Neem oil has long been touted as a very successful treatment method for common houseplant pest infestations. This natural substance is versatile, both in the number of different pests and diseases it treats and for its various methods of control. What exactly is Neem oil, and how does it work?
Neem oil is a naturally derived material made from the seeds of Neem trees. This oily substance acts as a pesticide in a variety of ways, including repelling insects, inhibiting growth and feeding, and smothering pests, causing death. When applied correctly, Neem oil does not impact plants, humans, or pets.
There are a lot of good reasons to incorporate the use of Neem oil into your pest-management practices. This natural, low-impact, safe product can be used in a variety of different ways and works on many different kinds of pests and fungal diseases.
In this article, we’ll do a deep dive into what exactly Neem oil is and how it works against pests on your houseplants. We will also cover a lot of commonly asked questions on how to buy, store, mix, and apply Neem oil.
What Is Neem Oil?
Neem oil is a product that is produced by pressing the seeds and fruits of the Neem tree (Azadirachta Indica), a variety that is native to South Asia, mainly in India and surrounding areas.
The oil produced from these pressings is usually brown or yellow and has a harsh, garlic-sulfur smell. It contains a multitude of naturally derived chemical compounds that mostly seem to act as natural pesticides, although some have antiseptic qualities that are effective against a myriad of fungal diseases, as well.
Neem oil has long been used as an effective option for pest management in organic farming and has been a long-standing treatment option for indoor pest infestations, mainly because of its ease of use and safety.
How Does Neem Oil Work?
Although several compounds within Neem oil are still not fully understood, it does contain a few that seem to have very strong pesticidal qualities. The most studied one, called Azadirachtin, is well known to discourage pests in various ways and has since been added to several branded commercial pesticides used in farming and horticulture.
Neem oil is also, well, an oil. When applied to the surfaces of a plant, Neem coats and sticks to any pests present, causing issues with feeding and respiration.
Additionally, its smell tends to be very offensive to many different pests, making it a great repellent, as well. Although not primarily used in this way, you can probably understand the benefits of repelling additional pests while treating for current infestations.
Why Does Neem Oil Kill Bugs?
Because of its many different chemical components and oily texture, Neem oil works to kill bugs in a couple of different ways. First and foremost, as an oil, Neem tends to cover everything it is sprayed upon. Any pests that get coated with it become trapped in the viscous liquid. It covers their bodies completely and begins to gum up their mouthparts and respiratory systems, causing them to suffocate and die.
As if that wasn’t enough, that main active compound in Neem oil, Azadirachtin, works as both an antifeedant, meaning that it suppresses appetites and feeding, and as a growth regulator, inhibiting hormones that lead to molting and egg production. It effectively controls the number of individuals that can become adults capable of reproducing.
Many houseplant pests have lifecycles of just a couple of weeks, so you can imagine that a few applications of Neem oil can have a devastating effect on a population’s ability to thrive.
Neem oil has been known to effectively treat for household pests like aphids, thrips, spider mites, mealybugs, scale, and whiteflies, as well as many other pests found out in the yard.
Can Neem Oil Be Used Indoors?
Neem oil was originally produced as a biopesticide used in ventures like organic farming and horticulture; however, its effectiveness on indoor ornamentals was quickly realized and capitalized on.
Because it is naturally derived from plants and is a low-impact product that tends to dissipate in the environment rather quickly, it is actually a great product to use for pest management in your home.
Most Neem products are sold as ready-to-spray formulas, meaning they’ve already been diluted to effective but safe strengths. Even if you mix your own solution from concentrated Neem oil, your risk of any negative effects is very low.
How Should Neem Oil Be Purchased and Stored?
While Neem oil is, generally, a pretty straightforward product to buy, store, and use, there are several different formulations on the market with only slight variations, tripping some people up and causing confusion on what they should be looking for.
Additionally, there are different methods of processing Neem oil, some of which result in less-potent formulations. Let’s go through a few questions about what to look for when buying Neem oil.
What Is the Best Neem Oil for Plants?
There are several different formulations, from concentrates to ready-to-use sprays, and many commercial brands often add Neem oil, or at least its active ingredient, into their products to make them more effective. It can be hard to cut through the noise, but you will often have the most success with Neem products that are the purest and least processed.
Cold pressed Neem oil is a great start! This method of processing is very minimal, and you end up with a product where all the biochemical compounds are retained, making it a more effective formula. Buying pure Neem oil concentrate to mix yourself will offer you the best control.
Unfortunately, most ready-to-use spray formulations use Neem oil extracts or derivatives rather than the pure stuff. They still work, to some degree, but because they are often more processed, not as much of the active ingredient is left, which lowers their potencies.
What Is Cold Pressed Neem Oil?
Quality Neem oil all starts with how it is processed. Just like with any naturally derived product, there are often different ways to get it out of nature and into our hands. How that happens has an impact on both the quality of the product as well as its price.
Cold pressed Neem oil is made by running the seeds and fruit of Neem trees through machinery that uses pressing and crushing movements to extract the oils from the plant parts without external heat. This creates a higher quality product that retains its collection of biochemical compounds.
The addition of heat to the process might help separate more oil from the organic matter, but it also destroys a lot of the compounds that contain the insecticidal qualities we want Neem oil to have. This means that cold pressing sacrifices yields, but you end up with a much higher-quality product in the end.
In fact, many Neem products that are not cold pressed are often sold as “extracts”, meaning they did technically come from Neem trees, but they aren’t the same products as cold pressed oil. These extracts are often much cheaper, but they don’t have the same efficacy as pure Neem oil, and these inferior products will often disappoint customers when they don’t work as advertised.
Is Neem Oil Organic?
Typically, if you are buying a high-quality, cold pressed Neem oil product, you are buying a substance that has been extracted from a tree, without the use of chemical processing, and therefore, should be organic. And, as expected, most Neem oil products are organic.
However, you should be aware that certain products containing Neem oil might have other ingredients that are not organic. You should always pay close attention to any labels on the formula you are considering for purchase to see if they have any additives or chemicals that make the product more dangerous or harmful.
In many cases, quality Neem oil producers will include a sticker on their label showing the product is “100% Organic”.
Should I Buy a Concentrate or a Ready-To-Spray Product?
If you like the idea of having Neem oil on hand for use against fledgling pest issues on your houseplants, you have a few different options.
Ready-to-spray formulations are super handy, mainly because you don’t have to do any measuring and can basically just point and shoot at your intended targets. They also take up less space and are usually already in a spray bottle. However, finding premixed products with pure neem oil is hard to do, so you often sacrifice efficacy for efficiency.
Instead, these products will often contain hydrophobic extracts of neem oil, which is the result of harsher processing practices. Some of these products still do a pretty good job for minor infestations, but if you want to utilize the power of pure Neem oil, you’re better off buying a concentrate.
Pure Neem oil is essentially a 100% concentrate, which you mix with water to dilute its strength to a level that is safe to use on plants. There are other various concentrates on the market that mix pure Neem oil with varying amounts of emulsifiers, which are substances that help keep the oil in solution when mixed with water.
If you want to use pure Neem oil as a spray, you will also need to add an emulsifying agent into the solution because oil and water famously do not mix well. At home, a small amount of a natural dish soap does the trick.
Aside from having to mix up batches for use, pure Neem oil and its various concentrations are often more expensive than ready-to-spray formulations. While not outrageously priced, you may experience a little sticker shock, but just know that you are getting much more bang for your buck.
Mixing your own formulations from pure Neem oil typically results in a much more effective product, so you end up using less during applications. This means even a small bottle goes a long way.
Are Neem Oil and Horticultural/White Oil the Same?
Although sometimes mistaken for one another, Neem oil and horticultural oil are not the same thing. Yes, they do look similar, and they do have similar modes of action against pests, but that’s about all they have in common.
Remember that Neem oil is derived from tree seeds and contains a multitude of naturally produced chemical compounds that have insecticide-like qualities. Neem oil works to not only suffocate bugs on contact but also inhibits growth and feeding with these chemical compounds.
It is very low-impact and biodegradable, with a lower risk of harming beneficial insects like bees and ladybugs.
Horticultural and white oils are usually derived from various sources, including petroleum, vegetable oils, or mineral oils. They lack any naturally derived chemical insecticides and only work by coating and suffocating bugs on contact. Sometimes, they can contain additives or synthetic chemicals to help increase their efficacy.
Depending on the type of oil used, horticultural oils can have more of an impact on the environment, especially if they are petroleum-based.
Can Neem Oil Go Bad?
Pure Neem oil is a fully natural product, so it makes sense to wonder about whether or not it can spoil or go bad. When mixed and applied to plants, it actually only has a few days before the chemical compounds of the oil biodegrade and dissipate.
However, when stored properly, Neem oil has a pretty long shelf life. Even opened oil can stay fresh for one to two years, sometimes longer, if kept in the original packaging with the lid screwed on tight.
Its potency may begin to slowly decline after opening, so keep that in mind when purchasing. There’s no sense in keeping a huge bottle of it on hand if you aren’t going to use it. Typically, after about two years, you might notice some discoloration or cloudiness in the oil, which means that it has started to turn bad or rancid.
Many products will have a “best by” date stamped onto the container, which is a pretty good guideline for when it might start losing some potency. Some go even further and add an “expiration date,” which is when it will likely have gone bad.
Should Neem Oil Be Chunky?
Have you ever placed a bottle of olive oil in the refrigerator and seen it solidify? Or maybe you’ve noticed your jar of coconut oil turns to liquid on a really warm day? This is because of their melting point, and Neem oil has one, as well.
Neem oil is a liquid at normal room temperature but will begin to solidify as temperatures drop and start approaching its melting point, which is around 55°F. If you notice your oil is chunky, it’s likely just because you have it stored somewhere a bit cooler, like a garage or shed.
It’s nothing to worry about. Just set your container of Neem oil in a warm water bath for a few minutes to liquify any chunks before measuring out what you need.
Should Neem Oil Be Refrigerated?
A little bit of pure Neem oil can go a very long way, meaning an 8-ounce bottle might last a causal houseplant enthusiast several years. If you’d like to help preserve your Neem oil and maintain its potency, storing it in a cool, dark place is a good start. However, popping it in the fridge just might keep it fresh even longer.
Neem oil stored in a refrigerator at around 34-40°F might last several months to a year longer than if it was stored at room temperature.
If you do decide to store your Neem oil in the fridge, just know that it will be solidified, so remember to pull it out to melt at room temperature or give it a warm water bath before you need to use it.
How Should Neem Oil Be Used?
Once you’ve decided what type of Neem oil you want to work with, you need to be comfortable with mixing and applying it to your plants. This will depend greatly on what type of Neem oil product you purchased.
Let’s assume that if you went for a ready-to-spray product with a Neem oil extract in it that you will apply it according to label instructions. Most of these products truly are point and shoot, so it takes a lot of guesswork out of the application process.
Concentrates and pure Neem oil are a different story.
How Do I Mix Neem Oil for Plants? Should Neem Oil Be Diluted?
Neem oil concentrates can be pretty strong, so they almost always should be mixed with water before applying through a sprayer or watering can. Concentrates that have certain percentages of emulsifiers mixed into them will usually have instructions for mixing on their labels, which you should follow for best results.
Pure Neem oil has no added chemicals, emulsifiers, or water to it, so you will need to create a mixture that is right for your houseplants. Applying a mixture that is too strong can end up burning plant leaves or causing damage to tender, young plants.
A good starting point when using pure Neem oil is to aim for a mixture that is about one ounce of oil to one gallon of water. Many of us don’t need nearly that much at one time, so cutting down that recipe works out to about 1½ teaspoons of Neem oil to a quart (32 ounces) of water.
As mentioned above, oil and water don’t mix well without some kind of emulsifier, so the addition of about ½ teaspoon of dish soap to that quart mixture works well. This is just enough soap to keep the solution from separating.
Aim to use a neutral or natural dish soap to avoid spraying any harsh chemicals onto your plants. Castile soap is a great option. Many laundry detergents and specialty “grease-fighting” soaps can be too strong, even at those low amounts.
You can tweak the amounts above to make stronger or weaker solutions, depending on your needs. Keep an eye on dainty or frilly plants. If they don’t fare well after an application, you can mix up a weaker batch the next time you need to spray.
When Should Neem Oil Be Applied?
In general, you can apply Neem oil any time you notice one of your houseplants harboring a pest infestation. The earlier you apply it, the better chance you have at knocking down a bug population and minimizing the number of repeat treatments needed.
If you are applying Neem oil to an outdoor plant or a houseplant you’ve quarantined outside, aim to treat earlier in the morning, before pollinators are out and about. In general, Neem oil is quite safe for beneficial insects, but it’s still best to avoid spraying them directly.
Where Should Neem Oil Be Sprayed?
Neem oil is a contact-based pesticide, meaning that it has to actually coat a bug in order to kill it. If you don’t get good coverage when spraying it, you won’t have a lot of success in controlling the infestation.
Spray where the bugs reside. In most cases, houseplant pests really like the undersides of leaves, stem divisions, and tender growth. Concentrate on coating all surfaces of the plant, paying special attention to these specific areas. Dense foliage can be a good hiding spot for pests, as well, so pruning back thick foliage, or at least spreading it out while you spray will help.
Can Neem Oil be Applied to Soil?
One really cool feature of Neem oil that often goes overlooked is that you can apply it to your plant’s potting soil to help control soil-dwelling bugs and fungal infections.
By applying Neem oil as a drench, you can target any pest that lives even part of their lifecycle in the soil (take that, fungus gnats!). The added benefit is that Neem oil’s antifungal properties can also clear up any potential fungal infections that commonly affect houseplants.
Again, a good starting point for a drench is 1½ teaspoons Neem oil, ½ teaspoon dish soap, and a quart of water.
How Often Should Neem Oil Be Applied?
In general, a Neem oil mixture at about one ounce per gallon of water is safe to apply to plants once every seven days. This ensures the treatment has time to work and the plant stays safe and healthy. Because pure, cold pressed Neem oil is more potent than many of its derivatives, you’ll probably find that fewer applications are necessary to gain control of a pest issue.
That being said, if you are dealing with a particularly nasty infestation, you may find that a repeat treatment five days later is a necessary interval to gain the upper hand. Some pests, like aphids, have ongoing lifecycles that are fast and hard to disrupt, so waiting a week between treatments can give any surviving adults time to produce additional offspring.
Should Neem Oil Ever Be Washed Off of Plants?
Neem oil is considered to be a safe treatment for most plants, but sometimes, it can leave behind a residue or film once the mixture has dried. This makes some folks wary, but it usually isn’t an issue and, in fact, often helps by repelling new pests from visiting the plant.
If the residue left behind from a Neem oil treatment bothers you, feel free to wash it off or wipe your plant’s leaves with a damp cloth.
If you ever notice that your plant is suffering after an application of Neem oil, in particular, you see leaves burning, you should immediately wash your plant and try to remove as much Neem oil as possible.
Burned leaves can happen if the Neem oil mixture is too strong or if the plant receives too much sunlight immediately after an application. Either way, you’ll want to remove as much of the oil as you can and let your plant recover before reapplying.
Are There Risks Associated with Neem Oil?
Aside from just a few minor risk factors, Neem oil is very safe to use on your houseplants. Leaf burn can happen, but only when the oil is applied incorrectly or on the wrong plants. Beneficial insects are usually unaffected unless directly hit during application.
Final Thoughts
As you can see, Neem oil is a fantastic, natural pest control that is versatile, safe, and easy to use. It works on a variety of houseplant pests, and its efficacy and effectiveness far outweigh any of the minor risks associated with it.
Feel free to try some of the ready-to-spray formulas, but if you’re willing to make your own mixture, the added strength and benefits of cold pressed pure Neem oil will provide better control of pests in the long run.
Now that you know how to mix and apply Neem oil, no pest is safe in your home!