Neem Oil or Hydrogen Peroxide? What's Best For Cannabis Plants?

As a cannabis grower, you will come across two organic compounds that are very much in use in most cannabis gardens. Both hydrogen peroxide and neem oil are often promoted as the best insecticides for cannabis plants, and sometimes, for the other benefits they offer. 

But which one is better between the two and which one should you have in your cannabis arsenal? Find out everything about neem oil and hydrogen peroxide and which one is best for you in this article. 

What is Hydrogen Peroxide?

Hydrogen peroxide is a naturally occurring compound, and at a molecular level, it is quite similar to water. Water is H2O and hydrogen peroxide is H2O2, i.e., it has an extra oxygen atom. 

Hydrogen peroxide is blue in color in its purest form, but you will likely never come across it unless you are building rockets. Instead, what you will find at local stores will be significantly diluted H2O2, which appears like water. 

This chemical is an excellent substance that has many uses across industries. In its most diluted forms, it can be used as a home remedy for scrapes, bruises, and cuts, thanks to its antiseptic properties. 

On the other hand, hydrogen peroxide in its highly concentrated, blue-colored form is used as rocket fuel since it is extremely flammable. This is why you won’t find concentrated H2O2 easily. 

In the middle of the spectrum, mildly concentrated H2O2 is what you’ll need when you are growing cannabis. Here, it can work as a disinfectant that keeps your gardening tools clean, the soil fluffy, and pests at bay. 

Hydrogen Peroxide Production

Hydrogen peroxide occurs naturally in nature, but that won’t be the same compound you’ll purchase. There’s not enough of it in nature to be packaged and sold to gardeners like us. So, the compound you’ll purchase will be synthetic in nature but it retains the same qualities of the naturally occurring H2O2 — nothing to worry about 

Alexander von Humboldt formulated one of the world’s first synthetic compounds ever in 1799 called barium peroxide. In 1818, Louis-Jacque Thenard figured out that he could produce oxygenated water with barium peroxide. This was hydrogen peroxide, water with an extra atom of oxygen. 

In the next century, experts figured out better ways to produce hydrogen peroxide using sulfuric acid and hydrochloric acid, but that process is now obsolete in most industries, too. Today, hydrogen peroxide is produced through a process called anthraquinone, which was patented in 1939 and is regarded as the most efficient and economical production method for this compound. 

What is Neem Oil?

Hydrogen peroxide is more on the industrial side, but neem oil sits on the other end of the spectrum. If you grow plants or have a relative in India, you may have already heard about neem oil and its various benefits. 

For gardeners, neem oil is one of the best pest control and prevention products out there. Plus, it is organic and does not damage the plant either, provided you follow the instructions properly and dilute it. Using concentrated neem oil is not a good idea. Neem oil has also been used for centuries for various other benefits it offers, including health benefits for humans as it is a remedy for fungal and bacterial diseases and various skin infections. 

Essentially, this compound makes it difficult for pests to reproduce and live as opposed to killing them on contact. The pests move out of your garden and look for a new home. 

Neem oil is extracted from the Azadirachta indica, a plant that’s native to India but has since traveled to other tropical and subtropical regions for its farming and medicinal benefits. 

Neem oil is easy to produce, and back in the day, people produced neem oil by manually grinding the fruits and seeds of the neem plant. Large-scale manufacturers use solvents to extract the soil in large quantities, but this does take a hit on its quality. 

Neem oil contains many active compounds like Azadirachtin. It is the primary compound found in neem oil and has been extensively studied for its strong insect-killing properties. It is particularly effective against pests as it works by disrupting their feeding process. It also interferes with their reproductive process, thereby impacting their growth and ability to lay eggs. This disruption works amazingly as the pests can no longer thrive. 

Azadirachtin effectively combats a vast range of pests including aphids, spider mites, caterpillars, whiteflies, and more. Once you apply neem oil to plants, azadirachtin makes it less appealing to insects. In addition, it repels pests and discourages them from lurking in treated and surrounding areas. 

Neem oil also contains a wide variety of limonoids such as salannin, nimbin, and nimbidin apart from azadirachtin. Essentially, limonoids are phytochemicals present in plants, and some of them like azadirachtin work as antifeedants as you already know. These secondary metabolites are also antibacterial, making them effective against specific types of bacteria. Some research suggests that neem limonoids may possess antiviral effects although further studies are still ongoing to understand this aspect. The combined action of azadirachtin and other limonoids in neem oil creates a lethal effect against pests. 

Benefits: Neem Oil vs Hydrogen Peroxide 

When it comes to organic pesticides and supplements, neem oil and hydrogen peroxide are often on the top for the benefits they offer. While they do have some similarities, they differ a lot in the benefits they offer to cannabis growers. Let’s look into the benefits and see how they fare in this regard. 

1. Preventing and Eliminating Pest Infestations 

The primary reason both neem oil and hydrogen peroxide are so widely regarded is because they help growers deal with pests in the garden. However, neem oil and hydrogen peroxide work in different ways, so you need to pick one that suits you better. 

Hydrogen Peroxide

Hydrogen peroxide is a terrific solution for eliminating common pests that attack cannabis plants often. Since it is antiseptic in nature, the compound helps disinfect the plant and even the soil, thereby removing the pests from the plant. 

When used as a foliar spray, hydrogen peroxide eliminates pests living on the plant, especially on the leaves, by making the zone inhabitable for them. It does not necessarily kill pests on contact but is fairly effective; it does kill their eggs on contact though. 

Additionally, you can also use hydrogen peroxide in the soil to kill pests living within the soil. As a soil drench, it is quite effective, too. It can also help prevent pests from coming onto your cannabis plant. 

Plus, hydrogen peroxide is completely safe for your cannabis plant. You can spray it down and use it as a soil drench, and as long as you use the right ratios, you don’t have to worry about damaging your cannabis plant.

But there is one downside to hydrogen peroxide here — it is not a quick solution and, depending on the severity of the infestation, you may have to reapply it or even add another organic pesticide for better results. 

Another downside of hydrogen peroxide is that it can sometimes deter beneficial pests, like butterflies, praying mantis, and ladybugs, too. This is not always ideal if you want a thriving ecosystem around your cannabis plant. 

Neem Oil

On the other hand, neem oil offers a much better proposition in dealing with pests. Neem oil is rich in azadirachtin, a compound that affects insects in two ways. First, it hampers their feeding, so many of them starve or move out of the plant. 

Second, it interferes with their hormonal and reproductive systems, rendering them unable to grow or lay eggs. As a result, the pest population fails to grow and the pests either move out or their numbers dwindle within a few days, 

Some experts also suggest that neem oil creates an oily coating on the pests’ shells, which stops them from breathing, but this is not always the case. Plus, neem oil is effective against a wider spectrum of insects. 

As good as neem oil is, it also has a major downside. It cannot be used on a flowering cannabis plant. Neem has a fairly pungent odor and harsh flavor profile, so it shouldn’t be used on a flowering cannabis plant. 

Another benefit of neem oil is that it is fairly safe for beneficial insects. Neem oil does not affect most beneficial insects like bees, rove beetles, earthworms, ladybugs, etc., so you can use it without worrying much. 

During other stages of your plant’s life, neem oil is completely safe in moderation, but if you were to use it on your flowering cannabis plant, don’t be surprised if your cannabis buds develop a pungent flavor and aroma profile. 

Which is Better?

For a cannabis plant that has not yet reached bloom, neem oil is arguably more effective at dealing with pests. However, considering how it can affect flowers on cannabis, it should be avoided during the flowering stage. 

That is where hydrogen peroxide comes into play. We wouldn’t use hydrogen peroxide as the first choice when we have neem oil available, but when the latter is not an option, the former can be quite helpful. 

Remember, both neem oil and hydrogen peroxide only fix the problem, they don’t eliminate the root of the problem. For that, you need to figure out how pests are getting into your garden and stop that from happening. 

You can use neem and hydrogen peroxide in a sequential manner where you apply the neem oil first to fight pests. Then, you can add hydrogen peroxide as it can reduce the risk of powdery mildew and mold. By alternating treatments, the likelihood of pests developing resistance is limited. In addition, timing plays a key role in addressing both pests and potential diseases. So, you should identify the problems and treat them before it’s too late. 

Some people mix both neem oil and hydrogen peroxide, but we are unsure about how this could work. 

2. Fungal Infestation, Root Rot, or Slimy Roots

Fungal infections on cannabis plants are more common than you’d think, and usually, they come in the form of root rot, slimy roots, or moldy buds. This can create havoc for your cannabis plant and, if not treated on time, can even kill it. Let’s see how neem oil and hydrogen peroxide can help you here.

Hydrogen Peroxide 

Hydrogen peroxide has disinfectant properties, so it is quite effective at killing fungal spores. All you need to do is make a 3% H2O2 and water solution in a 1:2 ratio and either use it as a soil drench or foliar spray. Hydrogen peroxide can fix most of these issues without any fuss.

However, it should be noted that if you’re using hydrogen peroxide as a soil drench, you should be careful and only use it as a last resort. It is so effective it can sometimes deplete the soil of beneficial fungi and bacteria. 

Hydrogen peroxide can even come in handy to remove bud rot to an extent. Many growers dip their freshly harvested buds in hydrogen peroxide to eliminate any mold and fungal spores within them. 

However, we don’t recommend this. Moldy buds are never worth it and if you find mold in your cannabis buds, it’s always better to toss the buds in the bin and start anew. Mold can have nasty side effects on your body and leave lasting problems. 

Neem Oil

On the other hand, neem oil can be quite effective at treating mold and fungal infections in cannabis plants, including slimy roots. Here, neem oil hinders its ability to reproduce, thereby preventing the problem from growing. 

Plus, neem oil is an effective disinfectant, like hydrogen peroxide, that can help you clean your cannabis plant, its roots, and the growing medium. 

Again, you can use neem oil on your cannabis plant in its growth stage, but you should not use it if it is in its flowering stage. Neem oil will kill the fungal infection but it will also change the flavor profile of your cannabis buds, as mentioned above. 

Which is Better? 

Here, hydrogen peroxide is the better option since it is very versatile and can be used on a flowering cannabis plant — as long as you are careful. Yes, it can hamper the microbial life in the soil, but you can always restore it with supplements. You can’t restore your buds’ original flavor once neem oil has influenced it. 

3. Other Benefits That Are Exclusive to Hydrogen Peroxide 

Apart from being a terrific fungal disinfectant and an insecticide, hydrogen peroxide offers many other benefits that neem oil does not. Let’s take a look at the common ones. 

• Seed Prep

Hydrogen peroxide can help you clean your cannabis seeds and remove any pathogens that may have hitched a ride on them. This will ensure that the seed you grow does not grow with problems and gets a clean start.

Some expert growers also claim that hydrogen peroxide can also improve the germination rate of your seeds, but these claims are purely anecdotal and may or may not work for you. Here, all you need to do is soak your cannabis seeds in a hydrogen peroxide solution for a bit before germinating it. 

• Water Treatment 

Hydrogen peroxide can also help treat your water before it gets to the cannabis plant. Generally, growers use bleach or other synthetic compounds to treat water but they end up doing more harm than good. 

Instead, hydrogen peroxide will keep the water free of pathogens and safe to use on your plants. However, it is still recommended that you try other alternatives like sand filters and charcoal filters before moving to hydrogen peroxide. 

• Bud Washing 

As mentioned above, hydrogen peroxide can be used to wash cannabis buds. For this, you need 3% H2O2 solution mixed with water, dip your buds in it for half a minute, and let it dry. 

While we don’t recommend washing buds to remove mold, you can still wash your buds to clean them off pests, dirt debris, and other contaminants that may have landed on the buds. Be sure to dry them properly afterward to prevent mold from getting on them. 

• Improve Hydroponic Growth 

Finally, hydrogen peroxide has a benefit for hydroponic cannabis plants that function on closed-loop irrigation systems. Here, you can add a bit of hydrogen peroxide to the water to oxygenate it, so the roots don’t have to struggle for oxygen. Additionally, it will keep the water and plumbing components of your hydroponic setup clean!

How to Use Hydrogen Peroxide on Cannabis Plants?

Hydrogen peroxide is fairly easy to use on cannabis plants, but you need to keep a couple of pointers in mind. There are two ways of using hydrogen peroxide, one as a foliar spray and another as a soil drench. 

Most times, you will use hydrogen peroxide as a foliar spray, especially if you are dealing with pests and fungal infections. Here, you need to mix one tablespoon of 3% H2O2 in a cup of distilled water. Then, you can use a fine mister to cover your plant with it — you can be liberal. 

If you are drenching the soil with you to fix root rot or eliminate pests, you can use the same ratio mentioned above and water your plant normally. If it’s possible, you should also consider wiping down the roots with hydrogen peroxide to eliminate the mold properly, but this may not be possible for soil-based cannabis plants.

There are many uses of hydrogen peroxide in a cannabis garden, but those depend on your setup and goals. So, before using it for other things like cleaning the water or disinfecting the hydroponic system, you should conduct thorough research to figure out what will work for your particular setup. 

How to Use Neem Oil on Cannabis Plants?

Like hydrogen peroxide, neem oil is relatively easy but has a few extra steps during preparation. For starters, you need to ensure your neem oil is 100% and produced with a cold-pressed technique — hot pressing eliminates azadirachtin from it, so it won’t be as effective. 

Since it is oil, it won’t mix well with water directly. You need an emulsifying base for it. You can use organic soap, potassium-based insecticidal soap, or silica to mix it with water. Once the oil is mixed with the emulsifier, add it to water and mix well. 

The ratio depends on your preferences, but if you are just starting out, you can mix 4 tsp of neem oil in 1 tsp of emulsifier and add it to a gallon of water. Then, you can either use a fine mister to spray it on your plant or water it on your plant; the latter should last for 20 days. 

What are the Risks of Using Hydrogen Peroxide and Neem Oil?

Neem oil and hydrogen peroxide are superb to have at your disposal, but you must be careful while using both of them. Both possess some dangers that can hurt your cannabis plant. Let’s take a look at them. 

Hydrogen Peroxide Risks 

Hydrogen peroxide, if handled incorrectly, can do more damage than good. For starters, it can damage the beneficial microbial life within the soil since it does not discriminate. It’s an effective disinfectant that will eliminate as much microbial life as it can. 

Next, you should store hydrogen peroxide in a dark cabinet and not expose it to light often. It will degrade quickly in light and won’t be as effective. 

In addition, try not to heat your hydrogen peroxide solution even in its diluted form. This is because a lot of factors including oxygen degradation come into play. The boiling point of H2O2 is about 302.4°F or 150.2°C. Once it reaches this temperature, it will show a violent reaction. So, it’s best not to take a chance. You need to handle it with immense respect no matter what, and always keep it away from any heat source or open flame. 

If you’re using anything more than 3% H2O2, you should be more careful. It has the potential to combust or break down under specific conditions. As a strong oxidizing agent, it can generate heat when it breaks down, making it exothermic. This reaction results in the formation of water (H₂O) and oxygen (O₂). The oxygen released during this process can support combustion. Therefore, sometimes, the heat produced during decomposition can sustain the reaction on its own. 

Several factors influence the likelihood of hydrogen peroxide combustion:

1. Concentration: Concentrated hydrogen peroxide is susceptible to decomposition. Thus, as a regular gardener or someone who uses hydrogen peroxide for household purposes, you have nothing to worry about. This is because regular household hydrogen peroxide solutions (around 3%) are less reactive compared to industrial solutions.
2. Temperature: High temperatures accelerate the breakdown of hydrogen peroxide. It's best to store it in a cool, dry environment to maintain stability.
3. Contaminants: Impurities or contaminants like metal ions (catalysts) can expedite the decomposition process of hydrogen peroxide.
4. Confinement: If hydrogen peroxide is confined or restricted in any way, pressure can build up due to the oxygen that’s released, leading to a dangerous hazardous reaction.

So, how does this apply to diluted solutions used in households? Is there a risk?

Not really. Household hydrogen peroxide solutions, which are commonly available in pharmacies or stores typically have a concentration of around 3%. At these concentrations, the risks associated with pressure buildup and combustion are reduced compared to concentrations used in industrial applications.

This means that the possibility of pressure buildup and a dangerous reaction due to oxygen release is generally lower when working with diluted solutions of hydrogen peroxide. Diluted solutions of hydrogen peroxide are less likely to undergo decomposition. However, this doesn’t mean that the risk is eliminated. Just that it’s lower. As a precautionary measure, never heat hydrogen peroxide. Simply keep it away from fire. In addition, do not mix it with other solutions, especially if it’s incompatible. If you want to mix it with anything, it’s best to read up about it to avoid issues. 

It is a good idea to also wear rubber gloves when handling hydrogen peroxide. In some people, it can irritate the skin and even burns (rare but possible). So, unless you’ve diluted it in water, do not handle it with your naked hands. 

Neem Oil Risks

On the other hand, neem oil is fairly safe. However, it can have some side effects on your cannabis plant. 

So, it is recommended that you do not use neem oil during the flowering phase of your cannabis plant since it can leave a nasty odor on the buds. Plus, the pungent odor can even force the bugs to hide in the buds — the task failed successfully. 

Additionally, you should not use neem oil in seedlings as they cannot handle it properly. Neem oil is best suited for plants that are over a month old and not flowering yet. 

You should also not use neem oil in the following circumstances:

• Your cannabis plant suffered from nutrient deficiency, watering stress, or nutrient toxicity 
• The temperature is too hot or cold 
• The lights are on — instead, use it before you turn the lights on 
• Your plant is three weeks from harvest — stop using it after this point 

Azadachtrin

If you use neem oil according to the recommended guidelines, the active compounds present in neem are generally not toxic to humans, pets, and beneficial insects. This is why neem oil has been preferred for centuries. Most insecticides and pesticides tend to harm even the beneficial bacteria present in the soil and impact soil health but neem oil doesn’t do that. 

However, there are some concerns regarding the active compound azadirachtin present in neem as to whether it could be a carcinogen. However, there’s no conclusive proof. It’s considered harmless if you use it according to the recommended levels. More information from the University of California Agriculture and Natural Resources states that it’s not toxic. Most importantly, the US EPA lists it as non-toxic. 

Plus, the concentration also matters. Typically, the products available for gardeners don’t exceed more than 3%. Most formulations contain only about 1%. Commercial growers can access neem oil with more than 5% azadirachtin. 

The amount of azadirachtin in neem oil can vary depending on factors such as how it's extracted, which part of the neem tree is used, and the manufacturing process. However, neem oil usually contains a mixture of compounds with azadirachtin being one of the active ingredients responsible for its insect-killing properties.

In commercial products, the concentration of azadirachtin is often standardized to ensure consistency and effectiveness. The amount of azadirachtin is typically stated as a percentage on the product label. Therefore, read the instructions on the product label carefully and follow the manufacturer's recommended application rates.

Coming to neem oil’s safety aspect for you, it is fairly safe. It is rarely fatal for mammals, but it can still cause skin irritation if you have allergies or sensitive skin. And despite being in use as a medicine for centuries, it is not advised that you consume it without first checking with your doctor. 

Even 20 ml of neem oil can cause vomiting and convulsions, and over time, it can affect your liver and reduce fertility. So, keep neem oil away from children and pets, too. 

If you want to use neem oil on your skin to deal with wrinkles, scars, inflammation, or fungal infection, you can, but you should do a patch test first with a diluted sample to ensure your skin does not react to it. 

Summary: Neem Oil or Hydrogen Peroxide? What's Best For Cannabis Plants?

The correct answer is both. Yes, neem oil and hydrogen peroxide serve common purposes, but the latter offers additional benefits that the former does not. At the same time, both are supposed to be used at different times. 

Hydrogen peroxide is safe for flowering plants but it may not be as effective as neem oil, and on the other hand, neem oil is more effective but it can only be used on growing cannabis plants, not seedlings or flowering ones. 

So, keep both in your arsenal. They are excellent products that can come in handy at different times.