Everything you need to know about growing cannabis at home

Everything You Need to Know About Spider Mites and Cannabis Plants

by | May 9, 2022 | Cannabis, Environmental Threats, Pests, Troubleshooting

Spider mites are a predatory mite that can cause a lot of problems for your garden. They feed on plant juices and leave behind webbing, which will cause leaves to fall off prematurely. This article will detail spider mite symptoms, prevention methods, and treatment techniques.

What are spider mites?

Spider mites are a type of arachnid and are a common pest that feed on healthy plants. Twospotted spider mites, which are also known as Tetranychus urticae, are one of the most common mite species found in gardens. These pests can be identified by their spider-like appearance and the webbing they produce. Spider mites thrive in hot, dry conditions with plenty of sunlight, so it’s important to make sure your garden is well maintained and watered during these types of weather patterns. Spider mite bites will cause infested leaves to appear yellow or brownish in color, but if spider mites aren’t dealt with quickly, the damage will spread throughout the entire infested plant.

Spider mites look like spider-like organisms with eight legs. Spider mites reproduce very rapidly; one adult female spider-mite can lay up to 20 eggs per day which results in hundreds of offspring within the span of about 30 days. They are usually red or brown and can be anywhere from the size of a pinhead to visible to the human eye. Their life cycle can last anywhere from a few days to several weeks.

What conditions are conducive to having spider mites when growing cannabis?

Spider mites prefer hot and dry conditions, but spider mite infestations can happen in any weather or climate zone. The ideal conditions for spider mites are hot and dry conditions with plenty of sunlight. Spider mites don’t need a lot of water to survive but they will thrive in perfectly maintained gardens that are very well-watered.

What are the symptoms of having spider mites on your cannabis plants?

Spider mite bites first appear as yellow or brown speckles on the leaves of your plant. You may also see spider mite webbing on the leaves and stems of your plant. If spider mites are left untreated and it becomes a heavy infestation, they will cause yellowing and wilting of vegetation as well as prevent plants from flowering or producing fruit.

Spider mites damage plants by piercing the plant tissue with their mouthparts and rasping up cell contents, which they suck out. This rupturing weakens or kills the entire leaf cell as well as surrounding cells. The leaf or spiderweb-like appearance of damaged leaves is due to this spider mite feeding activity as well as their molting process, in which an old exoskeleton is replaced with a new one. As spider mites feed, a fine webbing can be observed on the plant surface, and leaves may have leaf stippling, which means damage done by leaf sucking pests, or bronze from feeding damage.

As spider-mite populations grow, being webspinning mites means they will spin webs to protect themselves as well as their potentially hundreds of eggs from predators such as lady beetles and ladybugs. If you have spider mite infestation, an entire branch or plant can be covered in webbing with small insects crawling all over it. Leaves will turn yellow and drop off early when there is spider mite damage. This damage to leaves also makes them more susceptible to mold growth as well as other spider mite infestations. If you notice spider mite infestations in your garden, spider mites can be treated through organic or chemical means.

What is the life cycle of a spider mite?

The spider mite life cycle consists of four stages: egg, larva, nymph, and adult. Spider mites typically spend the winter as adult mites in protected areas such as leaf litter or other debris. They can be carried to new locations on animals, including humans, wind currents, and even garden tools. Spider mite eggs are about 0.04 millimeters long and usually hatch within seven days.

How do you treat spider mites on cannabis plants?

If you are experiencing a spider mite outbreak, the first thing to do is remove all of the affected leaves and branches immediately. Be sure to wash down any surfaces that may be a host for spider mites as well as make sure there are no eggs still left in spider webbing.
After you remove all affected plant matter and spider mites, it’s important to ensure that your garden is well watered and maintain healthy soil conditions for optimal growth. Organic pesticides such as neem oil can also be used to treat spider mite infestations naturally. The oil is from the neem plant and is an all-natural horticultural oil spray that can be found at most garden centers.
A home remedy for spider mites includes diluting dish soap in water, about 1 part liquid soap (non-detergent) to 10 parts water, and washing spider mites off of host plants. Be sure to apply this to both the top and bottoms of leaves. This can be used as a preventative measure to kill spider mite eggs before they hatch, but it is not strong enough to treat an infestation on its own.

For cannabis plants, do not use any solution on bud sites and colas when late into flowering. Neem oil is safe but will leave a harsh and bitter flavor to the cannabis when smoking it. If you have spider mites during flowering, we recommend that you allow the plant to get as close to the ideal harvest time and then chop it. Then you can use a bud washing method to clean the plant without affecting quality.
Beneficial insects may also be used as spider mites have natural predators that won’t hurt plants. Ladybugs are spider mites’ natural enemies and will eat spider mite eggs, larvae, nymphs, and adults on certain plants. These beneficial predators are widely available online for cheap.

How can you prevent spider mites on cannabis plants?

Prevention is always key so it’s important to maintain clean and healthy conditions for your plants, especially during hot summer weather when spider mite infestations are more likely to occur. It’s also a good idea to place yellow sticky traps near your garden or greenhouse as these can attract spider mites away from your plants. To keep spider-mite populations under control, make sure that your garden is spider-mite-free before planting. Ensure that there’s no mulch or debris in the immediate vicinity of affected areas, and water plants early in the day so they have time to dry out by evening should you have outdoor plants. One of the best ways to keep spider mites away is through sanitation practices including removing all plant debris at the end of each growing season as well as ensuring that all garden tools and surfaces are clean.

If you’re having trouble treating spider mites on certain garden plant varieties, use a greenhouse cover for added protection against spider mites. If spider mites are a prevalent problem in your area, you can grow spider mite-resistant varieties of plants such as Siberian irises and daylilies to keep spider mite problems at bay naturally. Some people believe that applying petroleum jelly or oil on the trunks of trees will prevent spider mites from climbing up the tree although it is unproven.

For indoor cannabis plants, we recommend a weekly dousing of neem oil or the above-mentioned soap and water solution right before lights out. Be very thorough in spraying both the top and undersides of leaves and on the topssoil. If the water is on the plant all day with the lights on, the droplets may burn the leaves. As mentioned above, do not do this if the plant is in late flowering as it can affect the quality of the cannabis. This should prevent these and other pests from terrorizing your garden.


Spider mites are an arachnid species that are very small and reproduce quickly. They thrive in dry, hot weather conditions with a lot of sunlight although watering your plants in a garden will not be a deterrent. If your cannabis plants have spider mites, you may notice little brown or red specs moving on either side of your leaves. These pests feed by sucking the sap from your plant which can cause the leaves to bronze and die. They also leave behind troublesome webbing, especially for cannabis plants.

To treat spider mites you can use neem oil or a homemade solution of non-detergent soap and water. Preventing spider mites requires weekly spraying of your plants with the same neem oil or soap water solution. Yellow sticky traps, although mostly used for fungus gnats, also can help prevent an infestation. It also helps to make sure your garden is spider mite-free before planting.

To learn more about growing cannabis at home consider checking out our guides on: Getting Started, Troubleshooting, and Optimizing your Grow or search our Knowledge Base.

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