Organic growth is focused on the big picture, on sustainable plant growth that benefits the whole ecosystem. In the Foundations of Fertilizer, we covered how organic fertilizers are more environmentally friendly and better for your grow than synthetic fertilizers. In this post, we’ll be talking about how you can avoid synthetic pesticides and pesky pests through the integrated practice of companion planting. 

Pesticides of the Past

Agriculture vehicle in field spraying synthetic pesticides on a crop at dawn
Synthetic pesticides were the agricultural solution to increased global demand for food. However, the environmental impact of certain chemicals is outweighing their benefit.

For centuries, pests and disease have destroyed crops, threatening food supply and the livelihoods of farmers around the world. The first known use of pesticides was by the Sumerians, over 4500 years ago, who used sulphur compounds to deter insects from their fields. These naturally derived pesticides were common until the 1940s when synthetic pesticides made their first appearance.

Chemical pesticides helped to drive the late 20th century agricultural revolution, a time period where agricultural production skyrocketed to match the rapidly growing global population. Crop-duster planes, built to spray pesticides and fungicides onto acres of farmland, became the norm. It was not until years later that these chemicals were found to have some very serious side-effects.

The shift in public opinion on pesticides was highly influenced by Rachel Carson’s book Silent Spring which, published in 1962, heralded the significant environmental and health impacts of the ubiquitous pesticide DDT. The beginnings of the environmentalist movement is often attributed to her book, with the shocking revelation that DDT had driven bird populations to near extinction. DDT was banned in the United States in 1972. 

In the 1987 Montreal Protocol, another popular synthetic pesticide, methyl bromide, was brought into questioning. With its ozone depleting nature, it was discovered to be contributing to global warming. Efforts began to phase it out. 


river surrounded by agricultural land at dusk with pink clouds reflecting in water; highlighting the dangers of pesticide runoff into water
Chemicals in pesticides can leak from agricultural land into nearby water-sources, contaminating the water.

Pesticides Today

Synthetic pesticides and herbicides, such as the infamous Monsanto product Roundup, are still highly controversial today. Lawsuits alleging that these chemicals cause cancer continue to surface, with many countries going as far as banning the products entirely. These bans are backed by growing evidence that these toxic compounds can be passed on to children, contaminate waterways, and act as disease causing agents with sufficient exposure. 

These findings have led to an increased demand for organic pesticides and biological control agents. Having a rich soil ecosystem that promotes plant health is the best start, as healthy microbes and fungi outcompete harmful pathogens. The next step is integrated pest management.

Integrative pest management is an approach that focuses on reducing and preventing pest infestation. Included within is the practice of companion planting.


Ecosystems & Symbiosis

Ladybugs eating aphids on the stem of a purple plant; highlighting the mutually beneficial relationship between plant and ladybug
Ladybugs and plants share a mutually beneficial relationship. Ladybugs will eat aphids on plants, benefitting from the food-source and a place to lay their eggs. The plant benefits from the aphid pest-removal.

When solving problems, it’s always best to work as a team. In nature, it’s no different. Natural ecosystems that allow animals and plants to thrive are full of symbiotic, or mutually beneficial, relationships. The unlikely pairing of a remora fish and a shark is a great example. 

More relevant examples can be found in the soil, where beneficial bacteria and helpful fungi support their host plant. These microbes form a hidden network that passes on nutrients, while protecting your plants from disease and stress.


What Are Companion Plants?

Companion planting is a common organic agricultural practice, and a form of symbiosis. It involves growing two or more plant species close together, where one plant provides the other with insect deterrence, weed suppression, increased nutrient supply, and nutrient retainment. Companion planting is a natural alternative to synthetic pesticides.


How do companion plants deter pests?

closeup of bright orange marigolds, a popular plant for companion planting
Marigolds produce alpha-terthienyl, a substance that is toxic to nematodes. Marigold flowers are attractive to insects with their bright orange colouring, making them a popular choice for companion planting.

Companion plants deter pests through several fascinating mechanisms:

  1. Attract-Annihilate – companion plants known as “trap plants” can attract pests and draw them away. Some trap plants also produce toxins that are lethal to attracted insects.
  2.  Masking – companion plants can prevent pests from recognizing and attacking your plant by interfering with their biological receptors. These plants release chemicals that can deter mating and feeding patterns, or just cause the pests to move away.
  3. Calling for Backup – companion plants can recruit natural enemies of pests by providing them with food and shelter. They can even draw them in with colour and smell alone. For example, the long-rooted yarrow plant is often used to draw in hoverflies and ladybugs, which help to destroy menacing aphid populations. 


Common Companion Plants

Closeup of mint leaves, a popular plant for cannabis companion planting
Mint contains menthol, which acts as a deterrent to insects. Mint grows quickly and easily, and is best planted in a pot near other plants to avoid competing for space and nutrients.

The following plants have been proven to have strong pest-deterrent properties so consider incorporating them into your growing plan:

  • Marigold – repel beetles, nematodes, and leaf hoppers
  • Basil – repels a variety of insects, including aphids, with its sweet scent
  • Rosemary – similar to basil in its ability to repel a variety of insects, such as mosquitos
  • White Mustard – fights nematodes; also incorporated into the soil as a biofumigant
  • Mint – contains menthol which deters insects like aphids and ants, and mice; can be invasive, so best kept in a pot near plants, rather than in the soil itself.
  • Dill – repels spider mites, one of the top disease-causing agents in cannabis
  • Sunflower – distract pests with their bright colour and spiral pattern; hardier than cannabis plants to resist infection


Preventing Resistance

Another great advantage of using companion plants as pest control is that pests don’t develop resistance as quickly. Synthetic pesticides usually rely upon a single chemical compound, which is easier to develop a resistance against. Natural sources are typically composed of many different essential oils and molecules. These create a robust defense that can’t easily be bypassed.


Beyond Pest Control

Closeup of Chilli and lavender plants, as an example of companion growing
Lavender is a companion plant to chilli peppers because it naturally deters slugs and deer.

Organic and conventional growing differ in many ways. Organic growers take a mindful approach, considering the environmental and social impacts of their practices. Their practices support the ecosystem as a whole, avoiding pitfalls such as intensive monoculture. 

Mono-culturing, or the growing of a single crop repeatedly, deprives soils of nutrients. It also causes microbial imbalances that lead to lesser yields and harvest quality. Microbes are the hidden army in your soil, working to promote strong, healthy plants. 

BlueSky Organics Vit-Alive product in a green resealable bag with white and black writing
BlueSky Organics Vit-Alive is an organic compost tea blend. It promotes microbial activity and provides companion and cannabis plants with all of the nutrients needed to thrive.

Growing with companion plants has been demonstrated to improve soil quality and crop productivity. Introducing new plant species increases bacterial and fungal diversity, with benefits that grow stronger over time.


What BlueSky Organics Can Offer

Now that you know all about companion plants and how they can help you take your grow to the next level, the next step is to introduce them into your system. Start with great soil as the foundation, and provide your companion and cannabis plants with nutrients they need to thrive. 

Vit-Alive is a compost tea blend that provides key micronutrients in an easily-delivered format. When used alongside Organic Booster to kickstart a thriving microbial community, you’ll be well on your way to organic growing success. 




All references retrieved on January 12th, 2019.