All-Natural Pesticides – Safe Up to Harvest!
Got bugs on your cannabis plants? A pest infestation can be a grower’s worst nightmare, but luckily there are ways to get rid of bugs without harming your plants or affecting your buds. This list of all-natural remedies will get rid of many different types of bugs without harmful chemicals, and some of these pesticides are even organic!
These pest remedies can be used up until the day before harvest!
I know, I know, this seems really basic, but the best way to prevent an infestation is to either prevent it altogether or catch it as soon as possible. Even if you can completely get rid of a pest, it’s better to not have them be living, breeding, and making waste on your plants. Here are a few tips to help keep your grow area a bug-free zone:
- Check leaves at least weekly for signs of stress or bug bites. If possible, it’s much better to do a quick check every day. Check underneath the leaves and all over the plant. Make sure none of your buds are becoming discolored.
- Don’t go straight from outdoors to your grow room. You may accidentally track in bugs from your garden. Even healthy-looking plants near your house can be hiding a secret army of aphids or spider mites. Just be careful what goes in the grow room!
- Even if you trust the grower, treat new clones with a wide-spectrum but natural pesticide like the ones listed below just in case the clone is infected (this is one of the most common ways growers get bugs in their grow!). Even 2 or 3 eggs on your clone is all it takes to start a new infestation! Some growers might not even realize they have bugs so it’s up to you to make sure they don’t get in the grow room!
Table of Contents
Safe, All-Natural Pesticides
Remove or Spray Off as Many Bugs as Possible
I know this might seem obvious to some people, but I didn’t really think about this until someone told me!
If your plant is heavily infested, it’s a good idea to try to cut down their numbers in every way possible even before you treat them with something. Depending on the infestation, one way to do that may be to simply move your plants outside and spray as many bugs off as you can with a sprayer.
It’s also a good idea to remove leaves and buds that are heavily infected, especially if you see lots of eggs under the leaves. If you have some sort of fungus or mold, carefully remove the infected areas without touching any healthy plant tissue.
If possible, spray off as many bugs as you can, and remove heavily infected leaves. Whatever treatment you follow up with will now be more effective!
Neem Oil is safe, organic and effective at many bugs as well as molds and fungus. Generally, I’ve found that when you mix it with water as directed, it doesn’t have a crazy strong smell (reminds me of garlic and sort of earthy) and the smell doesn’t stick around for long. As far as safety, you can use this product up until the day before harvest. But, as with any pesticide, always try to avoid letting any get on your buds because it may end up affecting their final taste/smell if it doesn’t have enough time to dissipate first before harvest. If your plants are infested with bugs bad enough that the buds themselves need to be treated, it’s often time to harvest anyway!
That being said, Neem oil is an all-natural remedy that is very effective against many different types of bad bugs and mold, but won’t hurt humans, animals or most “good” bugs like bees, ladybugs, predatory wasps, etc. You will need a mister (also called a “One-Hand Pressure Sprayer”) to spray all the leaves evenly since neem oil and water can separate easily.
Use right before the lights go out (or the sun goes down) so it doesn’t burn your leaves.
Important note about Neem Oil:
Neem Oil is one of the most widely used, and most effective ways of combating pests in the grow room. When we surveyed our readers, it’s used by growers 8 times more than the next most popular pesticide, natural or not.
With that being said, there are people who have reported adverse reactions to buds grown using Neem Oil as well as Neem Oil itself. Additionally, some people can be allergic to Neem Oil, which can become a real problem when they smoke buds grown with Neem. Make sure you’re using Neem Oil safely by following a few simple guidelines:
- Don’t use Neem Oil if you’re growing weed for someone other than yourself.
- Don’t use Neem Oil if you’re growing weed for a medical patient.
- Although this might seem obvious, don’t use Neem Oil if you’re allergic to it.
- If you’re not sure, try a different pesticide that doesn’t contain Neem Oil, like Plant Therapy.
Fatty acid salts or insecticidal soaps weaken the outer shell of bugs but are safe for humans and don’t leave much of a residue.
With soaps, coverage is very important as it does not stay on your plant for long, so follow-up applications may be necessary. Although this is considered safe, avoid getting any on your buds so it doesn’t affect the taste/smell!
Spinosad Products are organic and completely harmless to pets, children, and plants. You can apply Spinosad products directly to kill bugs on contact and it should be sprayed liberally anywhere you see bugs and especially under the leaves. Although maybe not as strong against pests as some of the harsher insecticides, it does work and it’s very safe for plants, animals, and humans!
Spinosad is an organic insecticide made from the fermentation of a specific soil bacteria (actinomycete Saccharopolyspora spinosa) and kills bugs via ingestion or contact by affecting the insect’s nervous system. Spinosad can be a good choice for organic and outdoor growers, because it is very toxic to many pests, but is less toxic to many beneficial insects and spiders.
Most spinosad products are effective for only about 24 hours after being mixed with water, so only mix as much as you will need per application. Anything left over will be wasted.
You will need a mister (also called a “One-Hand Pressure Sprayer”) to cover all the leaves evenly when spraying them with spinosad products.
Spinosad and Honeybees: Spinosad is super toxic to pests and less toxic to beneficial insects. However, it can still be toxic to honey bees if they come into contact with it within 3 hours of spraying. After about 3 hours, the Spinosad dries and any bees are safe (even with residue). You can use Spinosad and not harm a single bee by following two rules:
- Only use Spinosad for indoor grows. If you’re an indoor grower, this should be pretty easy.
- If you’re an outdoor grower, only spray at night. Bees are only active during the day, so if you spray at night the Spinosad will have time to dry and your bee neighbors can go on pollinating the following morning!
Many plants have evolved their own defenses to keep bugs from eating them. Horticultural oils harness the power of these plants by refining their oils and using them to go on the offense against pests. In fact, many natural pesticides use the oils of various plants as their main ingredients. Another bonus of horticultural oils is that they don’t leave a film on your plants. However, this means they don’t last a very long time (around 8 hours), so you will want to either apply daily or combine with other options. You will need a mister to apply these treatments.
Examples of Pesticides with Horticultural Oils:
- Lost Coast’s Plant Therapy (Contains multiple things on this list: horticultural oils, soap, alcohol. Combo!)
- Essentria IC3
- Peppermint Oil (Use heavily diluted with water; the above options both contain peppermint oil)
Caterpillar “BT” Spray (safe biological insecticide)
This biological insecticide contains the bacillus thuringiensis (BT) bacteria which kills larva and prevents caterpillars from being able to eat. Make sure to get something labeled for caterpillars, as there is a different type of BT that’s good for killing mosquitos but isn’t as effective on caterpillars.
It doesn’t work against every type of bug, but this is one of the most effective ways to kill caterpillars and won’t hurt most beneficial insects. As a bonus, it can also kill some other cannabis pests like worms and moths.
If you see caterpillar damage, try a “BT” spray. It’s very safe and makes it so caterpillars can’t eat.
Apply a caterpillar BT spray as soon as you see leaf damage, caterpillars or caterpillar poop. BT sprays work best on small caterpillars that are actively eating your leaves. Repeat every week for as long as you’re still seeing caterpillars, though you can give BT more often if there’s a heavy infestation. Make sure to thoroughly mist both the tops and bottoms of leaves and apply again after a heavy rain (since that will wash the BT away).
Or save some money in the long run by getting the concentrated version with a mister
Since BT is harmless to humans, you can use BT products up to the day of harvest! One thing to keep in mind is BT spray almost instantly stops caterpillars from being able to eat, but doesn’t kill them directly. So, although you may see the caterpillars alive and apparently unharmed after spraying, the BT is still doing its dirty work because they’re slowly starving to death.
Alcohol & Water
Make a solution of 9 parts water to 1 part rubbing alcohol and spray plant once a week until bugs are gone. With an alcohol-water mixture, the goal is to spray the bugs directly to kill them. Since all the alcohol will evaporate into the air within minutes, it won’t give your plant a protective “coating” like soaps or oils.
This will likely not cure an infestation, but it’s very effective at bringing numbers down quickly!
Most effective against:
Diatomaceous Earth is basically fossil dust which you sprinkle on the top of your soil, and anywhere else in your room (window sills, doorways, etc.). This powder-like substance is harmless to mammals and plants but is incredibly sharp at the microscopic level. Therefore, it will tear and dehydrate bugs on physical contact. This will not get rid of an infestation, but can help prevent, control and slow things down when used effectively!
- Almost every type of bug is at least deterred, and it’s particularly effective against smaller soft-bodies insects and larva (including Fungus Gnats)
Floating Row Covers – Physical Barrier
These may not be the best choice for all cannabis growers, but these are very cheap and effective against many types of hard-to-stop bugs because it physically prevents them from getting to your plants, while still letting light into your plants. You can also water your plants through the netting. These are sometimes used to make mini “greenhouses” on the plants, or some growers will just drape them over the plant as they’re so light and airy they don’t really bother the plant.
These are much easier to use and are more effective with smaller plants, as it becomes difficult to fully cover larger plants. However, for young plants, these can be great! They also protect your plant from wind and some harsh conditions.
Floating row covers look like thin netting or mesh and provide a physical barrier against pests
Traps – Physically Capture Bugs
There are certain types of traps that physically capture bugs instead of kill them.
- Crickets – Cricket bait & Cricket traps
- Fungus gnats – Yellow sticky cards
- Slugs & snails – Beer trap: mix flour with some stale beer and use it to fill a shallow container. Place in garden with the rim 1 or 2 cm above the ground so that slugs and snails can climb in. Substitute beer for wine, sugar water, juice, or water mixed with yeast. BE WARNED, the trap will fill up quickly so come back often to empty.
Beneficial insects may eat large numbers of bugs and are welcome guests in the garden. Many of these can be ordered online so you can release thousands into your garden at once. These natural enemies may not be enough wipe out pests, but can definitely help cut down on an infestation!
Add These “Good” Insects for the Garden
- Mealy bugs
- Moth eggs
- Spider mites
The Best Option: Prevention
This subject has already been brought up, but I have to do it one more time!
There are many cases where a grower gets bugs through no fault of his or her own. You can take every precaution and still end up with pests infesting your grow room. There is no amount of diligence that can completely stop pests from getting into grow rooms; their lives depend on eating your plants!
However, a good helping of prevention can stop most pest infestations. If you stick to a few guidelines, you can dramatically reduce the number of pests that end up getting into your grow room. In fact, we’ve spoken to many growers who have grown for years and have yet to deal with a significant pest problem. Let’s go through a few ways you can make sure bugs never get the opportunity to live with your cannabis plants!
Fan blowing over the plants and top of growing medium
Believe it or not, air circulation is one of the best ways to let pests know they’re not welcome. Pesticides are great at exterminating pests that get in the front door and settle down, but a fan makes it so they don’t even get the chance. Many pests – like fungus gnats and spider mites – need to land on plants and have them be still so they can mate and lay eggs. A fan makes it so the environment is too windy for them to successfully multiply. Many types of bugs don’t like the breeze and can’t mate in windy conditions. Some bugs need wet topsoil to survive which can be prevented with a windy environment and good watering practices. When choosing an outdoor spot to grow, it’s a good idea to pick a breezy spot if possible.
Warning: Avoid using a fan if only a single plant has been infected by bugs or if you suspect you have active mold. If the problem is still localized, a fan can spread spores or bugs/eggs to your other plants. Before turning on a fan, remove the plant or at least all the affected parts first.
If you’ve got one of the problems listed here, a strong breeze blowing over the plant can help! Fans are best at prevention, though they can still be a good tool in your arsenal after the plant has already been infected.
Avoid going directly into your grow room from outside
White Powdery Mildew, Fungus Gnats, Aphids, Moths, Whiteflies, and Spider Mites are just a few pests that you can accidentally track into your grow room from outside. Just as a test, if you have any plants outside, do a quick check to see what bugs you can find. Even the most cared-for gardens and lawns will turn up with something. Roses are great carriers for spider mites and especially aphids, and I’ve had a bougainvillea bush that was a moth factory! Even if your outside garden has pests, you can keep them out of your indoor garden by just changing clothes before seeing your weed plants. You can even just stop in a place other than your indoor garden for a few minutes so that any pests will hopefully be left in a place where they can’t do any damage.
Get a list of all the pesticides that are safe to use on cannabis plants up until the day of harvest. Learn which bugs each one works for!
Organic Cannabis Pest Control: How to Keep Bugs Off Your Nugs
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!
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!
- 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 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!
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
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.”
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.
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 in the garden, check out this post!
- 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.
- 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.
- 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.
- 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.)
- 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.”
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.
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!
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!
Come discover organic cannabis pest control methods, including preventative measures, soil amendments, beneficial insects, and recipes for foliar sprays.