Spider Mites on Weed Plants

Pest Problems: Spider Mites on Weeds and Bugs

Pest infestation is a common and frustrating problem, particularly in the growing cannabis industry. These pesky creatures, including spider mites and other bugs, threaten new and experienced growers significantly. As such, concerned ‘farmers’ need to plan a solution at some point during their farming journey.

The signs of spider mites on their farms can be particularly alarming, as the problem can quickly escalate if left unchecked. Pests are more likely to cause problems during the vegetative growth stage. A plant’s susceptibility to infestation largely depends on environmental conditions and fertilization practices.

Learn more: Weed Fertilizer Tutorial

This article explores effective methods to reduce pest risk on your farm and how to handle an infestation. Nevertheless, this context focuses on spider mites – a common concern for marijuana growers.

cannabis mites

What are Spider Mites?

Spider mites are a member of the mite family. They have a close ‘bloodline’ with ticks and spiders and are widely considered more as arachnids than insects.

These tiny-sized mites have eight legs and no antennae. Pests may not be seen even with a magnifier, which makes it even a more significant threat, as it is difficult to foresee an infestation on your farm. They were named not just because of their spider-like eight limbs, but for the tiny silky web spins, they formulate on your plants. It is their unique way of protecting themselves against predators. 

Although spider mites have different species, almost the same eradication and prevention methods apply for all types. 

The infestation can be fast and destructive when spider mites appear on your farm. Whenever you notice an infestation sign, it is most likely that thousands – or even millions of eggs have laid.

Even more disturbing is their rapid breeding cycle. Typically, eggs hatch within three days. The mites are matured and ready to start another breeding cycle by the fifth day after hatching. A catastrophic infestation could occur just days after you thought your cannabis farm was pest-free.

cannabis plant no mites

Where Do Spider Mites Emerge?

Outdoor or soil-grown cannabis is the preferred target of spider mites. These little creatures thrive in dead organic soil matter and tend to breed and spread faster when the cannabis plants are grown in close ranges.

Spider mites thrive on chlorophyll, a compound responsible for the plant’s green color, which supports photosynthesis.

These insects bite through plant cells with their teeth and feed on chlorophyll. These pests drain the chlorophyll content and limit the plant’s capability to perform photosynthesis.

Malnourishment and eventual death is the outcome effect of a chlorophyll-starved plant. Now, you see how an infestation can majorly ruin your weed. If you get so lucky, you may still get poorly formed cannabis buds on your harvest.

Tips to Spot Spider Mites on Cannabis Farm

Early detection – that’s the primary key to getting rid of spider mites. The best professional advice you can get on this is to inspect your cannabis plants daily for infestation signs. Check to ensure the flowers are well-formed, flat, straight, and with vibrant colors.

Also, watch for their growth rate to ensure their growth pattern is typical of the specific strain. Indica strain, for example, usually comes with dense and short leaves, compared to Sativa. So, if your Indica buds are growing lean and tall, it’s normal to feel concerned.

Malnutrition, poor lighting, mildew, extreme temperature, and humidity increases your plant’s exposure to spider mites and related infestation. Again, the most efficient preventive measure is to ensure your plants are in great shape. Ensure that you have the relevant knowledge and materials to create a conducive environment for your plants throughout their lifespan.

Learn more: Temperature & Humidity Tips

Since Spider mites are invisible to the naked eyes, you may remain unaware of an infestation until it gets out of hand.

The use of a magnifier could come in handy. Without magnifiers, you can still notice an infestation with whitish spots on the leaves, caused by low chlorophyll. As the infestation increases, you’d see tiny silky web buildings on your plant. If this happens, act fast if you want to save your farm.

Spider Mites Prevention

Prevention is vital when it comes to infestation. You’d be better off applying preventive measures than assuming they are not present on your farm.

First, for soil-based practice, spray organic mulch and compost on the plant. These things contain predators that eat up the mites before they create and establish a threatening colony.


Ladybugs are also highly beneficial to marijuana farmers. These bugs feed on spider mites, preventing a significant infestation. Ladybugs are available in online stores. Besides, they can be applied both indoors and outdoors.

For outdoor applications, releasing ladybugs at dusk prevents them from flying away. They settle in over the night and begin their mite-eating duty by dawn.


Garlic works fine as an effective deterrent for pests, including spider mites. For an efficient solution, soak your garlic cloves for several days in water. You may also grind with a blender and apply it with a spray. 

Repeat the treatment monthly for the best result. While it is best for prevention, it can also treat a minor infestation.

spider mites healthy cannabis plant

Eliminating Spider Mites Infestation

You should not handle an infestation with the use of kid gloves.

If the spider mites have formed a colony in your cannabis farm, the chances of losing the pest battle are pretty high; that is why the fast and decisive approach is a must.

These measures could be time and financially consuming. Here are some practical steps to save your plants from a severe spider mites infestation.

Hard Water Spray

Hard Water Spray helps knock off mites and their eggs from your leaves. However, a single treatment is not sufficient – repeat application until you see good results.

While this method works against spider mites, this application can also be dangerous for your plant. Therefore, use this approach with precautions and only if it seems the only way at your disposal.


Vacuuming your leaves and plants helps eliminate spider mites and their eggs. Vacuums with a small-mouthed hose will be gentle on your plant.

Run your fingers

You can also rub off the pests and their eggs by running your fingers over the leaves. For better results, you may repeat this process a few times over in weeks. Although time-gulping, this treatment works for minor infestations. 

Neem Oil

Neem Oil is a popular and effective treatment against pests. The oil stops insects from feeding, stunting their growth, and restrains their reproduction. The application of neem oil must strictly follow.

To prepare, mix two tablespoons of Neem oil and half teaspoon of Coco Wet agent in a gallon of water. Apply the solution on your plant with a sprayer for seven strict treatments, with the following routine:

Three-day intervals between the first three treatments while there should be five-day intervals between the last four treatments.

Alcohol Solution

Solutions with up to 30% isopropyl alcohol may also come in handy for exterminating spider mites. As with Neem oil, you’ll need to mix a gallon of the solution with about half a teaspoon of Coco Wet agent. 

Apply with either a sprayer or soak cotton balls in the solution and rub on each leaf. Continue the treatment until the mites are eradicated.

Diatomaceous Earth

It is a natural anti-pest made from the remains of tiny sea creatures. The fine powder should sprinkle on the leaves. The Diatomaceous Earth has sharp little edges that slit the mites’ outer shell, causing dehydration.


Spider mites’ infestation on your cannabis farm requires a fast and effective measure to get rid of the annoyingly fast-spreading creatures. If you are not fast enough, these little creatures could cause enormous damage, which may ruin your efforts and leave you empty-handed in just a week or two. 

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