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indoor cannabis pest control

Pests, Bugs & Viruses

Unfortunately, bugs and other garden pests can totally mess up your marijuana harvest!

This page aims to be a comprehensive resource on the different types of bugs / pests / mold that can affect your marijuana crop, along with tips for preventing and solving each problem.

Pests that can affect your marijuana plants include aphids, fungus gnats, thrips, green flies, black flies, mosaic virus, spider mites, caterpillars, inchworms, whiteflies, white powdery mildew / white powdery mold, stem rot, and even mammals such as deer or cats!

If you want a list of safe, all-natural pesticides that can get rid of most of the pests on this list, check out this page: https://www.growweedeasy.com/safe-cannabis-pesticides

It’s time to fight back against cannabis bugs, mold and pests!

Quick Tip! Whenever you spray plants with anything, make sure to get the undersides of the leaves too, as this is where many pests like to hang out! A one-hand pressure sprayer / mister is also really helpful for spraying leaves.

Aphids
Aphids live under leaves & have different forms depending on their stage of life

Barnacles / Scale Insects
These bugs that look like barnacles and stick to the plant on stems and underneath leaves

Broad Mites
These mites are so small you will likely never see them even under a magnifier. However, you can tell your plant has been infected because your new leaves will be blistered, twisted and glossy. The overall plant will also be growing poorly and if it’s flowering the buds may turn brown. Broad mites are often mistaken for other problems like nutrient deficiencies, heat stress or pH problems.

Bud Rot or Mold
When bud rot strikes, certain buds may start looking sickly overnight, with leaves turning yellow and/or bud becoming discolored. When opened up the inside of the bud is dead or moldy.

Caterpillars, Inchworms & Cabbage Loopers
Caterpillars and worms eat holes in leaves and leave droppings that look like black specks

Crickets
“Regular” crickets will munch on your leaves while “mole crickets” can tunnel under your plants and disturb their roots!

Mole Cricket – these can tunnel under your cannabis plants like moles

Fungus Gnats
Fungus gnats look like tiny dark flies. They hang around soil that stays wet for long periods of time, and their worm-like larvae crawl around in the wet top soil. Plants start getting sick if a gnat infestation gets out of control.

Grasshoppers
You’ve probably seen these before, but these seemingly harmless garden creatures will happily eat your cannabis leaves!

Leafhoppers
These bugs come in almost every color known to man so sometimes it can be tough to tell what they are just from looking. However, they all make clusters of spots on your leaves where they’ve sucked out all the sap, so if you see spots like this you know you’ve got leafhoppers!

Leaf Miners
Leaf miners are larva that actually live inside your leaves and tunnel through them to eat!

Leaf Septoria / Yellow Leaf Spot
This fungus causes round yellow or brown spots, with symptoms often starting on lower parts of the plant

Mealybugs
These tiny white bugs look “hairy” and are found crawling on leaves and buds

Planthoppers
Each species looks quite a bit different as an adult. Some look like pretty leaves. As youngsters, they create white and fuzzy patches that look like cotton on their butts and on your plants. Planthoppers suck the life out of cannabis plants if they start a colony.

Root Rot
Root rot is a common problem in hydroponic systems though overwatered plants in containers often display similar symptoms. Plants with root rot wilt and leaves may become discolored. In the reservoir the roots turn brown, smelly and slimy.

Russet mites are so small you can only see them with a magnifier unless there are thousands of them infesting your plant. They live the the crevices of leaves, stems or buds.

Slugs / Snails
Slugs and snails usually come out at night, leaving holes in leaves with scalloped edges from their individual bite marks. They also leave slime trails on leaves and on the ground.

Spider Mites
Spider mites are often caught from another grow room, and their bites leave small white speckles all over your leaves. They’re so small they can be hard to see, though the best place to look is underneath leaves. You may see webbing if there are enough of them living on the plant.

Thrips
​ Thrips leave irregular bronze or silver marks that may look like “dried spit” or tiny snail trails. Their young look like fat, tiny worms.

Tobacco Mosaic Virus
It’s not known whether mosaic virus has jumped from tobacco to cannabis plants, but in this article I’ll share what I’ve learned so far…

Whiteflies/ White fly
Whiteflies look like tiny white moths and hang out under your cannabis leaves

White Powdery Mold
WPM leaves a white powdery substance that looks like flour or powder on leaves and stems

This easy picture guide will help you quickly diagnose your sick plants. Learn how to get rid of the most common marijuana pests!

How to Prevent Pests in Your Indoor Grow

Everyone wants a part of the growing cannabis industry, including pests. Pests are not limited to bugs, but can range from the tiniest insects to microscopic fungi and bacteria. Rest assured, your indoor grow room doesn’t have to suffer because of its popularity.

Let Kush show you how to prevent pests. We’ll walk you through how to identify and treat against some of the most common issues facing your indoor plants.

How to Detect Bugs in Your Grow Room Early

Pest infestation can be one of the biggest headaches in an indoor grow room. Early detection is key in pest control to prevent from an unfortunate outbreak.

Hanging sticky-traps can be of major benefit in the grow room for two reasons.

  1. The strips catch any flying pests
  2. They act as a good meter of how many (if any) pests are appearing in your grow room

The more insects you see stuck on a trap, the more insects are in the room, so act immediately. Flystrips, or “ribbon” strips, can be hung from the ceiling with a tack. These traps spiral down, creating a landing surface for the flying pests.

Other styles of applicators include trays and square paper. Trays can be set on any horizontal surface, such as a table or desk. Square paper can be mounted onto a vertical surface such as a wall or hung from the ceiling like the ribbon strips.

Once pests are stuck on the strips you can act immediate to prevent an outbreak. No matter which option you choose, be sure to read the instructions and warnings on the packaging.

[PRO TIP] Different insects are attracted to different colors. Select the color of your traps based on the type of insect you are trying to remove.

How to Keep Bugs Out of Your Grow Room

Is your grow room sealed? This includes door jams, windows, baseboards, and even air vents.

Pests can and will infiltrate any place they can for food. Be sure to caulk up any cracks or holes, and seal under the doors with a door sweep or other alternative bottom door seal.

Ventilation is important in the grow room for a number of reasons. A good suggestion would be to inspect the ventilation system before bringing any plants into the space. The air duct system can be set up in a number of ways, but the important thing is that it is sealed.

Duct “Mastic” is the most secure and recommended way to seal up a leaky or drafty duct, but duct tape can be used as well. The more secure the room is beforehand, the easier it will be to maintain if the need arises.

[PRO TIP] In the indoor garden the “ease of clean” factor is very important. There should not be many surfaces to scrub or intricate fixtures where pests can hide away. Milar is commonly applied to walls, ceilings, and floors for this very purpose. It is nonporous and is very easy to clean/wipe down. Remember the easier the space is to clean the easier it is to maintain.

Have You Checked Your Clones for Pests?

The most common way pests infiltrate a secure indoor garden is via clones. New clones that have been purchased from an outside source are always a concern.

Inspecting cannabis clones thoroughly before purchasing them is extremely important. Check under all the leaves, the soil, and the stalk for any stowaways. The clones should also be quarantined for at least 3-7 days before introducing them to the grow room. This allows for any delayed pests to appear.

After a week or so moving the clones into the room is okay. Continue to monitor your newly added clones for the rest of the month. If the grow room was sealed, and pests do appear after moving in new clones, then the clones (or their soil) is most likely to blame.

[PRO TIP] In addition to clean clones and soil, the clothes and equipment used in the indoor garden are also very important. Pests can latch on to anything. Shirts, gloves, boots/shoes, hats, and any other equipment being used in the grow room should be cleanedand pest free.

Some growers leave a change of clothes close to the entrance of the grow room that they can change before entering. Others perfer to use full hazmat suits. Equipment can be cleaned relatively easily before and after every session using soap and water. A spray bottle of hydrogen peroxide or rubbing alcohol can also be used. A little cleanliness goes a long way in preventing pests in your cannabis plants.

How to Prevent Pests in Your Pots & Soil

Soil should be purchased from a reputable source and should be inspected before use. A source where you can ask questions about the soil (prior to buying) is best.

The soil should be sealed, pest free, and not made from any plants or organic matter than contained pests beforehand. This includes fungus, bacteria, and fly/mite eggs.

If the soil is allowed to sit out in the sun all day, uncovered. Then flies can lay their eggs in it, so it should be avoided. Hydroponic applications are not affected by this.

All pots that are going into the grow room should be thoroughly cleaned with soap and water prior to use. This can be as simple as taking a few pots at a time outside or into the shower, scrubbing them down, rinsing them thoroughly, and drying with a clean towel. Then pot the plant as soon as this process is completed. This will substantially minimize the risk of pests.

How to Treat for Pests in Your Cannabis Grow

If pests appear then they must be treated. Pests eat organic matter. In this case it is the cannabis plants in the room that are being grown to harvest.
The added stress of pests can delay, and in some cases completely prevent, the plant from flowering. This can also turn female plants into hermaphrodite plants. This then runs the risk of pollinating the entire grow room, leaving only seed and biomass harvest as the end result.

So how to do you treat pests organically? Let’s look at a few specific situations.

Fungus Gnat

This is the most common pest in indoor grows. They do not affect the health of the plant, but can be quite annoying to the grower and the cleanliness of the grow room.

As the name suggest the fungus gnat feeds on fungus. This fungus is found in soil and composts where the gnat lay their eggs. A simple application of bt-i (or Bacillus thuringiensis var israelensis), a bacteria, on the soil, can stop fungus gnats in their tracks. This an old and natural way to treat pests, and is non harmful to fish, wildlife and humans.

[PRO TIP] Using Bacillus thuringiensis var israelensis will also stop black flies & mosquitoes in their tracks.

Aphids

Aphids are a very common pest that can be treated relatively easily.
Take the plants outdoors or into the shower. Spray your cannabis plants with short burst of water to knock off any aphids or eggs. Smash any remaining with your fingers. Then dry the plants and move them back to the grow room. Continue this for a few days until all signs of the aphids and their eggs are gone.

Spider Mites

Spider mites, and mites of all kinds, detest humidity. If the humidity in the grow room is at optimum levels for cannabis, all should be well.

On the off chance that mites do appear, simply thoroughly wash the infected plant(s) with water in the shower or outside. You can then dry the containers and place them in a location with appropriate humidity (this will be determined by which phase of growth they are in).

Spider mites can also be treated with neem oil, a rosemary based soap (most insecticidal soaps), bt-i, or ladybugs.

Caterpillars

An effective way to treat a caterpillar infestation is by bt-i. This will naturally and effectively remove the caterpillars from the plant.
Caterpillars are known for eating big sections of plant leaves. If you notice bites where the caterpillars have eaten the leaves, those sections should be removed with a sterile pair or snips to prevent possible mold growth and further infection.

Thrips

Thrips are attracted to the color blue, so blue sticky traps should be put into place to tarp as many as possible. Then if thrips remain the use of thrips predators should be implemented. These include Minute Pirate Bugs (Orius insidiosus) and Thrips Predators (Amblyseius cucumeris).

Brown Scale

Though rare, the brown scale can infect indoor gardens and grow operations. If signs of brown scale appear, fill a spray bottle with 2% rosemary based soap solution, neem oil, and water. This solution can be used to spray on the plant in the infected zones. Repeat daily until all signs are gone.

Whitefly

If you notice whiteflies in your grow, don’t be alarmed. Take the plant out to the water hose or shower and use quick burst to remove all flies and eggs from the leaves/stalks. Dry the plant and container, then place it back in the grow room. Hang yellow flystrips to catch any remaining flies.

A 2% solution of rosemary based soap, neem oil, and water can also be used, by spraying on and around the infection site. If all else fails, try predatory insects. These insects feed on whiteflies, and include: green lacewings, lady bugs, or the small wasps Encarsia Formosa.

[Note: Most treatment methods involve moving the plant for a rinse. Be sure that during the move the plant’s lighting schedule is not interrupted. This is very important for stages of growth. If the plant is receiving light, be sure to move and maintain that UV light, or move and clean in a dark space and illuminate by using a green light during inspection. The green light wavelength does not disrupt the dark cycle of the plant.]

[PRO TIP] When moving, cover plants with a black plastic trash bag to shield them from light contamination.

from the tiniest insects to microscopic fungi and bacteria. Rest assured, your indoor grow room doesn’t have to suffer because of its popularity.

Let Kush show you how to prevent pests. We’ll walk you through how to identify and treat against some of the most common issues facing your indoor plants.

How to Detect Bugs in Your Grow Room Early

Pest infestation can be one of the biggest headaches in an indoor grow room. Early detection is key in pest control to prevent from an unfortunate outbreak.

Hanging sticky-traps can be of major benefit in the grow room for two reasons.

  1. The strips catch any flying pests
  2. They act as a good meter of how many (if any) pests are appearing in your grow room

The more insects you see stuck on a trap, the more insects are in the room, so act immediately. Flystrips, or “ribbon” strips, can be hung from the ceiling with a tack. These traps spiral down, creating a landing surface for the flying pests.

Other styles of applicators include trays and square paper. Trays can be set on any horizontal surface, such as a table or desk. Square paper can be mounted onto a vertical surface such as a wall or hung from the ceiling like the ribbon strips.

Once pests are stuck on the strips you can act immediate to prevent an outbreak. No matter which option you choose, be sure to read the instructions and warnings on the packaging.

[PRO TIP] Different insects are attracted to different colors. Select the color of your traps based on the type of insect you are trying to remove.

How to Keep Bugs Out of Your Grow Room

Is your grow room sealed? This includes door jams, windows, baseboards, and even air vents.

Pests can and will infiltrate any place they can for food. Be sure to caulk up any cracks or holes, and seal under the doors with a door sweep or other alternative bottom door seal.

Ventilation is important in the grow room for a number of reasons. A good suggestion would be to inspect the ventilation system before bringing any plants into the space. The air duct system can be set up in a number of ways, but the important thing is that it is sealed.

Duct “Mastic” is the most secure and recommended way to seal up a leaky or drafty duct, but duct tape can be used as well. The more secure the room is beforehand, the easier it will be to maintain if the need arises.

[PRO TIP] In the indoor garden the “ease of clean” factor is very important. There should not be many surfaces to scrub or intricate fixtures where pests can hide away. Milar is commonly applied to walls, ceilings, and floors for this very purpose. It is nonporous and is very easy to clean/wipe down. Remember the easier the space is to clean the easier it is to maintain.

Have You Checked Your Clones for Pests?

The most common way pests infiltrate a secure indoor garden is via clones. New clones that have been purchased from an outside source are always a concern.

Inspecting cannabis clones thoroughly before purchasing them is extremely important. Check under all the leaves, the soil, and the stalk for any stowaways. The clones should also be quarantined for at least 3-7 days before introducing them to the grow room. This allows for any delayed pests to appear.

After a week or so moving the clones into the room is okay. Continue to monitor your newly added clones for the rest of the month. If the grow room was sealed, and pests do appear after moving in new clones, then the clones (or their soil) is most likely to blame.

[PRO TIP] In addition to clean clones and soil, the clothes and equipment used in the indoor garden are also very important. Pests can latch on to anything. Shirts, gloves, boots/shoes, hats, and any other equipment being used in the grow room should be cleanedand pest free.

Some growers leave a change of clothes close to the entrance of the grow room that they can change before entering. Others perfer to use full hazmat suits. Equipment can be cleaned relatively easily before and after every session using soap and water. A spray bottle of hydrogen peroxide or rubbing alcohol can also be used. A little cleanliness goes a long way in preventing pests in your cannabis plants.

Looking for step-by-step instructions on how to prevent bugs, insects and other pests in your indoor grow? Check out the tips from the experts at Kush.