Is It Worth Using Neem Oil to Control Pests in Cannabis Plants?

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Added 24 November 2022

In the past, farmers didn’t have the luxury of purchasing the most potent pesticide to eliminate pests on their farms. They primarily relied on various natural products readily available around them to fight off pests.

Over the centuries, through trial and elimination, farmers narrowed down to a few natural compounds that are effective at eliminating pests. One such compound is neem oil. Tried and tested by farmers and gardeners around the world, neem oil is one of the best natural pesticides to deter pests on cannabis plants. 

So, what is neem oil, and is it effective to deter pests on cannabis? Here’s everything you need to know about neem oil, including how to make it at home and how to use it the right way. 

What is Neem Oil and How is It Made?

What is Neem Oil and How is It Made?

If you are an active gardener, you probably already know how beneficial neem oil is for pest control. It is one of the most effective and organic ways of eliminating and controlling pests in plants. And this organic pesticide has been in use for centuries. 

As a cannabis grower, you face a constant threat of pests attacking and damaging your plant, and this is where neem oil comes in handy. It is useful for various plants, and cannabis is no different. 

Essentially, neem oil makes living and reproducing difficult for pests on your plants — it affects their ability to feed and lay eggs, which forces the pests to look for another home. More on this later.

Neem oil is made from neem, or the Azadirachta indica tree, which is commonly found in South Asian countries, especially India. The tree is even introduced to various other tropical and subtropical regions because of its importance in farming and medicine. 

The neem tree grows small white along with small yellowish or green fruits (that sort of look like olives), and these fruits are the major ingredient for producing neem oil.

Manufacturers produce neem oil by grinding and pressing the seeds and fruits, which produce the purest form of oil. Some manufacturers even extract the oil using solvents, although the quality is not on par with grinding and pressing. 

Fun fact: Apart from being beneficial for gardening, neem oil is also quite good for your health. It can help treat bacterial and fungal diseases, including various skin infections. However, the dosage and effects may vary, so it’s recommended you use it only if your physician advises it. 

How Effective is Neem Oil Against Pests?

How Effective is Neem Oil Against Pests?

Short answer: very effective. Long answer: neem oil works in two ways to deter and eliminate pests on cannabis plants — it affects the insect’s ability to feed and reproduce. 

According to the National Pesticide Information Center, neem oil contains many compounds, with the most active one being Azadirachtin, which is responsible for reducing insect feeding. This compound interferes with the hormone systems, which also makes it harder for pests to grow and lay eggs. 

And according to the University of Connecticut, the same compound, Azadirachtin, also disrupts the mating and sexual communication of the insects, which further reduces their chances of reproducing. 

Some experts also believe that neem oil coats insects, reducing their breathing abilities, which can be fatal for them. However, this is not always the case and not a lot is known about this aspect of neem oil.

Yes, while neem oil won’t necessarily kill pests on contact unlike many synthetic pesticides, it will deter pests and stop them from growing in numbers. If you use neem oil the correct way on your cannabis plant, the pests will be forced to move out of your garden and look for a new home as your plant will no longer be a safe environment for them to live in.

In fact, neem oil is effective against over 200 species of pests, including the common cannabis pests like aphids, whiteflies, spider mites, thrips, broad mites, fungus gnats, and mealy bugs.

It is most effective when it is used as a foliar spray on both outdoor and indoor hydroponic cannabis plants, but if you are facing a pest problem under the soil, it can even be used as a soil drench. 

Neem Oil’s Effect on Beneficial Bugs

Not all bugs are bad for cannabis, some are good. They can work in synergy to create an environment that benefits the entire garden ecosystem. But wouldn’t spraying neem oil also kill the beneficial bugs?

Not really. Perhaps the best thing about neem oil that sets it apart from other pesticides is that it does not affect most beneficial bugs like butterflies, ladybeetles, praying mantis, bees, rove beetles, and earthworms. So, you don’t have to worry about deterring them from your garden when using neem oil. The same can’t be said for many synthetic pesticides, right?

Neem Oil Against Fungi and Mold on Cannabis

What’s more, neem oil can also help you treat fungal or mold problems, including root rot, on your cannabis plant. It can do so by making the growth of mold and fungi a lot more difficult as it hinders their ability to reproduce.

How to Make Neem Oil for Cannabis at Home?

While you can buy neem oil from your local gardening store, it is still recommended to make neem oil at home. This is due to a couple of reasons. Premade neem oil products are generally well-tested, but they may not contain adequate Azadirachtin required to eliminate pests on your cannabis.

On the other hand, you can be sure the neem oil made at home, as long as you use the correct preparation method, will have the right amounts of Azadirachtin. Plus, homemade neem oil wouldn't contain any additional compounds that are not required — something which you can’t always avoid with store-bought neem oil products.

However, caution is recommended for making neem oil at home if you plan to use it on any plant other than cannabis. It is generally safe for most plants, but some plants tend to react negatively to neem oil.

Follow these steps to prepare neem oil for cannabis at home.

Step 1. Get the Right Base

Get the right base

The first thing you need to do is get the base — high-quality neem oil extract that is 100% raw or crude. Plus, ensure the base is cold-pressed; heat-pressed oils do not contain azadirachtin. You can even get organic neem oil as it is not contaminated during the purification process.

One can never be sure of cold-pressed neem oil in terms of its efficacy because the packaging does not always contain how strong it is against pests. So, if you want to be more clear about how strong your neem oil is, you can even use neem oil insecticides that specify the exact percentage of azadirachtin present within. 

Step 2. Emulsify the Base

Emulsify the base

Oil and water don’t mix well, so, you need to emulsify the base neem oil so it can be mixed well with water. Otherwise, your neem oil solution would be unevenly mixed and can affect some areas of the plant that receives a higher concentration.

You can use organic soap or silica as emulsifying agents.

If you want to get even more benefits, you can choose potassium-based insecticidal soaps, too. Just ensure it is free of any toxic or harmful ingredients that can affect your plant. Potassium soap is another natural insecticide that can kill pests on contact, but it’s slower than neem oil to act, but when you mix the two, you get the best of both worlds!

Plus, when potassium soap disintegrates, it turns into potash, which is a natural fertilizer. Win-win situation. 

Step 3. Mix It with Water

Mix emulsified base with water

The next step is to mix the base and emulsifier with water to create your homemade neem oil pesticide. 

In this recipe, we are preparing a gallon of neem oil spray, but you can change the quantities as per your preferences. However, ensure the ratio between the base, emulsifier, and water remains the same. 

First, add a gallon of warm water to a container and mix 1 teaspoon of liquid soap with it. Next, add 4 teaspoons of neem oil to the mix. You must add the soap to the water before adding neem oil.

On the other hand, if you are using silica powder to emulsify neem oil, you can pre-mix some powder with water beforehand. Generally, 35 grams of silica powder should include 8 ounces of water. 

Finally, stir the mixture well. Once you have stirred it for a couple of minutes, you need to vigorously shake it to ensure an even mixture, and it's done. Use it within eight hours because the ingredients start breaking down over time. 

If you want to store the solution for longer, don’t mix neem oil into the water just yet. Mix them just before application.

How to Use Neem Oil on Cannabis to Deter Pests?

How to Use Neem Oil on Cannabis to Deter Pests?

You have prepared your neem oil, but what is the best way to apply it to your cannabis plant? You can either use neem oil as a foliar spray or as a soil drench, but ideally, it is recommended to be used as a foliar spray unless the pest problem exists under the soil. 

Just remember that when you are using neem oil as a drench, it will last up to 20 days in the substrate, but when used as a foliar spray, it will only last for 45 minutes before evaporating off. 

Here are some tips on using neem oil on cannabis plants.

1. Do a Patch Test First

No matter how careful you are, you can never be too sure how your plant will react to neem oil. Neem oil is safe, but due to environmental reasons or genetics, your specific cannabis plant may not be able to handle neem oil so well.

So, it is recommended that you do a patch test first on a small part of the plant, perhaps on an old leaf, and wait for a day before using it on the entire plant. If you notice any spots, discoloration, or other signs of stress on the leaf, neem oil may not be suitable for your cannabis plant.

2. Find a Good Spray Bottle

Many growers tend to buy any spray bottle they get their hands on — even the ones used in salons! But, you should not do that. Instead, choose a gardening spray bottle as they are specifically designed to use in gardens. They are more convenient and tend to be of higher quality than other regular spray bottles.

3. Spray Neem Oil Properly

When using neem oil, you don’t have to drench the plant (and its buds) in neem oil as it's unnecessary and can even harm the buds. Instead, you need a more focused approach. You need to spray neem oil where the bugs are, especially under the leaves, which is where most bugs like to spend their days. 

Also, ensure when spraying your plant gets full coverage but is not soaked in neem oil. Spraying too much neem oil can cause various problems for the plant, including light burns. Instead, the plant should be lightly damp after a neem oil application.

When using neem oil indoors, it is recommended to switch off the fans during application and only apply neem oil during the dark hours of the day. You can even turn the lights off for an hour. It is recommended that you avoid exposing your plant to light and strong wind when you are applying neem oil as it can cause light burns and other problems for the plant. 

4. Use Neem Oil to Prevent Pests on Cannabis

If you are using neem oil to prevent pests from attacking your cannabis garden, it is recommended to use neem oil throughout the plant’s vegetative stage, three weeks before the harvest time. Here, it works best as a foliar spray, which you can spray on your cannabis plants once a week. 

5. Avoid Spraying It On the Buds and Seedlings

In any case, never spray neem oil on the buds. Many experienced growers even suggest against using neem oil during the flowering stage because the tasty can be nasty when you prepare to smoke the buds. 

Sure, you can wash the buds, stems, and leaves before harvesting but neem is bitter and you will not appreciate the smell. Neem is strong and has a pungent aroma, which can stick to the buds and give you a minty yet pungent aftertaste when you smoke them. 

For example, neem oil is used to prevent children from sucking their thumbs as the strong taste is a major put-off for kids. Similarly, you will hate the taste of your buds if they contain even thin layers of neem. 

If you still have to use a pesticide during the flowering stage, you can look for an alternative to neem oil like baking soda or alcohol with water.

At the same time, you should not use neem oil on small seedlings as they cannot handle neem oil so well. While neem oil is completely safe for grown plants, it is still too harsh for seedlings. Once the plant turns a month old, you can use neem oil but start with a milder solution.

6. Spray During the Night 

If you are using neem oil as a foliar spray, only use it during the dark hours as it is more effective during this time (and it avoids light burns on the plant). During the dark hours, the beneficial insects are not so active and present on the plant, so you will avoid spraying on them accidentally. 

Plus, when you spray it at night, the solution stays for a little longer on the plant before drying out, making it more effective.

When Should You Not Use Neem Oil on Cannabis?

When Should You Not Use Neem Oil on Cannabis?

Apart from not using neem oil on young seedlings and flowering cannabis, there are other instances where it is not recommended to use on your cannabis plant, such as the following:

  • Avoid using neem oil on plants that have recently suffered from nutrient deficiency, overfeeding, or watering stress until the plant has recovered completely. 
  • Avoid spraying the solution on cannabis if the temperatures are too hot or cold or when the lights are on — this can cause light or heat burns on the plant. Instead, the best time to spray neem oil on cannabis is after sunset with temperatures ranging around 20°C or 68°F.
  • Stop using neem oil on your cannabis plant at least three weeks before harvest to ensure it does not alter the buds’ natural flavor profile.

If your plant is suffering from a pest infestation during these instances and you want a quick solution, you can choose various alternatives of neem oil that will keep your plant safe without affecting the buds’ flavor profile. Here are some alternatives to neem oil for cannabis:

  • Horticultural oils
  • Alcohol and water solution
  • Insecticidal soaps
  • Diatomaceous earth
  • Picking the insects off your plant manually

Is Neem Oil Safe for Me and My Pets?

Yes, for most people, neem oil is relatively safe. As per the Environmental Protection Agency of the US, neem oil falls under the low toxicity substance class — it is rarely fatal for mammals, including humans. 

However, it can still cause skin irritation if you have sensitive skin or allergic reactions. So, to ensure neem oil is safe for you, here are a few steps you can take:

  • If you have sensitive skin or allergies, wear gloves and masks when using neem oil
  • Do not drink neem oil or add it to food as ingesting even 20 ml can cause convulsions and vomiting and it can also affect your liver and fertility
  • Keep neem oil away from pregnant women, children, and pets

But Isn’t Neem Oil Good for Health?

Yes, neem oil has several health benefits. It is believed to help with various conditions like dry skin, skin wrinkles, scars, acne, warts, inflammation, fungal infections, etc. However, there is not enough research and study to support these health benefits. While there are many reports of neem oil helping people, it is still not safe to consume unless mixed with some other compound.

If you want to use neem oil for health benefits, please consult a professional before using them. And if you want to use it on the skin, carry out a patch test with diluted neem oil before using it to treat your skin condition. 

Summary: Is It Worth Using Neem Oil to Control Pests in Cannabis Plants?

To summarize, neem oil is really effective to deter pests on cannabis plants and it is totally worth using. Yes, it does not kill pests on contact, but by making the pests starve and keeping them from reproducing, it can effectively reduce the number of pests on your cannabis plant quickly. 

The best feature of neem oil is that, while being effective against pests, it is safe for your cannabis plant as long as you don’t drench your plant in it or use it during daylight hours. However, you must avoid using it on your buds as it can affect the flavor profile with its pungent aroma. 

If you want to deter pests on your cannabis plant, you should consider using neem oil. Apart from being an effective pesticide, it is also an effective way to fight mold and fungal problems in your plant. It is so effective that even severe fungal problems, like slimy roots, can be fixed with a little bit of neem oil.

And making your own neem oil isn’t difficult. You can use the recipe mentioned above and make your homemade neem oil pesticide within an hour. But if you want to make a milder or stronger solution, feel free to change the ratios as per your needs.

But remember to always do a patch test on your cannabis plant before using it on the entire canopy as sometimes cannabis plants tend to negatively react to the solution by developing spots, discoloration, or other signs of stress. 


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