Spider mite infestation

How to Get Rid of Mites on Cannabis Plants: Keep Pests off Your Plants

Picture this, you’re the proud cultivator with a thriving garden full of vibrant cannabis plants, only to wake up one day to see them infested by what looks like mere specks of dust. They are tiny, they are many, and they are… the dreaded mites.

Oh these hungry little suckers are small but they are mighty and an infestation can seriously damage your grow as the mites suck the sap right out of the plants.

In this comprehensive guide, I have gone deep into the world of mites on cannabis plants in order to teach you how to tackle this pest problem head-on.

Spider mites on cannabis plants
Spider mite on infested leaves

So What are Mites in the First Place?

Mites are micro-arthropods that are part of the Arachnid family. That is really just a fancy way of saying that they are relatives of spiders and scorpions. They are common pests on both indoor and outdoor plants and they can cause considerable damage to your cannabis plants because they feed on the sap of the plant cells. This results in malnourished plants that eventually display signs of distress, such as stunted growth, yellowing leaves, and overall poor health.

Types of Mites on Plants

Plant mites come in various forms, with the most common ones being the spider mite and the russet mite. Both have unique characteristics and distinctive patterns of damage.

Spider Mites

Spider mites are notorious for spinning fine, silk-like webs on plant foliage, hence their name. They are typically light green or red, and they tend to thrive in hot and dry conditions. As these mites feed on plant cells, they leave a characteristic stippled or spotted appearance on the leaves. The most common types of spider mites are the two-spotted spider mite and the red spider mite.

Spider mite close up
Spider mite

Russet Mites

Russet mites are much smaller than spider mites, making them harder to detect which can cause them to go undetected until significant damage is done. They directly damage the plant by sucking the sap from the lower part of the leaves and the flowers, leading to a bronzing or “russeting” effect. Russet mites are so small that they cannot normally be seen with the naked eye. Because of that, their damage is often misdiagnosed for a nutrient deficiency.

Mites on plants
Russet mite hurting the leaf

Symptoms of Mites on Cannabis Plants

Recognizing a mite infestation early can help save your plants from severe damage but it can be very difficult to do. In some cases, you need to have a magnifying glass handy in order to even see the mites so if you spot mites on your plants you should consider yourself lucky that you know what the problem is. Here are some signs that your cannabis plant might be suffering from a mite infestation.

  1. Insects and Other Pests Attracted by Mites — An infestation can create a vicious cycle, as mites attract other pests like ants (especially on outdoor plants), who come for the honeydew (a sugary substance) that mites secrete. If you spot ants walking in formation to specific parts of the plant you can be fairly certain that you have mites.
  2. Webbing — In the case of spider mite damage, fine, silk-like webs are seen on the undersides of the leaves and between branches.
  3. Damage to Plant Leaves — Even if you don’t see visible mites or webs on your plants, you may still be suffering from an infestation. If you see yellow or brown spots on the leaves that make you think you have a nutrient deficiency it may be because the mites feed on the sap inside the leaves. This leads to the destruction of chlorophyll which eventually lead to completely yellow leaves.

Early identification is key in controlling mite infestations. Regularly inspect your plants, especially the undersides of leaves, using a magnifying glass or even a white sheet of paper under the leaves to spot falling mites.

What do mites look like on plants? Depending on the type, mites may look like small specks of dust, tiny spiders, or even minuscule white blobs. Spider mites are often red or green, while russet mites are almost transparent.

With knowledge about what causes mite infestations and how to control them, you’re well-equipped to protect your cannabis plants from these pesky pests. So go ahead, arm yourself with that magnifying glass and show these mites who’s boss!

Remember, a healthy plant is less likely to be severely affected by mites. Ensure your plants get the right amount of nutrients, and be on the lookout for symptoms of deficiencies such as nitrogen deficiency, phosphorus deficiency, and potassium deficiency. Keep your plants well-nourished to ward off mite infestations, and if they do occur, your plant is more likely to recover with less damage.

Mites under leaf
Mites under leaf

Causes of Plant Mite Infestations

Anyone can get hit by mite infestations so if you have it once or twice on isolated plants, you should not worry too much about your skills as a grower. If it’s a consistent issue for you though, you need to consider adjusting your growing technique and to make sure that you create an environment that is beneficial to your plants while not allowing pests to thrive.

There are two common factors that contribute to a mite infestation and understanding them can help in preventing future outbreaks.

Lack of Natural Predators or Enemies

In a natural ecosystem, predators keep mite populations in check. However, in an indoor growing setup, this balance is often lacking, leading to unchecked growth of mite populations. Consider using a microbial inoculant with beneficial bacteria to keep your plant strong, healthy and prepared to fight off pests.

We recommend trying Amplify to your grow!

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For outdoor growers, encouraging a favorable environment for natural mite predators is important too.  Predatory insects, such as ladybugs and lacewings, are natural enemies of mites and they help greatly in controlling mite populations.

Treating plant leaves with insecticidal soap or neem oil can be very helpful in reducing the risk for mites. Regularly spraying your plants with an organic insecticidal soap or neem oil can kill mites before they become a problem.

Dry Conditions

Mites love hot, dry environments where they can reproduce and safely feed on plant sap. If you’re growing indoor, it’s crucial to manage temperature and humidity levels properly to avoid creating a conducive environment where mites thrive. Don’t let the humidity drop too low (also not too high or you may get a problem with mold instead).

Seedling Stage — The ideal relative humidity (RH) is around 65-70% as the cannabis seedlings require a high humidity level because they are not yet efficient in water uptake through their roots so the seedlings primarily take in water through their leaves.

Early Vegetative Stage — Gradually decrease the humidity to around 50-70%. Reduce the humidity slightly to encourage the plant to utilize its roots more. However, it’s still important to maintain relatively high humidity to prevent the plant from drying out and to promote vigorous growth.

Late Vegetative — The humidity should be decreased further to about 40-50% to prepare the plants for flowering.

Early Flowering Stage — Humidity levels should still be around 40-50% at the start of flowering, gradually decreasing to around 30-40% by the end of the stage. It’s crucial to lower humidity during this stage to prevent mold and bud rot.

Late Flowering Stage — In the last week or two before harvest, some growers choose to drop the humidity even further, to around 30%. This final drop in humidity can help to boost resin production even further and help to prevent mold during this crucial stage.

*More on humidity & temperature here

Learn how to spot and fix cannabis nutrient deficiencies

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