FAQ: Safety, Usage, and More

What happens if you ingest neem oil?

For clarified hydrophobic neem oil without azadirachtin, there are usually no adverse effects as the body metabolises it as if it were any other edible oil. It mostly gets passed through your system within 24 hours. For neem oil sprays containing Azadirachtin, contact a poison control center or doctor for directions. Always follow emergency instructions as indicated on the neem oil container. The dose of exposure will greatly determine the appropriate treatment response. Neem oil is generally a very safe product for use in the home garden.

Does neem oil cause cancer?

The science suggests that no, neem oil doesn’t cause cancer, even after long-term exposure!

Is neem oil a pesticide?

Yes. According to the World Health Organization, pesticides are “...chemical compounds that are used to kill pests…” However, neem oil has significantly fewer risks associated with it compared to nearly any other pesticide.

What should I do if I get neem oil on my skin? Is it dangerous?

The biggest symptom you may experience is irritated skin. The best thing to do if you get neem oil on your skin is to wash your hands promptly with soap and water. Unless you have an undiscovered allergy or sensitivity to neem oil, you should have no negative effects from it.

Is neem oil toxic to animals, pets, bees, or fish?

According to the National Pesticide Information Center, “Neem oil is practically non-toxic to birds, mammals, bees, and plants. Neem oil is slightly toxic to fish and other aquatic organisms.” If the oil is sprayed directly on a bee, it will harm it, but a bee has no negative effects from landing on or pollinating a plant treated with neem oil.

What plants should I NOT use neem oil on?

You may get a different answer to this question depending on who you ask. In short, if a plant is sensitive or delicate, you may want to avoid using neem oil. Some people say to avoid spraying it on herbs and leafy greens altogether; I say that as long as the plant is not newly transplanted or water-stressed, it should be fine. If you are worried about it, you can test a small part of the plant to see if it has any negative effects before coating the entire plant.

Does rain wash neem oil off?

If the neem oil is freshly applied right before it starts raining, yes, it may get washed off. If the oil has had about 24 hours to dry and/or be soaked into the plant, this isn’t an issue. However, I do generally recommend reapplying neem oil after rain has stopped and the leaves have had time to dry, especially if you are trying to control a mold or fungus like powdery mildew.

Can you eat plants that have been sprayed with neem oil?

Yes! Neem oil is considered safe for consumption when used properly. It is recommended to give the plants a rinse or wash before eating them, just like you would any produce.

What is the best time of day to apply neem oil?

Generally speaking, early in the morning or late in the evening is the best time to apply neem oil. Applying neem oil in the heat of the day in direct sunlight can increase the chances of leaf burn, but this depends on the weather. These times are also best because beneficial insects will likely be less active, decreasing the chances they will be sprayed accidentally.

When should I stop using neem oil?

Continue to use neem oil even if an infestation appears to be under control; simply decrease the frequency of spraying. You should only stop using neem oil if temperatures get extreme (hot or cold) or if the plants get transplanted or water-stressed.

Whether you're dealing with pesky aphids, fungal flare-ups, or just trying to keep your plants looking their best, neem oil offers a reliable, organic option that both new and experienced gardeners can feel good about. Remember, consistency and proper application are key! With neem oil in your gardening toolkit, you’re all set to give your plants the TLC they deserve, safely and naturally.

Lara Wadsworth, True Leaf Market Writer

I am a native of Southwestern Michigan, where I currently reside. I love all things plants! After completing a Bachelor's Degree in Horticulture, I found a dream work-from-home job that allows me to share my passion. Now, I spend my days writing for TLM, playing with my dog, eating delicious food with my husband, and plotting my next landscape or gardening move. I believe everyone should get down and dirty in the soil now and then. Happy Gardening!