Organic Cannabis Pest Control: How to Keep Bugs Off Your Nugs

Last Updated on August 8, 2023

Imagine this: You are stoked to finally, legally grow your own organic cannabis at home. You pridefully raise your babes from seed or clone, diligently tend to them for months – fawn over them even – only to find your nugs full of bugs at harvest time. Wah-wah-wah. Awful! The worst part is, that is how it usually goes down! Most often, you don’t even realize you have a pest problem until you are trimming, or pulling apart buds to enjoy them – when it’s already too damn late to implement a cannabis pest control program! Sure, sometimes there will be earlier or more obvious issues, visible pests, and foliar damage. Yet pests seem most drawn to the sweet, sticky cannabis flowers more so than the leaves. Just like we all are, am I right?

Let’s talk about some organic methods to keep pests off your precious cannabis. This includes preventative measures, by encouraging optimal plant health and resistance, using key soil amendments, and the role of beneficial insects. I will also share recipes and instructions for two organic homemade foliar sprays that we rely on. One is for the vegetative growth cycle, and one for flowering.

A variety of pests are drawn to cannabis plants. Thankfully, the cannabis pest control methods and recipes we cover in this article will help fight pretty much all of them! Our plants have been blissfully pest-free, especially since we have implemented the two sprays routinely. 

Common Cannabis Pests

The most common cannabis pests include thrips, whitefly, spider mites, leaf miners, aphids, and cabbage loopers, among others. In the ganja community, the inchworm-like looper caterpillars are also referred to as “bud worms”. If you aren’t familiar with all these insects, consider browsing this article about common garden pest identification too. Finally, powdery mildew and fungal diseases can also be an issue for cannabis. 

Our area is prone to all of these things! During our first year growing cannabis, we struggled with cabbage loopers the most. And just as I said, we didn’t realize how bad it was until too late. The caterpillars don’t just eat the buds. They also poop in them, which then creates mold.  Some of our first flowers were so full of caterpillar shit, we had no choice but to compost them. Lesson learned. Now we know how to stay on top of it, and nip the problem in the bud… before it damages our bud!

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If you don’t believe pests are much of an issue in your area, or you aren’t excited about the idea of routinely spraying your plants (even organically), then don’t. Let them go au naturale, and see what happens. This didn’t work out too well for us – but maybe your story will be different!

Cannabis Pest Prevention

The way you grow your cannabis will determine how badly pests bother it. Obviously, certain pests are more prevalent in an outdoor setting than indoors, and vice versa. For example, bud rot or mold is most common in indoor settings, with high humidity and inadequate air flow. Make sure to ventilate, circulate, and give your plants space to breathe! Furthermore, the type of soil, amendments, or fertilizers you use plays a huge role in pest prevention.  

Feed your soil to feed (and protect) your plants.

Did you know that soil quality directly influences a plants susceptibility or resistance to disease, stress, drought, and pests? By creating a healthy environment for your plants to live and grow in – full of rich organic matter, worms, and plenty of high quality compost – the stronger the plant’s immune system will be. Just like humans, and our lifestyle and food choices. We explored this concept in our introductory post on garden pest control, which applies to all types of plants – not just cannabis!  Stressed plants will get “sick” easier, and more readily attract and succumb to pest damage. The same goes for those that rely on synthetic fertilizer and chemicals for food.

Growers may add certain amendments that naturally deter pests to their cannabis soil, either as part of the initial soil mixture, or later as top-dressings. For example, neem seed meal is dual-purpose. It is an amendment that provides modest amounts of micro and macronutrients to the plant, increases soil microbial activity, and also deters pests. In general, most pests don’t like the smell of neem. It can help control unwanted nematode populations, fungi, and soil pathogens.  

Crustacean or crab meal fits the same profile and has similar benefits, particularly protecting against root knot nematodes. 

The use of aloe vera and silica in routine waterings or foliar sprays help to enhance a plants immune system and overall resilience, as we explored in the posts linked below.

If you haven’t checked them out already, you may enjoy these related articles for more information:

• How to Grow Cannabis, Organically: Seeds, Soil, Containers & Care
• Feeding Cannabis Organically: Top-Dressings, Teas, & More!
• Sexing Cannabis: How to Tell the Difference Between Young Male vs Female Cannabis Plants
• How to Wash Cannabis Flower Buds After Harvest
• How to Harvest, Dry, Trim, Cure & Store Homegrown Cannabis
• Vaporizing Cannabis: Science, Safety, Quality & Technology

The point is, when it comes to cannabis pest control – prevention and overall plant health is key! Yet even the most robust, organically grown plants will need our help to fight pests sometimes. 

Organic Pest Control Methods for Cannabis

Beneficial Insects: Use Bugs to Fight Bugs

Some insects are not desirable around our plants, while others we welcome with open arms! Many insects prey upon other pest insects. Ladybugs and lacewings are prime examples. To boost their populations, we buy and release beneficial insects in our garden. This is something I suggest for any type of garden and plants, not just for cannabis pest control.

Ladybugs

Ladybugs are ferocious predators of aphids, spider mites, mealybugs, white fly, and other soft-bodied insects. Especially in their larval form! According to the Planet Natural Research Center, a ladybug will eat up to 50 aphids a day. That means that during its lifetime, a single ladybug is capable of consuming up to 5,000 aphids!

If you are struggling with soft-bodies pest insects, consider releasing ladybugs on your plants as organic cannabis pest control! Either for an outdoor grow, or in a greenhouse setting. I probably wouldn’t recommend this if you’re growing in your closet though. Ensure you’re buying native American ladybugs and not invasive Asian lady beetles. Here is a trusted source for the right ones. 

When you release your ladybugs, here are a few tips to ensure they stick around. They have a reputation for flying off!

• When they arrive, store the ladybugs in the refrigerator until that evening. This slows down their metabolism and activity, but is totally safe.
• Release ladybugs that evening, just after the sun goes down.
• Wet the plants that you are going to place them on first.
• Ensure you release them near a food source, e.g. aphids.

Despite spraying our cannabis plants routinely with dilute neem oil (described below) we still find ladybugs all over our plants! This says a lot about just how mild neem can be. It helps deter pest insects, but doesn’t impact the beneficial ones – when done right!

Lacewings

Green lacewings provide very similar benefits as ladybugs. They feed on aphids, leafhoppers, spider mites, mealybugs, thrips and other soft bodied insects. Most often, lacewings are sold and shipped as eggs, since they can be quite fragile. The benefit of this is that eggs can’t fly off upon arrival, as some ladybugs do! Here is one source to purchase lacewing eggs. 

Like ladybugs, lacewings can be useful for cannabis pest control when released either outdoors OR in a greenhouse. We never used to see lacewings in our garden. Then, we bought a batch of lacewings eggs several years ago. Guess what? We see them all the time now!

Organic Cannabis Pest Control Foliar Spray Recipes

Before we dive into the details, it is important to note that these foliar sprays are divided into two sections – for a reason. For the most part, you want to avoid spraying your buds once they begin to develop, especially in organic gardening. Introducing extra unnecessary moisture can increase the risk of bud rot or mold. 

More importantly, any ingredients, odors, or flavors in those sprays are going to be incorporated into the flower, which you then consume in one way or another. This alone is one of the largest motivators for us to grow our own cannabis at home. It is not uncommon to find pesticide and fungicide residue in the flowers from large-scale, inorganic, commercial cannabis operations that sell to dispensaries. I don’t know about you, but I don’t want to smoke that shit. 

Therefore, we suggest to use the neem-based cannabis pest control recipe below during the vegetative growth cycle only. We have found it necessary to use another foliar spray during the flower cycle, to ward off bud worms (cabbage loopers). However, the ingredients in that spray are extremely mild, natural, and short-lived – and the only thing we personally feel comfortable treating our plants with once they’ve begun to flower. I’ll tell you more below. 

Vegetative (Pre-Flower) Foliar Spray Recipe: A Neem-Based Spray

What is neem oil?

Neem oil is a plant-based concentrated oil, extracted from primarily the seeds of the India-native neem tree. Cold-pressed extractions yield the highest quality virgin neem oil, and contain all the desirable active constituents. That is what we use! Check out a highly-recommended, cold-pressed neem here. In addition to being a natural, mild insecticide, neem also has healing medicinal properties and is commonly used in personal care products.

Neem oil is particularly effective against small soft-bodied insects. Examples include aphids, thrips, spider mites, mealybugs, and white flies – many of those so common to cannabis. However, it doesn’t seem to bother larger beneficial insects like ladybugs or bees – especially if you take care to spray it only in the evening hours, when beneficial insects are least active.  Note that neem doesn’t do much to control caterpillars.

“Neem oil is made of many components, including Omega 3, 6, and 9 Fatty Acids. Azadirachtin is the most active component as a pesticide. It reduces insects ability to feed, and acts as a general insect repellent. It also interferes with insect hormone systems, making it harder for insects to grow and lay eggs. Azadirachtin can also repel and reduce the feeding of nematodes.” 

Oregon State University

Additionally, that protective shine that neem oil adds to the leaves makes them less susceptible to fungal diseases like powdery mildew, rust, or blight. 

As moderate health-nuts and toxin-phobes, we have done quite a bit of research on neem oil. Studies show that the only risk of acute harm to mammals or humans is if they’re exposed to high concentrations of undiluted neem oil. Even with prolonged ingestion of high doses, the internal damage caused typically heals once the exposure is removed! Neem is not carcinogenic, and no chronic health effects from exposure have been found. However, neem concentrates can be toxic to fish and amphibians, so extra precaution should be taken around aquatic environments.

Ingredients 

Per one gallon of water:

• 1 tablespoons of concentrated, cold-pressed neem oil
• 1 teaspoon liquid soap OR 1 pre-wetted silica powder, described below
• Optional: 1/8 to 1/4 teaspoon aloe vera powder and/or a few drops of essential oils

Unfortunately, you can’t just mix all of these things together in your pump sprayer and go to town. Just as we all learned in elementary school science class: Oil and water don’t mix. Or at least, not easily.

Thus, it is important to fully emulsify the neem oil before adding it to the water in your sprayer. If it is not properly emulsified, it won’t mix well. The neem will come out globby and uneven on your plants. I think this is where most people go wrong with neem. Not only does this make the spray less effective, but it increases the risk of damaging the spots of the plants that get heavily dosed with undiluted neem. Strong neem can cause sunburning of leaves. 

Note that even if it is fully emulsified at the time of use, neem oil will try to re-separate from the water with time. If you make a large batch and attempt to store it, ensure to shake it thoroughly and check to see that it is still nicely mixed prior to use. We usually make a fresh batch of spray each time we need it, especially because aloe vera should be used immediately after mixing.

Emulsifying Neem Oil 

This is where the soap or silica come in to play. Both act as emulsifying agents, allowing the neem to mix with water. So, should I use silica or soap? That is a personal decision. 

We most often use silica (potassium silicate) because it provides additional benefits to the plant, such as strengthening of cell walls, leading to larger stalks and plants. It also lightly coats the leaves, making them less susceptible to fungal diseases and impacts of little leaf-sucking insects. 

Diluted liquid soap is a common DIY garden spray used against aphids and other soft-bodied insects, disrupting their cell membranes – effectively killing them when sprayed in direct contact. Our choice soap is Dr. Bronner’s Castile Peppermint soap. Insects are repelled by the peppermint odor. Therefore, while soap may not benefit the plant in the same way silica does, it has its own formidable pest-fighting attributes. 

Last but not least, we like to add aloe vera powder to all of our foliar sprays. It both feeds the cannabis, and boosts its immune system. We also add aloe to almost every cannabis watering or tea, use fresh aloe to feed seedlings and support freshly transplanted plants. To read more about the benefits of aloe vera and ways to use it as a natural fertilizer in the garden, check out this post!

Mixing Instructions 

1. If you choose to use silica powder regularly, it is easiest to pre-mix a batch of silica powder with water and store as a liquid solution. This makes it ready-to-use for your spray recipes at any time. To do so, combine 35 grams of silica powder to 8 ounces of water. Mix thoroughly, and store in a cool dark place. This will most likely last you the entire growing season.
   
2. Fill your chosen pump sprayer with just under one gallon of water – about a quart shy. Depending on how many and how large of cannabis plants you’re working with, scale up or down as needed. You’ll find your groove with time. If you want to use aloe vera powder in this foliar spray, add ⅛ to ¼ teaspoon to your gallon of water now. Cap the sprayer, and shake thoroughly. 
   
3. Next, it is time to emulsify the neem oil. In small container, such as a half-pint jar or little beaker, combine 1 tablespoon of neem oil with either 1 teaspoon of liquid soap, or 1 teaspoon of the pre-made liquid silica solution described above. Stir thoroughly to combine. This should create a creamy thick yellow liquid. 
   
4. Fill a clean quart jar about three-quarters full with warm water. Yes, it is critical to use warm water to aid in mixing, but not hot. Now pour in your neem soap/silica solution. Cap the jar, and shake the living daylights out of it. If it is fully mixed, you won’t see oil droplets forming on the surface. Your neem oil is now emulsified! (It is a tad harder to tell when using soap since it foams.)
   
5. Finally, pour the warm quart of neem solution in with the water that is already in your sprayer. Cap, and shake well to mix.

Hint: This is the same process we use for making neem oil sprays for other plants in our garden when needed.

Application & Frequency

We don’t suggest spraying neem on small seedlings, though you could use aloe or silica on them. I would wait until your plants are at least 4 to 6 weeks old, and maybe start with slightly less than one tablespoon of neem per gallon. As the plants mature, feel comfortable using the full recipe.

It is best to apply foliar sprays just after the sun goes down, for many reasons. One, beneficial insects are less likely to be present and active then. Second, this gives the spray overnight to do its work and dry a bit. Applying foliar sprays in direct sunlight can cause the leaves to sunburn.

Fully drench the cannabis plant until the leaves are dripping. Give your sprayer a shake here and there to keep things mixed. Try to spray the undersides of leaves as well. This is one reason we love putting our plants on DIY dollies with casters! We can easily move and spin them around as needed to reach all sides and angles. This is especially useful when you’re working with large 20 gallon bags and up! 

Repeat weekly or every other week for best results. We practice this routine even if we aren’t seeing obvious issues. Keep in mind, these gentle organic sprays are best as preventative measures and for mild pest problems. If you wait until a plant is overridden with pests or disease, it is much more difficult to treat organically. 

Essential Oil Additions

Just as the peppermint and neem odors are unappealing and therefore deter pests, essential oils can be used to accomplish the same thing. Essential oils are very, very concentrated – a little goes a long way! If you’d like, try adding just a few drops to the recipe above for a little extra protection. 5 drops or so per gallon of water is good.

Peppermint, lavender, orange, tea tree, or eucalyptus are some good examples of essential oils that act as natural insect repellents, though there are many others as well! We personally love this little mix-pack of certified organic EOs, for personal, home, and garden use.

Remember, we recommend this treatment during veg cycle only! Once the plant begins to flower, replace this spray with a weekly Bt-based spray, if anything. If you have aphids on your buds hereafter, I suggest hand-squashing and spraying them off with a firm blast of water. 

Stinging Nettle Tea Foliar Spray (Pre-Flower)

Do you happen to have wild stinging nettle growing in your area? This common “weed” pops up in shady and damp locations all over the U.S. during the spring time. While the sting of the nettles make it seem like a nuisance, nettles are actually loaded with nutrients and plant enzymes! We steep them in non-chlorinated water to create a natural fertilizer tea. Truth be told, the tea stinks to high hell…. and the bugs agree! Thus, stinging nettle tea can be used to feed plants – or applied as a dilute foliar spray to deter pest insects like aphids, whitefly, leaf hoppers, and more. Check out this article for detailed instructions to make and use nettle tea.

Flowering Cycle Foliar Spray for Caterpillar Control

During the flower cycle, caterpillars are a cannabis growers worst enemy. The little inchworm caterpillars hide deep inside the buds, munching and pooping away. If you do have a caterpillar issue and wait to start treating once you already have mature buds, it will probably be too late. Large dense buds are hard to penetrate with sprays, and even more so with mild organic ones. Catching them early and staying on top of your treatment schedule is key in organic cannabis pest control.

So, when exactly is a cannabis plant considered “in flower” you ask? Basically, as soon as it starts to form pistils, the earliest stages of premature buds. Pistils look like little white fat hairs, as shown in the photo above. They usually appear first at the end of branches and near the top of the plant, where the largest cola will form. Note that there is a week or two period when cannabis first begins to flower that obvious buds are not formed. Once we start to see baby buds, we start using Bt. 

What is Bt?

Bacillus thuringiensis, also known as Bt, is a naturally-occurring, soil-dwelling bacteria. It is a common active ingredient in organic biological pesticides. Namely, it kills caterpillars. It makes them stop eating. I don’t love killing things, but sometimes it is a necessary evil – and inherent part of gardening. 

“Bt is a bacterium that is not toxic to humans or other mammals, but is toxic to certain insects when ingested. It works as an insecticide by producing a crystal-shaped protein (Cry toxin) that specifically kills certain insects. Bt is naturally found on leaves and in soil worldwide and has been used commercially both in organic and conventional agriculture for over fifty years. Over two decades of review, the EPA and numerous scientific bodies have consistently found that Bt and Bt-crops are not harmful to humans.”

Entomological Society of America

Bt spray can come either pre-mixed or as a concentrate, which must be diluted before applying to your plants. Concentrates are the more cost-effective option. We use this concentrate by Safer Brand, which is OMRI-listed for organic gardening. When used on vegetable crops, Bt is considered safe for human consumption even when sprayed the same day as harvest. 

Mixing Instructions

Follow the directions on the Bt product you purchase. For the one we use, it calls to dilute 1 tablespoon of Bt per one gallon of water. Mix well directly in your pump sprayer. Unlike neem oil, there is no emulsification or warm water required. It is as simple as that!

Application

Like other foliar sprays, it is best to apply your Bt solution in the evening hours. Yet Bt is even more mild than others, and doesn’t pose the same risk for accidentally burning leaves with improper applications. On the contrary, Bt rapidly degrades in sunlight and also washes off with rain or other water. It is most effective the day or two after application, and considered virtually non existent after a week. 

I should also note that Bt is most effective against small caterpillars. It may not impact larger caterpillars, such as those over 1 inch long. With its short-lived and limited activity, it is best to spray Bt once per week if caterpillars are an issue for your plants. 

If you know me, then you know how much I love monarch caterpillars. We are very, very cautious as to not keep any milkweed near the cannabis. We also avoid over-spraying the cannabis plants onto non-target areas! I highly suggest you do the same. 

You can continue applying this cannabis pest control foliar spray up until harvest time, though we usually stop at least a few days beforehand. Don’t worry… A post explaining how to determine the best time for harvest is on the way!

And that is how we keep our cannabis virtually pest-free, organically!

Well, let me rephrase that. In a truly organic garden, there is no way to be completely pest free – nor should it be – and the same goes for our cannabis. But that is okay! Between our healthy soil, routine feedings, beneficial insects, and these foliar sprays, we are able to keep the pests to a very manageable level that doesn’t negatively impact our crops.  The one thing we have been able to ward off completely is powdery mildew! PM can be pretty damn rampant in the rest of our garden. Yet we haven’t had any issues on the cannabis, thanks to the neem and silica!

One last tip about cannabis pest control for indoor or greenhouse grows: sticky traps are your friends! While we mostly grow cannabis outdoors, we sometimes get fungus gnats and whiteflies on the seedlings or winter autoflower plants in our greenhouse. These sticky traps help grab a lot of pests for us, but don’t seem to attract ladybugs.  

I hope you found these tips informative and useful! May they help keep your nugs free of bugs.

Check out the next post in this “how to grow organic cannabis” series – all about when and how to harvest, cure, and dry your homegrown cannabis! Please feel free to ask any questions or leave feedback in the comments, and spread the organic ganja love by passing this article along to friends or pinning it below!