How to keep bugs off weed plants: Marijuana pest control techniques

Marijuana pest control is something gardeners have had to deal with for centuries. 

Whether they are birds, insects, mammals, or even other humans, cultivated plants seem to have a target on their backs.

While humans don’t really eat raw cannabis, some pests certainly seem to like the taste. If left unchecked, an infestation can end up ruining your crop.

At the same time, using harsh chemical products to repel the pests can be harmful to you later on.

To avoid all that, we have compiled a list of some safe and effective repellents (and other safety precautions) to guide you on how to keep bugs off your weed plants.

Don’t want to read? Watch the video!

Use sterilized soil and fertilizer

The problem with unsterilized soil is that it can contain the eggs or even larvae of some common marijuana pests.

If you grow your marijuana in that soil, you will be in for a rude surprise when those eggs hatch or those larvae start to grow up.

sterilized soil cannabis
Use sterilized soil for growing

This is particularly bad for indoor growers because there are no natural predators inside your house.

It’s very easy to sterilize your own soil. The only thing you have to do is cook your soil in the oven to reach an internal temperature of around 160-180F. This will kill all molds, pests, weeds, and seeds.

Depending on the amount of soil you’re sterilizing it will take 30 to 45 minutes to reach 180F.

Do not exceed temperatures of 190F because nothing good can come of this.

Grab our complete fertilizer set to add to your sterilized soil to keep pests’ eggs at bay, and if you haven’t decided which marijuana seeds to grow, visit my seed shop now.

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Check the soil cooking tutorial by Monad on icmag.com

For large amounts of soil use 2,5 table spoon of 3% peroxide per gallon of soil. Don’t forget to use fertilizers when you’ve sterilized your soil.

Grow companion plants

Interspersing the marijuana garden with a few naturally repellent plants is certainly a good way to keep the predators away.

companion plants growing
Use companion plants while growing

Although the THC that marijuana produces acts as a natural repellent in its own right, it is often not strong enough to repel all plants (especially in the early stages of life).

Download my free Grow Bible for more tips on how to get rid of pests on your marijuana plants.

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    Particularly pungent plants like geraniums and marigolds will keep many leaf-eating insects and worms at bay.

    You can even plant some onions to ward off bigger pests like deer or rabbits.

    Here are some more companion plants your weed will love:

    Basil

    This garden favorite has a strong scent that is perfect for keeping away thrips, beetles, aphids and flies.

    Basil
    A basil plant

    Some growers even claim that it can increase oil production and flavor.

    Regardless of whether that claim is true, having some extra basil around is not a bad idea.

    Beans

    Worried about a nitrogen deficiency? Planting beans may be your remedy.

    beans
    Beans Seedlings

    When beans are growing, they absorb nitrogen from the air and deposit it as nitrites into the soil. Marijuana plants thrive on these nitrites.

    With beans around, they grow stronger and are actively protected from a slow death due to nitrogen deficiency.

    Garlic

    Garlic is a popular companion because it protects against pests and molds. It is a natural fungicide that protects marijuana plants from deadly diseases.

    garlic
    Garlic

    If not planted next to your plants, it can also be used in spray form as a spot treatment.

    Marigolds

    Marigolds are what many growers call a ‘beautiful distraction.’ When marijuana and marigolds are planted together, cannabis-loving animals opt for the marigold.

    Marigolds
    Marigolds

    It’s so strong that you could create a virtual fence of protection by planting marigolds around your plants.

    Mint

    Mint is a wonderful companion plant because of its odor. Many garden pests hate the smell of mint and avoid going near it.

    It also masks the smell of freshly blooming marijuana, keeping your grow area a bit more private. 

    Mint plant
    Mint

    Use mint with caution, however. Once planted, it tends to have a mind of its own and may overrun your garden; so, plant mint in a pot instead of in the ground.

    Peppers

    Chili peppers are a wonderful way to keep away large pests such as deer, mice, and rabbits.

    Pepper plant
    Pepper plant

    The chili pepper plant also has a root system that gives off a chemical that protects your cannabis plants from rot.

    These plants are especially useful in areas with poor drainage or excess rainfall.

    Use natural predators

    Of course, if you’re growing marijuana outdoors, you can make use of a few pest predators.

    Ladybugs are notoriously beneficial to have around your outdoor marijuana plants because they love to prey on larvae and other potential pests.

    You can buy life ladybugs at this website for around $5 per 1000.

    You should also encourage birds to nest in the area because they often like to snack on some pernicious marijuana pests.

    Put out some birdhouses or a bird feeder to get birds to come around.

    Just make sure that they stay away while the seeds are germinating because many birds do enjoy the taste of marijuana seeds.

    Use urine of pest’s enemies

    This might sound like a joke, but it actually works and it’s actually feasible.

    Many mammals like deer have a keen sense of smell and if they detect a hint of bear or puma urine, they will want to stay as far away from your marijuana plants as possible.

    Available at www.predatorpeestore.com

    Predator urine
    Predator urine to protect your marijuana plants

    That’s because they won’t want to enter territory that a much larger predator has been roaming around in.

    The same is true for rabbits and fox urine. You can buy these scents at many sporting goods or outdoor shops.

    Build a fence

    If bigger animals are a problem and the scent of their enemies doesn’t deter them, then you might need to try building a fence around your plants.

    fence around plants
    Build a fence around your plants for protection

    Obviously, many marijuana growers don’t have this luxury and it’s really only something that people growing on private land can do. 

    Here’s a link with tips on how to build your fence to protect your marijuana.

    Create a repellent force field

    With a permethrin-based repellent, you can keep insects away from your plants without using the synthetic spray on the plants themselves.

    Simply spray a ring on the ground about 6 feet away from the plant. Any bugs that come into contact with the permethrin will die or just evacuate the area.

    permethrin repellent
    Permethrin-based repellent to protect your weed

    Sawyer: “For use on clothing, tents, and other gear, Sawyer Permethrin not only repels insects, they actually kill ticks, mosquitoes, chiggers, mites, and more than 55 other kinds of insects.”  

    Sounds great right? You can also spray it around your plants, available at www.sawyer.com

    There are also many organic repellants that you can create at home. Here’s one of my favorites:

    Oil Spray is a mixture of vegetable oil and soap, while soap spray is a soap and water solution.

    Both are basic insecticides, killing insects such as aphids, mites, beetles, and thrips.

    Other natural ingredients, such as neem oil, garlic, and chili powder can be added to the oil or soap sprays to increase effectiveness. For best results, spray plants at dusk or dawn.

    Other natural solutions include dusting the ground with diatomaceous earth, combining various insecticides into a single spray, and creating a spray out of tomato leaves. Here are some more recipes:

    Oil-Based Insecticide

    Oil spray insecticide can easily be made from mild soap (Castile works great) and vegetable oil.

    Oil-Based Insecticide
    Oil-Based Insecticide

    This simple, yet effective spray will kill insects such as aphids, thrips, and mites by suffocation. The solution blocks their pores.

    To create your own solution, mix 1 cup of oil with 1 Tbl of soap. Mix it up well then dilute 2 teaspoons of it in 1 quart of water.

    Soap-Based Insecticide

    Soap spray insecticide is similar to oil spray, except it doesn’t have the vegetable oil.

    It also kills insects but is particularly useful for whiteflies, mites, and beetles.

    Soap-Based Insecticide
    Soap-Based Insecticide

    Soap spray and oil spray can be used at any time, but are best applied near dawn or dusk.

    To make a soap-based insecticide mix 1 ½ tsp of mild soap with a quart of water. Spray it directly on our plants.

    Neem Oil Insecticide

    The Neem Tree has a natural defense system in the form of oil that makes it difficult for insects to survive.

    It is a hormone disrupter that keeps insect predators away. Neem Tree oil is safe for everything except insects and is also a power fungicide.

    Neem Oil Insecticide
    Neem Oil Insecticide

    Use Neem oil insecticide to drive away and prevent insects, as well as fight powdery mildew and other fungal infections.

    Neem oil insecticide is available at most garden stores. You can also create your own mixture by combining 1 tsp of liquid soap with 2 tsp of neem oil in 1 quart of water.

    Garlic-Based Insecticide

    Although garlic may actually be an insect repellant rather than an insecticide, it is still quite effective.

    Garlic is ideal for at least slowing down an insect infestation. Spray as needed on infested plants.

    Use garlic-based insecticide
    Garlic can be used in a spray insecticide

    Ladybugs are good for your plants because they prey on larvae and other potential pests. 

    To make a garlic spray insecticide puree two bulbs (not cloves) of garlic in a blender with a little water.

    Leave it overnight, strain, and add ½ cup of vegetable oil, 1 tsp of mild soap and enough water to fill a quart. Mix 1 cup of this mixture with another quart of water. Spray as needed.

    Chili-based Insecticide

    Like garlic, chili pepper may be more insect repellent than anything else.

    Use it in your garden, but remember to wear gloves and protect your eyes, nose, and mouth. The spray won’t harm you, but it might hurt.

    Chili-based Insecticide
    Use chili as an insect repellent

    Create homemade chili spray out of fresh chili peppers, or use chili powder.

    If using powder, mix 1 Tbl of the powder with a few drops of liquid soap and 1 quart of water.

    From fresh peppers, puree ½ cup of peppers in a cup of water, add a quart of water and bring to a boil.

    Let the mixture cool, strain out the peppers and add a few drops of soap to the liquid.

    Your homemade spray is safe to spray directly on your plants.

    Diatomaceous Earth

    Fossilized algae buried deep in our earth is a natural resource that also makes a wonderful insecticide.

    Unlike other materials, diatomaceous earth does not poison or suffocate insects. It does something entirely different – it dehydrates them.

    Diatomaceous Earth
    Diatomaceous Earth

    Diatomaceous earth is easy to find in most garden stores, but it’s generally sold in bulk.

    You won’t need much to get the job done. To use it, simply dust the area around your plants and on the plants as well. It will keep away insects, as well as snails and slugs.

    Don’t forget to reapply after it rains.

    All-in-one insecticide

    Sometimes, a mixture of a few natural remedies makes the best spray.

    To create an all-in-one insecticide, puree 1 garlic bulb, a small onion and a teaspoon of cayenne pepper powder.

    All-in-one insecticide - garlic, onion, and cayenne peppers
    All-in-one insecticide

    Let the mixture sit – ideally for an hour. Strain the material and add 1 Tbl of liquid soap.

    Do not dilute. Spray on the upper- and undersides of leaves.  Store in the refrigerator for up to a week.

    Tomato Leaf Insecticide
    Tomato leaf insecticide

    Tomato leaf insecticide

    Although hardly tried-and-true, tomato leaves may actually be a natural insecticide.

    As a member of the nightshade family, they contain alkaloids that keep aphids (and other insects) at bay.

    To make tomato leaf insecticide, steep 2 fresh tomato leaves in a quart of water overnight.

    Strain the material and spray the liquid directly on your plants’ leaves.

    Animal/pest control for marijuana plants

    Castor oil

    Castor oil is used to repel moles and gophers. Both are underground rodents clearing tunnels to their dens.

    Castor oil
    Castor oil

    Moles are bug eaters and will not harm your marijuana plants; they will divert the direction of their tunneling to circumvent the root systems.

    Gophers, on the other hand, will chew right through the roots, damaging the plants’ source of water and nutrient uptake.

    Gophers are repulsed by the taste and smell of castor oil.

    By soaking a piece of paper in castor oil and dropping it down the entrance to the burrow, these destructive critters will find a new location to build their ‘town’.

    Another option is a relatively new product in the form of granules. It consists of castor oil, soap and corn cob granules.

    Simply spread the granules, according to package directions, on the known areas and either water in or let Mother Nature do the work for you.

    The granules soak into the soil, releasing the repugnant smell both moles and gophers hate.

    This treatment is completely natural and actually benefits the soil or lawn. 

    Check your local garden center for granulated products. Castor oil in its raw form can be found at any drug store or supermarket.

    Cholecalciferol (vitamin D3)

    This is a rodent killer (rats and mice) that doesn’t kill them immediately, rather they die a slow death, taking three to four days for the poison to work its deed.

    Cholecalciferol Vitamin D3
    Cholecalciferol

    Cholecalciferol introduces massive amounts of calcium into the rodents’ system, causing crystallization in their bloodstream, kidneys, stomach and lungs, eventually leading to heart failure.

    This treatment is toxic to household pets and humans, although the toxicity levels are lower than other available rat poisons.

    Quintox and Campaign are brand names under which the product is sold.

    Fumigants

    Fumigants are a last resort in gopher and/or mole control. (Remember, moles pose no threat to your cannabis garden, as they eat bugs, not plants).

    Fumigants
    Fumigant

    Fumigants come in the form of cartridges loaded with charcoal, sodium nitrate or sulfur and are placed in the burrow once the fuse is lit.

    This dispels toxic fumes into the tunnel.

    However, fumigants are the least reliable form of exterminating gophers due to the complexity and ever-winding path of the towns they build leading to their actual dens.

    Dens can be several feet below ground.

    Predator urine

    Predator urine is used to keep deer from trampling upon and eating your marijuana plants. 

    Deer chief predators are coyotes, mountain lions, wolves and wild dogs.

    Predator Urine
    Predator Urine

    The concept of predator urine as a deterrent follows the natural course of the food chain. Animals mark their territory with urine.

    When a deer smells the pee of a foe, it’ll stay away.

    Rather than apply the urine to Mary Jane, create a barrier by spreading it around perimeter plants or by applying it to strips of cloth attached to rope or cord around the garden.

    Place the treated strips about three feet apart along the entire length. Predator urine is available online.

    Putrescent eggs

    Rotten eggs are another effective deterrent for deer.

    Egg repellants are available commercially or you can make your own organic deer-be-gone at home.

    Rotten eggs
    Rotten eggs

    Blend together four to six eggs, four hot peppers, six cloves of garlic and five cups of water.

    Set the mixture in the sun for a couple of days to ferment and become rancid.

    Strain through cheesecloth and add to a spray bottle. This mixture can then be sprayed around the plant area. Repeat after rains.

    Zinc phosphide

    Zinc Phosphide is a fast acting rat poison. However, recent information released in April 2012 warns of the extreme toxic danger to humans and pets.

    Rat poison
    Rat poison

    It is not recommended to use this as rodent control for that reason. You certainly wouldn’t want this poison anywhere near Mary Jane!

    Use custom organic repellents

    Many growers have opted for pungent, organic repellents to keep pests away from both their indoor and outdoor plants.

    Concoctions like cinnamon oil, clove oil, and coriander oil have all had relative success without causing any damage to the plant.

    You can easily spray these repellents directly onto the cannabis leaves with no fear of any adverse reaction.

    Need seeds to grow healthy marijuana plants? Visit my online seed bank today!

    cannabis seeds

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    Of course, different cannabis strains might have different reactions to any homemade organic repellents, and you should always test the repellents on an inconspicuous section of the plant to make sure no harm is done.

    We have actually developed a natural and organic product that protects your marijuana plants from all common pests and bugs.

    It is like a pesticide for marijuana plants, called the Marijuana Plant Protector System. Quickly have a look here: Bergman’s Plant Protector

    Marijuana Plant Protector Set

    Although it might not seem like it, it is actually more difficult to control pests indoors than it is outdoors.

    There’s really a small window of vulnerability between germination and seedling state when you have the plants outdoors.

    When they’re indoors, however, the pests can ravage your entire garden up until late in the vegetative state.

    Once you have bugs in the house, it’s hard to get them away from your marijuana plants.

    It’s always best to try using preventative measures so that bugs never become a problem in your indoor garden.

    Here’s a list with all pests on marijuana plants and how to treat them.

    Also read “Cannabis pests & bugs – Control and identification

    A solution like a Pot for Pot‘s windowsill grow keeps your grow nice and orderly as well. Be sure to check them out.

    We ship seeds only to the USA. For any growing-related questions please visit the marijuana support forum.

    Want to know when your plants are ready for harvest? Grab my free mini harvesting guide.

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      FAQ about How to keep bugs off weed plants

      What are some examples of homemade bug spray for weed plants?

      There are several types of homemade pesticides for weed plants. You can use neem oil insecticide, soap-based insecticide, garlic-based insecticide, vegetable-oil-based insecticide, and chili-based insecticide, to mention a few.

      How to keep bugs off plants without pesticides?

      Some pesticide-free methods include growing companion plants and using sterilized soil and fertilizer. You can also make use of natural predators, the urine of the pest’s enemies, or even build a fence.

      What bugs are good for weed plants?

      Ladybugs are good for your plants because they prey on larvae and other potential pests. 

      Happy growing!

      Robert

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      Avatar for Robert Bergman

      Robert Bergman

      Robert Bergman is an Amsterdam-based marijuana grow expert who has years of experience from small grows to massive operations. His passion for growing led him to develop his own Gold Leaf strain. Now, Robert is dedicated to sharing his knowledge with the world.... [Read full bio]

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