Auxins, gibberellins, cytokinins, and other cannabis hormones that you’ve probably never heard of (but maybe you should have)

We all know that cannabis plants need light, water, oxygen, and nutrition to thrive. All these factors are considered extrinsic and are certainly vital. But did you know that plant growth also depends on some intrinsic factors? These include a type of intercellular chemicals which are also known as growth regulators, plant hormones, or phytohormones. Here we’ll learn more about them and discover how you can use them to boost your marijuana grow.

Growing cannabis can feel like you’re running a nature show: you have to juggle lights, nutrients, water pH, and lots of other factors. However, one aspect that often goes unnoticed is the hormone system that works tirelessly under the leaves. Your beloved plants have their own miniature chemical messengers (i.e., hormones) that guide them through every step of their development. So, when you think of the “hormones of the cannabis plant”, you’re seeing the invisible directors that orchestrate root growth, flowering, and everything that happens between the birth and death of your plants.

How do cannabis hormones work?

More technically, plant hormones (or phytohormones) are chemical signalling molecules. Just like hormones in animals, these act at extremely low concentrations but have a profound impact, coordinating and regulating virtually all biological processes from cell growth and division to environmental stress responses. The most fascinating thing about these molecules is that they don’t act in isolation but rather as an internal communication system that allows the plant to adapt and thrive in its environment.

These hormones are produced in different parts of the plant (in the roots, shoots, or leaves), and are transported through internal fluids such as sap. Once they reach their destination, they interact with specific cell receptors to trigger a series of biochemical reactions. This process can activate or inhibit certain cellular functions depending on the context and the needs of the plant. For example, a hormone may stimulate root growth at a given time, or induce the closure of stomata to conserve water during a drought. In essence, plant hormones are the internal messengers that allow the plant to make “smart” decisions about how to grow and survive.

What are the main hormones in cannabis plants?

Plants, including cannabis, have an extraordinarily complex hormone system where six main classes of hormones (although there are also others) work together as a perfectly synchronised orchestra, each playing a unique but interconnected role.

If auxins can be compared to the conductor’s baton that sets the rhythm and guides the other instruments, the other hormones are the musicians who perform different parts of this natural symphony. And to understand how we can help our plants reach their full potential, we need to explore the role each one plays.

1. Auxins: the architects of growth

Auxins are perhaps the most well-known plant hormones, and rightly so. They are responsible for directing cell growth and elongation, which is essential to the formation of stems and roots, making them the “architects” of the plant structure.

An interesting feature of auxins is their role in apical dominance, a phenomenon whereby the main stem of the plant inhibits the growth of lateral shoots. This explains why an unpruned plant tends to grow vertically and develop a higher structure with fewer branches. However, when we perform training techniques such as topping, we remove that dominant tip and reduce the concentration of auxins in that area, which allows the lateral shoots to develop with greater strength.

Auxins also play a key role in phototropism. Have you ever noticed how your cannabis plant seems to lean towards the light source on a sunny windowsill? Auxins are responsible for that movement. They are also crucial for rooting, which is why many products for cuttings contain synthetic auxins to stimulate root growth.

2. Gibberellins: the drivers of stretching

Gibberellins are another fundamental class of plant hormones that play a key role in vertical growth and seed germination. They are responsible for the famous “stretching” that plants experience when they enter the flowering phase.

When we change the photoperiod to induce the preflowering, gibberellins are activated, causing rapid growth in height. This is especially evident in sativa varieties, which can be both a blessing and a challenge for growers, depending on the space available for cultivation.

These hormones also participate in the seed germination process by breaking the seeds’ dormancy and activating metabolic processes which are essential for them to start growing. If you’ve ever had problems with seeds that don’t germinate properly (don’t wait a minute longer to get hold of our Sproutly smart germinator!), a gibberellin deficiency may be involved.

3. Cytokinins: the masters of cell division

Cytokinins are another fascinating group of hormones that work hand in hand with auxins to regulate plant development. While auxins promote both vertical and root growth, cytokinins are primarily responsible for stimulating cell division and promoting the development of lateral shoots. Therefore, they are essential for the creation of more leafy and compact plants, which is something that is highly desired by growers looking to maximise their yield when growing in small spaces.

In addition, these hormones have an anti-aging effect on the leaves as they delay their senescence, which helps to keep the plant green and healthy for longer. Some studies even suggest that cytokinins may positively influence trichome production, potentially increasing levels of cannabinoids such as THC or CBD.

4. Abscisic acid (ABA): the guardian of stress

Abscisic acid (ABA) is a lesser known but equally important hormone for cannabis, as its main function is to help the plant respond to environmental stress such as drought or extreme temperatures. One of its most notable actions is to induce the closure of the stomata (i.e., the small pores in the leaves) when the plant detects a lack of moisture, which reduces water loss via transpiration and allows the plant to retain vital resources during adverse conditions.

Furthermore, ABA also regulates processes such as seed ripening and dormancy, ensuring that seeds only germinate when the conditions are optimal. For growers seeking to stimulate responses to stress to improve the production of trichomes or terpenes (which occurs with techniques such as controlled water deficit), this hormone plays a central role.

5. Ethylene: the messenger of ripening

Ethylene is a gaseous hormone that acts as a chemical messenger and has a direct impact on processes such as ripening and senescence. In the case of cannabis, its influence is especially noticeable during the last stages of the plant’s life cycle, where it helps to accelerate the final ripening of the buds by promoting physiological changes in the trichomes and bracts.

This hormone is also related to the natural fall of leaves during late flowering, which can facilitate tasks such as the drying and curing of the buds after harvest. Some growers believe that it could even influence the final terpene and cannabinoid profile by stimulating certain metabolic processes during the ripening.

6. Brassinosteroids: the reproductive enhancers

And last but not least, there’s brassinosteroids, which have a direct and crucial relationship with the growth of cannabis plants. These are plant steroid hormones that act as key regulators in processes related to cell division, tissue elongation, and stress resistance. And although they are not mentioned as often as other plant hormones, their role is crucial in several aspects of the reproductive process.

For instance, brassinosteroids promote the development and differentiation of flower structures, which can translate into better bud formation and an increase in the number of flowers per plant. They also play a crucial role in the ripening of pollen in male plants, which is essential for the sexual reproduction of cannabis. And once fertilisation occurs, they actively participate in the development and ripening of seeds.

Remember: Cannabis hormones are your friends too!

Understanding how these six major plant hormones work opens a fascinating window into the internal processes of cannabis and enables us to work better with our plants to optimise their yield. This knowledge can make a big difference in our grows, from adjusting techniques like pruning or controlled stress to selecting specific products to stimulate certain hormonal responses.

So, if you’ve ever wondered what makes your plant grow so vigorously or produce those resin-filled trichomes that we value so much, you now know that behind it all is an entire hormonal system working tirelessly to make this green miracle called cannabis become a reality.