Best Organic Pesticides for Cannabis Plants

Growing cannabis comes with its fair share of visits from pests, from aphids to caterpillars, that can seriously damage your plants. And when they pay their visit, many growers reach for chemical pesticides. But you shouldn’t make the same mistake. 

Chemical pesticides can leave harmful residues, are harmful to the environment, and can sometimes even be problematic to you, your children, and pets. Instead, you need to consider using organic pesticides that are safer. 

In this article, let’s look at some of the best organic pesticides you can use to kill pests on your cannabis plant. 

Understanding the Enemy: Common Cannabis Pests

Before you even start tackling the issue, it’s crucial to know what you’re up against. Not all pests are created equal, and they attack your plants in different ways. So, let’s break it down — what kinds of pests are out there, and how exactly do they wreak havoc on your cannabis?

To keep things simple, here are the main types of pests you’ll want to watch out for:

• Sucking Pests

These little suckers (pun intended) feed on your plants by drawing out the nutrients they need to grow. As a result, your plants can end up stunted and weak, and the yield can take a serious hit.

• Chewing Pests

These guys are like tiny lawnmowers, chomping away at leaves, branches, and even your precious buds. Left unchecked, they can do some serious damage in no time.

• Infectious Pests

As if chewing and sucking wasn’t bad enough, some pests spread diseases. These can infect your cannabis crop and lead to a reduction in both quality and quantity.

The biggest culprits you’re likely to encounter include spider mites, fungus gnats, aphids, caterpillars, slugs, snails, and thrips. But that’s not the whole list — there’s a whole host of other creepy crawlies that can cause problems.

Want a pro tip? Talk to other growers in your area. They’ve probably already dealt with the pests you’re likely to face, so you’ll know exactly what to prepare for. Pests may be a pain, but they’re pretty predictable once you know what to look for.

Best Organic Pesticides for Cannabis 

Now that you know what pests to look for, let’s talk about solutions! Organic pesticides are your best friend when it comes to protecting your cannabis without compromising its quality. They are safe for the plant, you, and the environment. 

So, let’s start with the best organic pesticides you can use for your cannabis plant. 

• Neem oil 

Neem oil is a fan favorite among growers, and for good reason. It’s a natural, organic pesticide that’s not only effective but also safe for you, your pets, and your plants. Plus, it doesn’t harm the good bugs like ladybugs and honeybees, so it keeps the ecosystem balanced.

When it comes to getting rid of the bad guys, neem oil is a pest’s worst nightmare. It takes out aphids, crickets, mites, caterpillars, fungus gnats, grasshoppers, thrips, spider mites, and many more. It even fights mold and fungus, making it a great all-rounder for your garden.

Using neem oil is pretty straightforward. You’ll want to dilute it with water according to the instructions on the bottle. This step is crucial — if you skip it, your grow room might end up smelling like neem for days (and that’s not exactly pleasant).

Once it’s mixed, grab a sprayer or mister and apply it evenly across your plants. Here’s a tip: spray it right before the lights go off or at dusk to avoid burning your plants. If you absolutely have to spray during the day, make sure to use fans to dry the leaves quickly.

For an extra boost, mix the neem oil with soap water. Even if the packaging doesn’t mention it, this helps the oil spread evenly without settling on the leaves and causing buildup.

While neem oil is awesome, it’s not for everyone. If you’re growing for someone else, especially medical patients, be cautious. Some people are allergic to neem, and trace amounts could end up in the buds. Always check with the end user before using it.

Also, never spray it on the buds. Neem has a very pungent odor and it can rub off on the buds, altering the final flavor and aroma profiles of your precious flowers. 

• Diatomaceous Earth 

If you’re looking for something super simple yet effective, diatomaceous earth is a great option. It's basically just fossil dust, but don’t let it fool you — this stuff works wonders when it comes to pest control.

Diatomaceous earth is harmless to your plants and us, but it's a different story for bugs. 

On a microscopic level, this powder is like tiny shards of glass. When pests come into contact with it, the sharp particles tear through their exoskeletons, causing them to dehydrate and die. Sounds brutal, doesn’t it? 

All you have to do is sprinkle diatomaceous earth on your soil and around your grow room. It’s easy to apply and stays effective as long as it’s dry. The downside? It won’t completely wipe out a pest infestation, but it’s perfect for reducing their numbers when you use it alongside other organic pesticides.

• Spinosad 

Spinosad is another awesome organic pesticide that gets the job done without harming your cannabis plants, pets, or even kids. It’s made from naturally fermented bacteria that target the nervous systems of pests, effectively eliminating them.

This organic solution works by attacking the nervous system of common cannabis pests like crickets, grasshoppers, caterpillars, thrips, aphids, spider mites, and whiteflies. Once the pests come into contact with Spinosad, they are quickly paralyzed and die.

To use this, all you have to do is mix Spinosad with water and load up your pressure sprayer. Pay special attention to the areas where bugs love to hang out, especially under the leaves. 

You can be fairly generous with the application since the spray is pretty diluted. Just remember, once mixed with water, it only stays effective for about a day, so make small batches and use it up right away.

• Caterpillar BT Spray

Are caterpillars munching away on your precious cannabis leaves? Time to bring in the heavy artillery — Caterpillar BT spray. 

This biological insecticide packs a punch as it contains Bacillus Thuringiensis (BT), a bacteria that’s lethal to caterpillar larvae. The spray not only kills these leaf-loving invaders but also keeps mature caterpillars from turning your plants into a pantry.

There are different types of BT sprays, but you’ll want one specifically designed for caterpillars. It also works on leaf miners, moths, and inchworms.

The minute you spot any sign of caterpillars on your plant — like chewed-up leaves or droppings — grab your BT spray and start spraying. Apply it weekly until you’ve won the war against caterpillars. The best part? It’s totally safe to use all the way up until harvest, so your buds stay untouched.

• Horticultural Oils 

Some plants naturally repel pests, and you can use that evolutionary power with horticultural oils. These oils are concentrated from plant compounds and minerals known for their pest-killing and repelling abilities. 

Using horticultural oils is a breeze. Just grab a mister, spray your plants, and let nature do the rest. While the oil only remains active for about eight hours, consistent spraying can help fend off pests like barnacles, aphids, spider mites, and whiteflies.

Plus, unlike some other strong pesticides, horticultural oils don’t leave a residue behind. This means your plants won’t have any gross film on them, and the oil won’t interfere with their growth. 

How to Use Organic Pesticides Effectively on Cannabis Plants

To get the best benefits out of organic pesticides on cannabis, you need to apply it properly so you don’t harm yourself, your plants, nature, and pollinators. While organic pesticides are generally safe, you must use them wisely to avoid causing more harm than good to your cannabis plants. Here’s how to guarantee that your organic pesticides work and play nice with nature.

1. Always Identify the Pest First 

Before using any pesticide, be it organic or synthetic, you need to first identify the pest that's attacking your cannabis. If you misidentify and attempt the wrong treatment, you will waste time and resources on something that can potentially compound the problem further, making your plant worse off. If you apply the wrong solution, you may damage your plants as it will help one pest but not the real culprit.

For instance, spraying neem oil that works against soft-bodied bugs like aphids will have no impact on fungus gnats which need treatment for their larvae in the soil. If you use the pesticide incorrectly, you may end up with an untreated infestation. This ends up stressing out your cannabis and wasting precious resources.

Remember, every pest attacks plants in different ways and cannabis is no different. Some insects suck the plant's sap, which weakens its ability to absorb nutrients. Other types of pests destroy the leaves, stems, or roots which have a debilitating effect on the plant. Each pest needs specific treatment. So, what treats aphids may not work on spider mites and some pests may be completely resistant to treatments. 

Here's a quick overview of how to identify pests:

• Spider Mites: Look for little webs found in between the leaves and stems. They are small and you can’t identify them easily, so you’ll need a jeweler's loupe or a microscope. Also, look for small holes or teeth marks on the leaves. 
• Aphids: These are small soft-bodied insects that are found in clusters on the buds and leaves. Leaves affected by these pests may start curling or turn yellow. You'll also find ants in the vicinity as they are attracted to the honeydew — a sticky substance produced by aphids — and protect them from predators. 
• Whiteflies: These are tiny fluttering insects with white wings. They usually hide on the underside of leaves and feed on leaf tissue which can cause leaves to droop or turn yellow.
• Fungus gnats: These are small black flies often found near the soil. Adult gnats do not harm plants directly but the gnats’ larvae damage cannabis roots and cause stunting and yellowing.
• Thrips: Thrips are tiny slender insects that cause silvery or bronze streaks on the leaves. You might spot black specks plus their droppings on leaves.

Also, you’ll do yourself a huge favor by preventing the pests rather than trying to eliminate them. This means that you'll have to check the plants regularly to find the pests before they become a big problem. 

Here are some techniques for proper pest identification: 

• Use a magnifier: Many pests like spider mites or thrips are too small for the naked eye.  A magnifying glass, as mentioned earlier, can help you see them earlier under the leaves or at the node of the leaf, for example. 
• Give the undersides of leaves a glance: Aphids, whiteflies, and spider mites prefer to position themselves on the undersides of leaves, where they can feed and breed.
• Don't forget the stems and roots: Look at the leaves but don’t forget to also look at the stems, roots, and soil too. Some pests like fungus gnats, for instance, are much more visible near the roots, as their larvae could be hiding there. Look at the soil closely for larvae, adult gnats, or anything unusual.  
• Look for specific symptoms: Make sure to look for specific symptoms as certain pests have distinct feeding habits that leave very specific symptoms. Pest damage shows up in lots of ways like discoloration, stippling, curling, or stunting of the leaves.

If you're unsure, don't hesitate to get help, especially when you're unable to determine what's bothering your plants. You can ask local growers or other growers on our site or use apps to identify the pests properly. Rather than misidentifying the pests, you can just get help, do your research, and then proceed to fix the problem. 

2. Do Your Homework 

A little research can go a long way. Before trying any new pesticide, double-check its effects and consider getting advice from experienced growers. 

It is not enough to choose any old organic pesticide off the shelf if you want to protect your cannabis plants. Not every product is fit for every pest. Each organic pesticide targets certain pests specifically. If you use the wrong product, pest problems can get worse, an infestation can develop, and in some cases, your cannabis plants may be harmed. 

Neem oil can potentially eliminate problems such as aphids and spider mites, but it can actually enhance the problems presented by fungus gnats and caterpillars. Bacillus thuringiensis (BT) is valuable to control caterpillars but does nothing to sucking pests like thrips or white flies. 

There are many kinds of organic pesticide too; each pest has a different pesticide effective under different conditions. The effect of the pesticide also varies according to the maturity of the plant. By thoroughly researching before using a pesticide, you will make sure that you apply the right product at the right time to limit the risk to your plants and maximize the control of pests. 

Along with your pest of concern, other factors like the stage of growth of your plant also play a part. Some pesticides can be too strong for seedlings or young plants and can leave undesirable residues on buds if used too close to harvest. 

3. Follow Instructions Properly

The instructions printed on organic pesticide product labels are in place for a reason. Though they may feel like a suggestion, the pesticides are tested thoroughly to ensure efficiency and product safety. Therefore, you must follow the instructions closely to deal with pests and avoid damaging your plants. 

The advantage of using organic pesticides is that they will kill the pests but won't harm the plants or the environment. The label is going to tell how to mix the pesticide, how to apply it, how to store it, and also how often to apply it. You can end up with poor pest control, damage to your plants, and even health or environmental issues from doing anything outside of these parameters.

In addition, remember not to overuse them either. Pesticides, even if they are organic, can cause sufficient harm. For example, if you use concentrated organic pesticides like neem oil without diluting them properly, it may lead to a leaf burn. The oils can clog the plant’s stomata (pores), which will impact its breathing and ability to get sunlight. On the flip side, if you under-dilute the pesticide, it will not be effective. And, the pests will continue damaging your cannabis.

Many organic pesticides need diluting as they are concentrated. The product’s label will indicate the proper ratio to water. In any case, using a stronger concentration than recommended can cause leaf burn, slow down growth, and in some cases even death of a plant. This is especially true with oil-based products like neem or insecticidal soaps. On the other hand, weak pesticides may not work effectively on pests because of under-dilution.

Always measure the amounts carefully, and mix in non-reactive containers that are clean. It’s a good idea to use distilled or filtered water to prevent possible interference from chemicals in tap water.

The instructions also tell how to do the application, whether it should be sprayed over the leaves or applied to the soil. Some products may even specify which part of the plant to target like the undersides of leaves where many pests are hiding. It is important to follow these application instructions so the pesticide reaches the pests.

If the directions say to apply under the leaves, use a fine mist sprayer to completely reach these areas. When you apply it just to the tops of the leaves, many pests will not be affected.

Organic pesticides usually have to be applied more often than synthetic ones as they degrade naturally. The label will tell you when to re-apply for continued protection. If a pesticide is applied too much, then that chemical will build up and stress the plant. If it is under-applied, then the pest may bounce back and cause injury before the next application.

Try to follow the suggested application intervals and don’t be tempted to apply more than necessary or it will not only harm the plants but also mess with beneficial creatures in the eco-system.

Also, the label will have instructions indicating the best conditions for application depending on the climate. If you don't follow these guidelines, the pesticide may not work or it may be harmful. For instance, using neem oil in bright sunlight can create phototoxicity. When the neem oil heats up, it harshly burns the leaves. Thus, always follow the timing suggested if you want to apply pesticides. Early morning or late afternoon is usually ideal because heat stress is avoided and evaporation is minimal. Try not to spray on windy days, which can cause uneven application or pesticide drift.

Finally, although organic pesticides may be safer than synthetic pesticides, safety practices must be followed according to the label. You should wear gloves, masks, or goggles and also avoid contact. Certain organic substances can cause hay fever, skin irritations, or other serious health problems.

Be sure to put on the recommended safety gear every time you use pesticide, even if it says “safe” or “natural”. Wash your hands thoroughly when done and make sure you don’t touch your face while spraying.

4. Avoid Mixing Pesticides 

Combining organic pesticides to fight off multiple pests at once may sound smart, but it often backfires and causes more issues with your plants than the pests you’re trying to fix.  Each organic pesticide is designed for a specific pest or problem, so mixing them can put the plant under stress and cause toxicity and damage. 

For instance, neem oil, insecticidal soaps, or BT are designed to work at specific concentrations on specific pests only. When these substances are combined, they may react chemically in unexpected ways while changing their physical characteristics, making them ineffective or creating harmful substances as a byproduct.

This is because different pesticides contain active ingredients to kill specific pests, but they may stress out cannabis plants when mixed. Neem oil is an oil-based pesticide that can coat the leaves and interfere with their ability to “breathe.” If you apply another substance on the leaves similar to neem oil, like other horticultural oils, for instance, it can further clog the stomata or cause an overdose of active ingredients, leading to phytotoxicity. The signs will be visible on the leaves as well and the leaves turn yellow or look burnt. 

In addition, pesticides like BT work best as a single ingredient. You should not mix BT with another pesticide, particularly oil-based ones like neem as it can coat the bacteria and prevent it from reaching the pests, making the pesticide almost useless.

Another reason why you shouldn't mix pesticides is that they can harm other beneficial insects like ladybugs, predatory mites, or bees if used incorrectly.  Mixing many pesticides will create a toxic environment which can be deadly to the pests as well as the helpful organisms that protect your cannabis plant naturally. This messes up the natural balance in your grow tent, possibly leading to even more pest trouble in the future.

Finally, don't forget that although organic pesticides are made from ‘natural’ substances, they may react with one another to produce toxic compounds similar to those made in the lab. It can also alter the pH erratically at times and cause problems for plants. 

If you have no choice other than to use several pesticides, you should do it carefully. Still, don't mix them; instead, apply them separately at intervals. This enables each pesticide to operate alone and allows your plants to recuperate from each treatment. For instance, if you've used neem oil this week, use BT next week to keep your plants safe from pests. This method stops the chemicals from mixing with each other and reduces the chances of them overloading your plants.

Ensure you keep a schedule or calendar of your pesticide applications to monitor your plants and avoid over-application.

5. Test Before You Spray 

Always do a small patch test when trying a new pesticide on your cannabis. Each plant can react differently, and it’s better to see how it responds on a small scale than to risk damaging your entire crop.

6. Check for Side Effects 

Make sure to understand any potential side effects the pesticide could have on your plant. Some organic pesticides can leave behind residues, so you want to ensure your buds remain safe for everyone to enjoy.

By following these tips, you'll keep your plants — and your harvest — healthy while making sure your pesticide use is on point.

Summary: Best Organic Pesticides for Cannabis Plants

Pests are truly a nuisance for any cannabis grower, but organic pesticides like neem oil, diatomaceous earth, and horticultural oils can effectively protect your plants without harmful chemicals. By identifying pests early and using these solutions properly, you’ll keep your cannabis healthy and your harvest safe.