Will Neem Oil Hurt My Plants?

I prefer to use natural insecticides wherever feasible as an organic gardener, especially when it comes to my vegetable plants. I’ve read a lot about neem oil’s effectiveness in battling fungus and insect infestations. However, I have also seen conflicting accounts concerning its safety. I made the decision to research it and learn the truth as a result.

Neem oil applied to plants is it safe? Neem oil is safe, yes. India has been using neem oil as a pesticide on plants for more than 400 years. Neem oil application doesn’t hurt the crops, the people who consume them, or the environment. Neem oil should not be sprayed directly onto the skin since some people may experience an allergic or respiratory reaction.

It turns out that neem oil is a fantastic tool in the ongoing battle against garden pests. It is a useful tool to have in the arsenal even though it cannot resolve all issues. Neem is the only plant that has the natural pesticide used in neem oil. As an insecticide, it is non-toxic. It matters what kind of neem is used, as well as how it is applied. Before using neem oil to treat insect infestations in gardens, it’s necessary to understand the following.

If neem oil is sprayed on the plants, such as lettuce and kale, can I harvest and eat those greens right away, or do I have to wait a certain length of time?

It is acceptable as long as the greens are fully cleansed. It makes no sense to apply the oil to the kale before harvesting, though. Kale should be harvested before spraying. On plant leaves, neem oil degrades in 2 to 5 days. The best scenario is to spray well in advance of when you plan to harvest.

Is neem oil safe for humans, dogs, and cats?

Neem oil is deemed generally safe for humans by the FDA. Toothpaste, shampoos, and soaps all include extracts from neem oil. However, the items don’t include neem in its whole and aren’t exactly the same as what is found in insecticides.

Neem can be hazardous if not used correctly. Neem oil applied correctly to plants and vegetables won’t produce dangerous quantities. All treated veggies should, however, be washed before consumption. The oil can be eliminated with a vigorous water wash.

Skin irritation or an allergic reaction may be brought on by neem oil. When working with neem, for instance, caution is always suggested, as is wearing protective clothes.

Neem is not listed as hazardous to dogs or cats by the ASPCA. Animals living in water are only mildly poisoned by neem oil.

Which pests does neem oil kill?

Only soft-bodied insects, larvae, and eggs are effective with neem oil. Although it can kill their larvae, it does not harm insects with hard bodies, such as beetles. In addition, it functions as a fungicide for white powdery mildew.

Aphids, mealybugs, caterpillars, spider mites, lace bugs, thrips, whiteflies, cabbage loopers, leafhoppers, leafminers, and beetle larvae are a few of the pests that neem oil is effective against.

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How does neem oil work?

Neem oil has two purposes. The oil splashed onto the plant coats its leaves. The oil enters the insect’s respiratory system as it consumes the leaf, suffocating it.

Azadirachtin, a natural pesticide, interferes with insect systems. They are unable to breed, feed, or fly since it prevents all of their hormonal actions. Eventually, they will go extinct.

Neem oil takes time to start working. The insects entirely pass away after around 72 hours. Sometimes results are seen in less than a day, but the entire impact takes longer.

Does neem oil harm beneficial insects?

Because they are not consuming the sprayed leaves, beneficial insects like bees, butterflies, and ladybugs are not harmed by the insecticide. They might touch the leaves, but that won’t do any harm. If they are on the leaves, butterfly or ladybug eggs and larvae may be harmed. Use it sparingly and only on plants that are plagued with pest insects; avoid applying it widely.

Neem oil kills all insects when applied because it blocks their airways and causes them to suffocate. Neem oil treatments should be made in the morning before butterflies and bees emerge in order to protect beneficial insects. Additionally, to reduce any negative effects, only spray the harmed plants.

Which neem oil product is best?

There are numerous ready-spray neem-based insecticides available at the garden center. The majority of these include neem oil’s hydrophobic extract. This extract is neem oil fragments mixed with an alcohol or chemical. The organic pesticide azadirachtin is absent. Avoid using these products. They accomplish nothing beyond what vegetable oil accomplishes.

100% cold-pressed neem oil is the best neem pesticide product. This has azadirachtin as well as all the other qualities of neem seeds. Prior to usage, it must be mixed, however mixing it is easy.

Here is a link to the Amazon page where I purchased the 100% cold-pressed neem oil that I used in the images up there.

Which plants should not be exposed to neem oil?

I started using neem oil in my garden a few years ago to get rid of spider mites and aphids, and I’ve grown to adore it. I’ve had great success using neem oil, which naturally repels insects, especially when it comes to keeping the pests away from my tomato plants.

But I recently discovered a hard lesson: Neem oil simply isn’t a favorite among all plants. Thus, the issue arises: Which plants should you avoid using neem oil on?

Herbs like basil, caraway, cilantro, dill, marjoram, oregano, parsley, or thyme shouldn’t be sprayed with neem oil. Neem oil should only be sprayed sparingly on plants with fragile or wispy leaves, such as spinach, arugula, lettuce, and peas, to avoid burning the foliage.

Be careful while mixing and applying neem oil, though, as even hardier plants with tougher foliage might be scorched (or even killed) if you don’t.

Neem oil is made to cover a plant’s leaves and any invasive insects lurking among them in an oily film that will suffocate some insects and harm many others by damaging their cells. Neem oil is an oil, though, so even on a moderate day, if you ignore good advise and spray at the wrong times, you risk literally cooking the leaves of your plants.

In light of this, let’s look at a list of plants that tolerate neem oil, those that are sensitive to neem oil, and those that don’t actually require neem oil because they already ward off many of the most pesky bugs.

Can neem oil be applied to any plant?

Neem oil is therefore a very efficient means of eliminating pests, but can it be applied to any plant? Neem oil can be applied to the majority of plants, but it won’t work on plants with rough surfaces. Neem Oil won’t work on your plants if they have fur, needles, or any other features that might make it easier for pests to hide deeper inside the leaves. Neem oil should not be used to plants with fuzzy leaves, such as the majority of Calatheas.

What occurs if neem oil is applied to plants excessively?

Numerous organic chemical components have been found in neem oil, as demonstrated by studies, however azadirachtin is by far its most significant component.

This naturally occurring substance doesn’t kill pests right away, but after ingesting it, it will interfere with their capacity to feed, molt, and breed, ultimately killing them within a week.

Bugs are also covered in a thin coating of oil by neem oil. If you spray adult, hard-bodied bugs with neem oil, such as leaf-footed bugs, squash bugs, and stink bugs, they will get irritated but usually not die. Aphids and spider mites, which have smaller, softer bodies, are more vulnerable to anything that covers them in oil, especially if they are in the nymph stage. The azadirachtin will kill them if the oil itself doesn’t.

Fortunately, the oil won’t harm helpful pollinators, and once it’s diluted, sprayed on plants, and exposed to sunlight and the environment, it will start breaking down swiftly.

Neem oil can be applied more than once every 4–7 days, although generally speaking, you shouldn’t do so to maximize its effectiveness.

In other words, if you apply neem oil every 1, 2, or 3 days, you’re using it excessively and risk causing your plants slow-moving, long-lasting harm.

Neem oil will cover the leaves, branches, and blossoms of your plants in a thin film of oil, which is why it is true.

As I mentioned above, this oily layer will begin to disappear within a few hours, but if you keep reapplying neem oil without timing your applications properly or separating them so that the oil completely degrades in between, you risk seriously harming your plant in two ways.

Foliage Burns

The most obvious approach to harm your plants with neem oil is in this manner. Neem oil will heat up if it is exposed to direct sunshine before it has had a chance to properly dry, just like the oil in your frying pan does when it is exposed to higher temperatures.

Neem oil will likely harm whatever leaves it comes in contact with once it has heated up, resulting in burns that appear as streaks, splotches, or even spots, as well as eventual leaf rot. If your plant has too much neem oil on it, you risk completely killing it by damaging too much of its foliage.

Neem oil spray applications should always be made in the early evening for the simplest way to prevent these issues. While the light is still bright enough for me to see clearly, I do this as it is setting. As a result, there is no doubt that the neem oil will have at least 10 hours to dry before the sun rises the next day.

I once neglected to apply neem oil in the evening and, against better judgment, chose to do so the following morning. I believed that by doing it early, it would dry before the sun could do any harm, preventing any scorching.

Fortunately, I had only lightly sprayed a few plants with neem oil, so they quickly recovered. However, I learned from the experience not to try to make up for missed neem oil applications the following morning. Simply wait until the suitable time the following day, then spray your plants.

Neem oil treatments frequently can result in unwanted side effects on three critical biological processes that all plants carry out in addition to the potential for foliage burns:


The process through which plants convert carbon dioxide, sunshine, and water into oxygen and carbohydrates is known as photosynthesis. However, the precise mechanism by which this happens is less well understood.

Simply put, stomata (or stoma if you’re referring to a single pore) are epidermal pores found in plants. By absorbing carbon dioxide from the environment, these tiny apertures are crucial to photosynthesis. The cells that surround each stoma serve as gatekeepers. When there is sufficient carbon dioxide in the plant, the cells close the stoma to momentarily slow or stop the flow; when there is insufficient carbon dioxide in the plant, the cells open the stoma to let more CO2 in.

Therefore, stomata are essential for photosynthesis. They don’t participate in the actual chemical reactions occurring inside the plant, but they do manage how much and how frequently carbon dioxide enters the plant, so regulating a crucial aspect of photosynthesis.


To take in carbon dioxide, stomata open, but in the process of doing so, they also lose something: water. Also in plenty. According to the U.S. Geological Survey, a single huge oak tree can transpire up to 40,000 gallons of water annually, compared to up to 4,000 gallons for an acre of maize.

The stomata control when and how much each plant transpires at any one time. Transpiration fluctuates depending on a wide range of conditions, including heat, humidity, wind speeds, and soil moisture, to mention a few.

Oxygen Release

When plants engage in photosynthesis, they draw carbon dioxide from the atmosphere and combine it with water to produce oxygen and carbohydrates using energy from sunshine. As an unneeded consequence of the photosynthetic process, they then expel the extra oxygen.

It should come as no surprise that these exchanges also happen through the plant’s stomatal openings, especially during the day. As a result, the open stomata serve two purposes: they let CO2 in while also enabling oxygen to escape.

Studies have demonstrated that anything that interferes with these stomatal routes would have a negative effect on plants, obstructing their biological functions and retarding their growth.

And this brings me to my concern with neem oil: if you spray neem oil too much and too often, you run the risk of coating and re-coating your plant’s leaves in oil, which could clog the stomata and impair the plant’s capacity to absorb carbon dioxide and release both water and oxygen.

Neem oil: does it damage plant roots?

Bees, butterflies, earthworms, and ladybugs—insects that benefit your plants—aren’t harmed by it. It doesn’t impact insects that dwell on the plants; rather, it targets insects that try to consume the leaves, stems, and roots of the plants.

When should neem oil not be used?

Neem must be mixed and applied correctly in order to be effective; otherwise, it could harm plants, beneficial insects, or aquatic life.

Where NOT to use Neem OIl

Neem oil is safe for many species, however when applied topically to plants as a foliar spray, it doesn’t distinguish between good and bad insects.

Health hazards may also result from its capacity to interfere with hormones in some situations.

Here is a critical list of situations in which you should not use specific neem products:

  • NEVER apply foliar sprays during the day because it can come into touch with bees and other helpful insects and pollinators. Check out Neem Oil and Bees.
  • Never use neem foliar sprays in close proximity to beehives as the wind could blow droplets to the nest.
  • NEVER use neem products in close proximity to any body of water that has aquatic life. Neem products are prohibited in Canada and the UK because it is somewhat harmful to many fish and amphibian species.
  • AVOID using while there are kids or pets present because they might consume more neem than is safe.
  • Neem has been known to cause seizures or other ill effects when consumed by young children, though these risks decrease as the child gets older. NEVER leave neem items around little children.
  • If you are pregnant or nursing, AVOID getting into close touch with neem products since it can lead to problems or even miscarriage and may also contaminate your breastmilk.

Testing Plant Tolerance

In the meanwhile, plants that ought to be neem-tolerant may experience sensitivity or an allergic reaction, just as people occasionally do to peanuts or other typically harmless goods.

Apply a very small amount to a single, isolated area of your plant to test it.

Apply foliar sprays to a single leaf, and use an eyedropper to give a few drops of soil soak to the stem of a plant close to the base.

A plant should not be treated with neem treatments if it exhibits symptoms of sensitivity.

While some manuals advise testing before each usage, others view it as a one-time thing.

Since plants might change their sensitivity over time, we advise using your own judgment when deciding how frequently to test, but you should aim to do so at least once each year.

When to Apply Neem Oil

Neem oil, as previously indicated, can harm both good and evil insects if used improperly.

Always apply any necessary medicines at dawn or dark to protect bees, ladybugs, and other garden creatures.

Neem foliar sprays evaporate within 45 to 1 hour, so they won’t be present when these assistants begin their daily (or nighttime) routine.

Avoiding sunburn on indoor or outdoor plants is another justification for applying at these periods.

Applying neem oil when the sun is up increases the chance that the sunlight may scorch the leaves since neem oil is mixed with warm water.

Neem is often non-toxic, but you shouldn’t eat any when you’re eating fresh vegetables.

In order to avoid mistakenly overwatering a plant, it is also recommended to administer soil soaks when the plant is thirsty.

Applying Foliar Sprays

Foliar sprays need to be administered more regularly and require more effort than soil soaks.

Spray the entire plant, being care to reach any crevasses and the undersides of all the leaves.

You will need to reapply every other day for 14 days during bug outbreaks.