By Luke Sumpter

Cannabis might be a hardy plant, but it's also prone to pests and pathogens that can significantly affect the quality and size of your harvest. One way to manage cannabis pests is to use biological pest control. Keep reading to learn how biological cannabis pest control works and why it's becoming ever more popular.

What Exactly Is Biological Pest Control?

Biological pest control refers to the method of using living organisms to control pests in your grow room or garden. These organisms include:

  • Beneficial bacteria and fungi
  • Insects that prey on pests
  • Plants that naturally repel pests and pathogens or attract beneficial insects

Biological Pest Control vs Synthetic Pest Control

As opposed to using living organisms to control pests, synthetic pest control uses synthetic chemicals such as:

  • Pesticides
  • Fungicides

A man using pesticides on Cannabis Plants
A Man Using Pesticides on Cannabis Plants

Chemical pesticides are carefully formulated to eradicate one or multiple types of pests. They can work in a number of ways; by killing pests upon contact, by affecting their ability to reproduce, or by influencing the pest's behaviour in a detrimental way (for example, some pesticides may cause pests to stop eating or drinking water).

Chemical pesticides and fungicides are generally very effective and fast-acting, and many growers turn to them when they're facing a large pest infestation that needs to be controlled immediately. Unfortunately, however, chemical pest control agents aren't always very selective and may kill beneficial insects living in your garden, such as those listed further down in this article.

Plus, the harsh chemicals present in pesticides/fungicides can contaminate your cannabis flowers, as well as damage your soil and contaminate the runoff from your garden. For those reasons, many cannabis growers choose to use biological pest control methods wherever possible, as they offer a non-toxic, eco-friendly, and sustainable alternative.

The Pros and Cons of Biological Pest Control

Every approach to growing cannabis has its own set of benefits and drawbacks, and biological pest control is no different. Below, we'll outline the pros and cons of using biological pest control in your cannabis garden so you can decide if it's the right approach for you.

The Benefits of Biological Pest Control

  • Sustainability: Unlike synthetic pesticides/fungicides, biological pest control methods do not produce harsh chemical runoff that can pollute the local environment. Biological pest control methods also do not disturb or degrade soil, meaning you can reuse the soil used to grow your cannabis plants post-harvest.
  • Non-toxic: Chemical pesticides and fungicides contain chemicals that are toxic to humans, pets, and the beneficial insects and bacteria living in your garden. Biological pest control, on the other hand, is free of these harsh chemicals.
  • Specificity: Biological pest control focuses on introducing organisms into your garden with very specific targets. That means that it allows you to control a certain pest without damaging any other organisms in your garden/grow space.
  • Cost-effective: Biological pest control takes a proactive approach to dealing with pests, and focuses on creating a good environment for your plants that doesn't favor the spread of pests and pathogens. While this approach is more hands-on, it helps to prevent pest infestations rather than just treat them, and can therefore save you money in the long run.
  • Long-term: Biological pest control offers a long-term solution to pest management. Once you introduce them into your garden, many of the beneficial insects, plants, and other organisms we list below sustain themselves with little-to-no input on your behalf. Plus, the fact that they won't disrupt other plants or animals in your garden means that biological pest control methods can be kept in place for much longer periods of time than synthetic pesticides/fungicides, which can damage your plants when used in excess.

Ladybugs as Biological Pest Control
Ladybugs as Biological Pest Control

The Disadvantages of Biological Pest Control

  • It's a slow process: Biological pest control is a long-term endeavour. Introducing beneficial insects and plants into your garden may seem simple, but it can take considerable time for these organisms to start producing an effect, especially when compared to the immediacy of using pesticides and fungicides.
  • It's not a permanent solution: Biological pest control won't completely eradicate a pest from your garden.
  • It's less controlled: No matter how much we might try, there is no controlling nature. Sometimes, introducing organisms into your garden to prey on a particular pest works; sometimes, it simply doesn't. Oftentimes, finding a biological method of controlling pests that works and suits your garden takes time and some trial and error.

Using Biological Pest Control: Indoor vs Outdoor Cannabis Cultivation

Below, we'll walk you through different ways to use biological pest control in your cannabis garden. While some of the methods might seem more applicable to indoor rooms/tents and others might seem more suitable for an outdoor space, they are not mutually exclusive. Feel free to experiment with each method as you see fit, and follow the links provided for more information.

Using Biological Pest Control Indoors

First, we’ll start with bio pest control measures primarily implicated for indoor use.

Foliar Spray

  • Foliar sprays are one of the most popular ways to apply commercial insecticides and pesticides. However, they also play their part in biological pest control. Some organisms you can apply directly to your plants in the form of a foliar spray include:
  • Compost tea: Made from compost, compost teas are rich in nutrients as well as bacteria that can help to protect your plants from pathogens and pests. Rather than using compost, you can also make foliar leaf teas from worm castings or guano, which also contain natural bacteria and fungi that'll help protect your plants.
  • Neem oil and potassium soap: While not technically living organisms, neem oil and potassium soap are by far two of the most effective organic pest control agents out there.


Nematodes are microscopic worm-like animals that, when used properly, can be a huge asset to your cannabis garden as they hunt and kill both pests and their larvae. Nematodes can be very effective against a variety of pests, from ants and ticks to caterpillars, gnats, and leafminers.

The best way to use nematodes in your favor is to buy them from a reputable supplier and introduce them into your soil. Most nematodes come in the form of some kind of carrier (such as vermiculite) that you can introduce directly into the soil.


Often thought of as a specific type of fungi or bacteria, mycorrhizae actually describes the symbiotic relationship between a plant's roots and a network of beneficial fungi. When you take the time to create a rich, organic soil for your plants, these fungi are able to grow around their rhizosphere, helping to maintain both the health of the soil and your plants. For example, mycorrhizae can help your plants take up more nutrients from the soil as well as protect them from pests and pathogens.

The best way to use mycorrhizae is to inoculate your soil with beneficial bacteria before you sow your seeds; in fact, mycorrhizae is very effective at protecting seedlings and is known to benefit the development of their roots.

Biological Pest Control for Outdoor Cannabis Cultivation

While most of the aforementioned indoor pest control options are also viable outdoors, below are some measures that are more specific to outdoor crops.

Companion Planting

Companion planting is all about giving your cannabis plants some "companions". Certain herbs, for example, naturally repel pests with their unique aromas. Flowers or fruit trees and vegetables, on the other hand, help to attract pollinators and other insects that naturally feed on smaller insects (such as plant pests). Finally, companion planting also adds to the biodiversity of your garden, making it harder for pests and pathogens to settle in, as it's much easier for them to strike monoculture crops.

Beneficial Insects

Last but definitely not least, another great way to adopt biological pest control is by introducing beneficial insects into your garden to prey on pests. Some popular insects used to protect cannabis and other plants include:

  • Ladybugs: Can help control aphids, moths, beetles, mites, and thrips, as well as their larvae.
  • Lacewing larvae: While adult lacewings are herbivores, lacewing larvae feed on aphids, thrips, whiteflies, leafhoppers, and spider mites.
  • Praying mantis: These unique-looking specimens hunt aphids, caterpillars, and whiteflies.
  • Nematodes (see above).

Other beneficial insects for your cannabis garden include assassin bugs, predatory mites, and rove beetles. Some of these insects can be bought from garden centers, but companion plants can help to attract them into your garden for free!

Parasitics Wasps

Parasitic wasps are a popular choice of beneficial insect that naturally prey upon aphids. They also attack various beetles, flies, spiders, and bugs. Endoparasitic wasps inject their eggs inside of their prey, which develop over time as the prey continues its normal functions, whereas ectoparasitic wasps develop on the outside of their prey and paralyse it instantly.

Wasps Biological Predator Cannabis


Spiders are very helpful creatures within cannabis gardens. They spin vast webs and are no picky eaters. These will feed on a large variety of different pests. Planting flowers within your garden will help to attract spiders.

Spider Natural Predator In Cannabis Plants

What Is the Best Pest Control Method for Cannabis?

As growers, we're always on the lookout for the best way to promote the health of our plants and thereby enjoy a high-quality harvest. When it comes to pest control for weed plants, we see most growers opt for a hybrid approach that allows them to reap the rewards of both biological and synthetic pest control methods.

For example, growers might inoculate their soil with nematodes and mycorrhizae at the beginning of their grow, and use companion planting to try to prevent pests from settling into their garden. When facing an infestation, however, they may turn to synthetic pesticides and fungicides to deal with the situation as soon as possible, before slowly returning to a more biological and eco-friendly approach.

The truth is that there's no one-size-fits-all approach to dealing with cannabis pests. Finding the right approach will depend on your skills and preferences as a grower, as well as the type of setup you're running. In most cases, however, a hybrid approach works great.

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