A Guide to Dealing with Spider Mites on Cannabis Plants

It’s a familiar situation for many cannabis growers – you glance over at your prized plants, and notice something concerning. There are tiny,web-like threads covering the leaves and the buds. What could it be? Unfortunately, it’s all too common for spider mites to infest cannabis plants, causing damage and ruining your harvest. These pesky pests can be difficult to detect and even harder to get rid of, but with the right knowledge, tools, and treatment methods, you can save your crop. In this article, we’ll go over everything you need to know to recognize and treat spider mites on cannabis plants, from their physical characteristics to prevention and treatment methods.

What are Spider Mites?


What Are Spider Mites?
As a cannabis grower, encountering pests can be a perplexing and frustrating experience. One pest that is particularly harmful to cannabis plants is the spider mite. These tiny arachnids are difficult to spot with the naked eye, but their damage can quickly become noticeable. Understanding the physical characteristics and types of spider mites that can infest your cannabis plants, as well as the symptoms of an infestation, is key to preventing and treating them effectively.

Physical Characteristics

Spider mites are tiny pests that are difficult to see with the naked eye. They measure only about 1/20 of an inch in length and have an oval-shaped body. They have eight legs and differ from insects, which have six legs. Spider mites have piercing-sucking mouthparts that they use to feed on the sap of plants, including cannabis plants.

There are several physical characteristics that can help identify spider mites on cannabis plants. Here are some of them:

  • Webbing: Spider mites create fine webbing on the undersides of leaves, which is a sure sign of an infestation.
  • Color: Depending on the species, spider mites can be red, brown, yellow, green or black. They may also have spots or stripes.
  • Damage: Spider mites cause damage to plants by feeding on the sap, causing yellowing or browning of leaves, wilting, and stunting of growth.
  • Movement: Spider mites are very active and move quickly across the leaves of a cannabis plant. They can also be seen using a magnifying glass or microscope.

Identifying spider mites early on is crucial to preventing a full-blown infestation. Check plants daily for signs of webbing, discoloration or damage, and inspect them closely with a magnifier if necessary. By being vigilant and taking preventative measures, you can keep your cannabis plants spider mite-free and healthy.

Types of Spider Mites

Spider mites are tiny arachnids that belong to the Tetranychidae family. There are many different types of spider mites that can harm cannabis plants, including Tetranychus urticae (two-spotted spider mite), Panonychus ulmi (European red mite), and Eotetranychus carpini borealis (spruce spider mite).

One of the most common spider mites found on cannabis plants is the two-spotted spider mite. These spider mites have a pale green or yellow color and two dark spots on their backs. They are typically found on the underside of leaves and can quickly reproduce and spread to other areas of the plant.

The European red mite is another type of spider mite that can damage cannabis plants. These spider mites have a reddish-brown color and have fine hairs on their bodies. They also tend to congregate on the stems and leaves of cannabis plants.

The spruce spider mite is another type of spider mite that can cause damage to cannabis plants. These mites are smaller than the two-spotted spider mite and have a dark green or black color. They can be found on the branches and needles of spruce trees or other evergreens, but may also infest cannabis plants.

It is important for cannabis growers to be aware of the different types of spider mites that can infest their plants, as each type may require a different approach to treatment. By identifying the specific type of spider mite that is causing the infestation, growers can choose the most effective treatment method to eliminate the pests and protect their cannabis crops.

Symptoms of Spider Mite Infestation on Cannabis Plants

Spider mites are tiny arachnids that are known to infest cannabis plants. It’s important to know the symptoms of spider mite infestation so that you can take action quickly to prevent further damage to your plants. Here are some of the key indicators that your cannabis plants have been infested by spider mites:

Symptom Description
Yellowing Leaves One of the most common signs of spider mite infestation is the yellowing of leaves, particularly on lower branches. This is due to mites sucking away at the chlorophyll in the leaves.
Fine Webbing Spider mites spin webs that can be seen on the surface of leaves and between branches. This webbing often looks like fine white strings and can easily be noticed under bright light.
Leaf Spots As spider mites continue to feed on plant sap, they leave behind small yellow or brown spots on infected leaves.
Stunted Growth A spider mite infestation can slow down the growth of cannabis plants, particularly if it is left untreated for too long.
Visible Mites If the infestation has reached a particularly advanced stage, it may be possible to see the spider mites themselves crawling across the surface of leaves.

If you notice any of these symptoms on your cannabis plants, it’s important to take immediate action to prevent further damage.

Prevention Methods

Prevention Methods
As the saying goes, prevention is better than cure. This principle applies to spider mite infestations on cannabis plants too. It is easier to prevent spider mites from attacking your plants than to treat them after infestation. Taking preemptive measures can save you time, effort, and money in the long run. In this section, we will discuss some effective prevention methods that can keep spider mites at bay and promote the healthy growth of your cannabis plants.

Keeping Cannabis Plants Healthy

Keeping Cannabis Plants Healthy

Maintaining healthy cannabis plants is the foundation of preventing spider mite infestations. Here are some steps to take:

  • Start with healthy plants: Purchase cannabis plants from a reputable source or start with seeds from a trustworthy seed bank to ensure they are disease-free and healthy.
  • Use proper growing techniques: Ensure that the grow room is set up correctly with proper lighting, temperature, humidity, and ventilation. Provide adequate water and nutrients to the plants.
  • Monitor plants closely: Check plants daily for signs of stress or disease. Early detection can prevent a small issue from becoming a big problem.
  • Prune plants: Remove any dead or yellowing leaves to help prevent the spread of diseases.
  • Maintain cleanliness: Remove any debris or dead plant matter from the grow room to prevent a buildup of hiding places for spider mites or other pests.

By taking these steps to maintain healthy cannabis plants, you can lower the possibility of having a spider mite infestation.

Cleaning and Disinfecting Grow Room

One of the most effective ways to prevent spider mites from infesting your cannabis plants is by keeping your grow room clean and disinfected. By doing so, you can eliminate any potential breeding grounds for these pests and reduce the risk of an infestation. In order to properly clean and disinfect your grow room, there are several steps that you will need to follow:

Step Description
Step 1 Remove all plants and debris from the grow room. This includes any dead leaves, branches, or other plant material that may be present.
Step 2 Thoroughly clean and disinfect all surfaces in the grow room. This includes walls, floors, ceilings, shelves, and any other surfaces that may be present. Use a solution of bleach and water to disinfect these surfaces. Be sure to wear gloves and eye protection when working with bleach.
Step 3 Clean and disinfect all equipment that may have come into contact with spider mites. This includes pots, trays, tools, and any other equipment that may have been used in the growth or care of cannabis plants. Use a solution of bleach and water or hydrogen peroxide to disinfect these items.
Step 4 Allow the grow room to dry completely before reintroducing any plants or equipment. This will help to prevent any residual moisture from creating a favorable environment for spider mites to thrive.

By following these steps on a regular basis, you can help to prevent spider mites from infesting your cannabis plants and ensure that your grow room remains clean and healthy. In addition to cleaning and disinfecting your grow room, there are other prevention methods that can be effective, such as keeping your plants healthy, avoiding cross contamination, and introducing predatory insects.

Avoiding Cross Contamination

One of the key ways to prevent spider mite infestations in your cannabis plants is to avoid cross-contamination, which means preventing the spread of the pest from one plant to another. Cross-contamination can occur when you touch a plant that is infested with spider mites and then touch a healthy plant, transferring the pests from one plant to another. To avoid cross-contamination, you should:

  • Quarantine new plants: Always keep new plants separate from your existing cannabis plants for at least one week to ensure that they do not bring in spider mites or other pests. Keep the new plants in a different room or area, and monitor them carefully for any signs of an infestation before introducing them to the rest of your plants.
  • Wash your hands: Before touching or working on your plants, make sure to wash your hands thoroughly with soap and warm water. This will remove any spider mites, their eggs, or any other pests that may be on your hands.
  • Wear dedicated clothes: When working with your cannabis plants, wear dedicated clothes that you don’t wear outside or in other areas of your home. This will prevent you from accidentally carrying spider mites or other pests on your clothing.
  • Use dedicated equipment: Avoid using the same gardening tools or equipment on different plants, especially if some of them are infested with spider mites. Instead, use dedicated equipment for each plant or set of plants, and clean the equipment thoroughly between uses.
  • Control the environment: Spider mites thrive in hot, dry environments, so it’s important to keep the temperature and humidity levels in your grow room within the optimal range for your plants, but not so high that spider mites can thrive.

By implementing these measures, you can significantly reduce the risk of spider mites infesting your cannabis plants, keeping them healthy and free of pests.

Introducing Predatory Insects

One effective method for controlling spider mites on cannabis plants is by introducing predatory insects into the grow room. These insects can help to reduce the population of spider mites and prevent future infestations. Here are some predatory insects that are commonly used in cannabis cultivation:

  • Phytoseiulus Persimilis: These tiny mites feed exclusively on spider mites and are highly effective at controlling them. They are best used in lower temperatures and humidity.
  • Amblyseius Andersoni: These mites are effective at controlling spider mites in a wider range of temperatures and humidity levels. They also feed on other pests, making them a versatile option.
  • Neoseiulus Californicus: Similar to Amblyseius Andersoni, these mites are effective at controlling spider mites and other pests in a wider range of conditions.
  • Ladybugs: Ladybugs are a popular choice for controlling a variety of pests, including spider mites. They are highly effective and relatively easy to find, making them a convenient option for many growers.

When introducing predatory insects into the grow room, it’s important to follow the instructions carefully to ensure maximum effectiveness. Some common tips include releasing the insects at night when the lights are off and providing them with a food source (such as pollen) to help them thrive.

While introducing predatory insects can be an effective method for controlling spider mites on cannabis plants, it’s important to note that it may not be sufficient for severe infestations. It’s always a good idea to use multiple methods for controlling spider mites and to monitor the plants closely for any signs of pests.

Treatment Methods

After identifying the presence of spider mites on your cannabis plants, it is crucial to take action to prevent further damage to your crop. This section will outline various treatment methods to help eliminate these pesky pests and prevent their return. From organic solutions to chemical options, there are multiple approaches to consider when dealing with a spider mite infestation. Let’s dive into the possible treatment methods that can help redeem your plant’s health and vitality.

Identifying Spider Mites

Identifying Spider Mites on your cannabis plants is crucial in treating and preventing an infestation. Here are some key features to look for when identifying spider mites:

Physical Characteristics: Spider mites are very small, less than 1/50th inch long, so they can be difficult to spot with the naked eye. They are typically red, brown, or yellow in color and have eight legs.
Mite Damage: Upon close inspection, you may notice webbing on your plants or the leaves may appear speckled or discolored. Infestations typically start on the lower leaves of the plant and work their way up.
Telltale Signs: If you suspect spider mites, you can use a white piece of paper and shake the plant over the paper. If mites are present, you will see tiny specks moving on the paper.

If you notice any of these symptoms or signs of spider mites, it is important to take action immediately to prevent a full-blown infestation.

Organic Methods

When it comes to treating spider mites on cannabis plants, there are a variety of organic methods that can be effective. These techniques can be a great option for growers who want to avoid the use of potentially harmful chemicals. Here are some organic methods you can try:

  • Prune Infested Leaves: One simple method for treating spider mites is to prune any infested leaves. Removing the affected areas can help slow the spread of the mites and reduce the overall infestation.
  • Apply Neem Oil: Neem oil is a natural insecticide that is effective at controlling spider mites. It works by disrupting the mites’ feeding and breeding patterns. To use neem oil, dilute it with water and apply it to the affected plants with a spray bottle.
  • Use Organic Pest Control Products: There are a variety of organic pest control products on the market that can be effective against spider mites. Look for products that contain plant-based ingredients like pyrethrum or rosemary oil.
  • Introduce Beneficial Insects: Predatory insects like ladybugs and praying mantises can be effective at controlling spider mites. These insects feed on the mites and can help reduce the infestation. You can purchase beneficial insects online or at a local gardening store.
  • Clean and Maintain Your Grow Room: Practicing good hygiene in your grow room can help prevent spider mites from taking hold. Regularly clean your room and equipment, and make sure to remove any debris or dead plant matter. Additionally, make sure to keep the humidity levels in your grow room at an appropriate level, as spider mites thrive in dry environments.

Remember that these organic methods may take longer to be effective than chemical options, so it’s important to be patient and persistent with your treatment. You may need to implement multiple methods in combination to fully control the infestation.

Chemical Methods

When it comes to eliminating spider mites from your cannabis plants, chemical methods can be an effective solution. However, it is important to note that these should be used as a last resort and with caution, as they can also harm beneficial insects and the overall health of the plant. Here are some options for chemical treatments:

Treatment Description
Pyrethrins This is a natural insecticide derived from chrysanthemum flowers. It is safe for humans and pets and can be effective against spider mites when used correctly. However, it also kills beneficial insects, so application should be targeted and not excessive.
Neem Oil Another natural remedy, neem oil disrupts the life cycle of spider mites and can prevent them from reproducing. It is also harmless to humans and pets. However, it can leave a residue on the plants and has a strong odor, so proper ventilation is important.
Insecticidal Soaps These soaps work by suffocating the mites and can be applied directly to the plant. They are safe for humans and pets, but can also harm beneficial insects. It is important to follow the instructions carefully and not overapply.
Acaricides These are specifically designed to kill spider mites and other mites. They can be effective, but should only be used as a last resort as they can harm beneficial insects and the environment. It is important to follow the application instructions and not use these products near water sources.

It is important to always wear protective gear when using any chemical treatments and to follow the instructions carefully. Overuse or misuse can lead to harm for both the plant and the environment. It is also recommended to use natural or organic methods whenever possible.

Removing heavily Infested Plants

When it comes to removing heavily infested plants, it is important to do so carefully in order to prevent the spread of spider mites to other plants in the growing environment. Here are some steps to take when removing heavily infested cannabis plants:

  • Isolate the plant: First, isolate the heavily infested plant from other healthy plants to prevent the spread of spider mites. Move the plant to a separate area, preferably outside of the growing area.
  • Bag the plant: Once the plant has been removed from the growing area, bag it in a secure plastic bag immediately. This will help to contain the spider mites and prevent them from spreading to other plants in the area.
  • Dispose of the plant: After the plant has been bagged, it should be disposed of properly. This can be done by either burning the plant or placing it in the trash, but it should not be composted as the spider mites can survive in the soil.
  • Clean and disinfect: After the heavily infested plant has been removed and disposed of, it is important to thoroughly clean and disinfect the surrounding area. This will help to eliminate any remaining spider mites and prevent them from spreading to other plants. Use a commercial cleaning solution or a mixture of water and rubbing alcohol to wipe down all surfaces, including walls, floors, and equipment.

Remember, removing heavily infested plants should only be done as a last resort. Prevention and early detection are the best methods for dealing with spider mites on cannabis plants.


In conclusion, dealing with spider mites on cannabis plants requires a combination of prevention and treatment methods. Prevention is always the best approach, and growers can take several steps to minimize the risk of spider mite infestations. These include keeping cannabis plants healthy through proper watering, nutrition, and light exposure. Additionally, regularly cleaning and disinfecting the grow room can help prevent the spread of spider mites. Growers should also take care to avoid cross-contamination by not introducing new plants without proper quarantine measures. Introducing predatory insects, such as ladybugs or spider mite predators, can also help keep spider mite populations in check.

If prevention methods fail, growers need to be able to identify spider mites and determine the severity of the infestation. Once identified, growers can choose to use organic methods, such as neem oil or predatory insects, to treat the infestation. Chemical methods, such as insecticides, can also be effective but should be used with caution to minimize harm to the cannabis plant and any beneficial insects present. In some cases, growers may need to resort to removing heavily infested plants to prevent the spread of the infestation to other plants.

Overall, understanding how to recognize and treat spider mites on cannabis plants is important for any grower to ensure the health and vitality of their crops. By taking proactive preventative measures and reacting appropriately to signs of an infestation, growers can successfully manage spider mites and maintain happy and thriving cannabis plants.

Frequently Asked Questions

What is the ideal temperature for preventing spider mites?

The ideal temperature for preventing spider mite infestation is within the range of 20-30°C (68-86°F).

How can I keep my cannabis plant healthy to prevent spider mite infestation?

You can keep your cannabis plant healthy by providing adequate space, light, nutrients, and water, as well as regularly inspecting and removing any dead or diseased leaves.

What type of predatory insects can I introduce to control spider mites?

You can introduce predatory insects such as ladybugs or predatory mites to control spider mites.

How do I identify spider mites?

Spider mites can be identified by tiny white or yellow spots on the leaves and webs between the leaves and stems.

What are some organic methods for treating spider mite infestations?

Some organic methods for treating spider mite infestations include using neem oil or insecticidal soap, as well as regularly spraying the plants with water.

What chemical methods are effective in treating spider mites?

Chemical methods such as using miticides or insecticides can be effective in treating spider mites, but they may also harm beneficial insects and may require several applications.

What should I do if my cannabis plant is heavily infested with spider mites?

If your cannabis plant is heavily infested with spider mites, you may need to remove the plant completely to prevent the infestation from spreading to other plants.

How do I clean and disinfect my grow room to prevent spider mite infestations?

You can clean and disinfect your grow room by removing any debris or dead plant material, wiping down surfaces with a bleach solution, and using a HEPA filter to reduce the spread of airborne spores or pests.

Can spider mites affect the quality of my cannabis yield?

Yes, spider mites can affect the quality and yield of your cannabis by causing leaf damage and decreasing resin production.

Are spider mites harmful to humans?

While spider mites do not pose a direct risk to human health, their webs and fecal matter can cause respiratory irritation in sensitive individuals.


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