By Gooey Rabinski

Labeled by gardeners as the most common–and potentially costly–threat facing modern cannabis cultivation is the common mite. Indoor or out (they are especially troublesome in greenhouses), the problem is the same: Mites are ever-ready to pounce on your pot plants.

The extreme commonality of mites in cannabis gardens means that all cultivators and farmers must be ever vigilant. The goal is to stop any threat before significant damage is caused to one’s harvest–along with decreased production volumes.

In gardens suffering an existing infestation, the sole option is obviously an eradication strategy that preserves as many plants as possible.


Mites typically appear during hot, dry conditions. Infestations advance quickly, often taking cultivators by surprise. Unfortunately, abundant use of synthetic fertilizers has killed many of the natural predators of mites.

Their extremely small size makes mites difficult to detect during casual garden inspections. A magnifying glass or jeweler’s loupe is necessary to properly detect this microscopic menace, especially smaller species.

The most common variety, the spider mite, damages plants by piercing leaf tissue and feeding on fluids and resin. Evidence of feeding includes leaves featuring light yellow spots which, if untreated, will turn fully yellow or brown and fall from the plant.

A fine webbing on plants indicates a large colony of spider mites and a severe infestation. Routine inspections, if performed thoroughly, are an opportunity to detect these pests before they wreak extensive damage. Unfortunately, the much smaller russet mite leaves no such webbing, making it significantly more difficult to detect.


Any cannabis cultivator will eventually encounter a mite infestation of one severity or another. When evidence of mites is first detected, quick action is necessary to prevent rapid expansion.

Novice farmers, at the first sign of an infestation, often panic and are tempted to apply synthetic pesticides to their plants. Unfortunately, this approach can be counter- productive for multiple reasons.

First, synthetic pesticides kill beneficial predator insects, meaning they can, ironically, result in the spread of an infestation. Second, mites have shown a tendency to develop a quick resistance to many common pesticides. Thus, the best approach to the treatment of mites is one involving organic methods.

One strategy for heavy mite infestations is the use of a soap spray or an organic pesticide to decrease the mite population–after which predator insects are employed to fully rid the garden of intruders. Predator bugs offer the additional benefit of helping prevent future infestations.


Mite infestation can occur from many sources, including unsealed grow rooms, human clothing, pets, and even dirty equipment. Ensuring the cleanliness of grow environments and greenhouses–and those working in them–is important to minimizing a garden’s exposure to attack.

In addition to cleanliness, one of the most effective means by which to prevent mite attacks is the introduction of predatory insects. These include praying mantises, ladybugs (which also munch on aphids, another common pest to cannabis plants), and predatory mites (like the persimilis variety, which gorges on spider mites).

Among the most effective commercially available predator varieties is the western predatory mite, which is most helpful in dry, hot conditions. The western predatory mite, including similar species, are advantageous because they do not feed on cannabis plants; if damaging mites aren’t available for a quick meal, it will either die or migrate to another food source.