While the rise of methods like hydroponics and aeroponics have helped to commercialize cannabis cultivation at scale, growing the plant in living soil is another approach that’s gaining traction. This method of cannabis cultivation is focused on mirroring nature to take advantage of the way plants and microbes in the soil have evolved to live side by side in a complementary relationship. The result is healthier and more resilient organically grown plants that produce high-quality flower in bigger yields.
This guide explains what living soil is and why it’s becoming so popular among cannabis cultivators. This guide also covers steps for creating your own living soil and tips for making the most of this powerful growing medium.
What is Living Soil?
Living soil is a growing medium that contains healthy microorganisms, including fungi, bacteria, protozoa, arthropods and nematodes. These microorganisms decompose dead materials in the soil, convert them to nutrients the plant needs (like nitrogen), and distribute them throughout the soil. This makes it easier for the plant's root system to absorb the nutrients.
In turn, the microorganisms feed off of the carbon and sugars released through the plant's root system as a byproduct of its photosynthesis. This symbiotic relationship is called “nutrient cycling,” a sort of mutually-beneficial exchange between plants and microbes.
Benefits of Living Soil for Cannabis Cultivation
Living soil provides an ecosystem that supports the growth of healthier plants with higher yields and better flower in perpetuity. For cannabis cultivators, growing with living soil leverages the power of nutrient cycling to save money and grow healthier plants.
- Improved Nutrient Absorption: Living soil supports the growth of healthier tap and feeder roots, enabling the plant to absorb nutrients more efficiently. Nutrient cycling also means a cannabis plant in living soil does not need synthetic fertilizers and nutrients, removing a significant expense for cultivators.
- Healthier Plants: Plants in living soil are more resistant to pathogens, reducing the risk that disease takes hold and ruins a grow. Additionally, plants in living soil can more effectively ward off pests, eliminating the need to purchase pesticides. This is particularly advantageous in states where the use of pesticides is banned.
- Higher Quality Flower: Cannabis plants in living soil produce flower with higher levels of cannabinoids and terpenes. More potent flower with diverse cannabinoid and terpene profiles could help drive consumer satisfaction and sales revenue while establishing a brand reputation for quality.
- Reduced Water Consumption: Growing cannabis in living soil requires less water, as living soil retains more moisture and makes for more efficient feeding. Less watering improves aeration, reduces erosion, conserves natural resources, and reduces the chances of root rot and mold.
- Eliminates Flushing Pre-harvest: There is no need to flush living soil before harvesting a plant because there are no synthetic fertilizers or nutrients present in it. Eliminating this step saves time, money, and reduces last-minute stress on the plant.
The end result of successfully growing cannabis with living soil is reduced waste, higher quality cannabis, and improved profit margins. But successfully growing with living soil means building it from the ground up and preserving the ecosystem once it is established.
How to Make a Living Soil
To build a living soil, follow these three steps.
Create a Base
There are many ingredients you could combine to create a base for your living soil. Some popular options include peat, compost, coco coir, manure, worm castings, and perlite. The precise mix may vary depending on the needs of the cultivar and the conditions in the growing environment.
The base of your living soil is the foundation upon which an entire ecosystem will be built, so think carefully about the ingredients you’ll use and the proportions in which you will combine them. This recipe from Bustling Nest is a good example of what to expect when creating your base:
- ⅓ part sphagnum peat moss
- ⅓ part perlite
- ⅓ part compost and/or worm castings
In this recipe, the perlite serves to aerate the peat moss, while the worm castings offer the initial dead material needed for microorganisms to feed on and begin reproducing. This base is, at minimum, what you’ll need to build a living soil, but there are more ingredients you could choose to add based on your needs. These ingredients are called amendments.
Amend Your Soil
Amendments can be used to help the microbial life in your base flourish into the thriving ecosystem characteristic of living soil. Common amendments include wood ash, green manure, and kelp meal. These amendments are used to adjust pH levels and introduce important elements into the soil to support life.
For example, kelp meal is used to introduce nitrogen, potassium, and phosphorus to the soil, all things a plant needs to grow. In addition, it introduces calcium, zinc, manganese, iron, sulfur, copper, and magnesium, which supports a healthy ecosystem for microbials. Adding the right amendments to your soil means regularly testing and observing the progress your base is making over time.
“Cook” Your Soil
Once you’ve combined your base and amendments, gently stirring them until they’re evenly mixed together, it’s time to let your soil “cook.” Leave the soil alone for two to four weeks so the microbes can begin to feed on the organic matter in the soil and reproduce. Once these colonies take hold throughout the soil, you’ve got a living soil that is ready to nourish a young healthy plant into maturity.
When working with living soil, it’s important to understand the ecology behind how microorganisms and plants coexist. In addition to the steps above, begin with some basic research into the types of microorganisms that comprise a living soil and how their life cycle relates to a cannabis plant.
Three Tips for Growing Cannabis with Living Soil
If you want to get the most out of your grow with living soil, these three tips can improve your results.
Start with Healthy Plants
Sticking a weak or diseased plant in living soil is not going to produce the same results as starting with a healthy, vigorous plant. Some plants may also bring along a pest problem, which is not ideal for starting off on the right foot.
To avoid these problems, the best option is to cut a clone from a thriving mother plant. If that’s not available, then consider starting from seed. However, if your plant develops a pest problem, there are a few things you could do, such as add diatomaceous earth to your living soil. This amendment is made of fossilized organisms that act as a natural pesticide.
Optimize Environmental Conditions
Ensuring your plants are growing in the optimal conditions is key to realizing the best possible results with living soil (or any cultivation method, really). Temperature, humidity, CO2 levels, vapor-pressure deficit (VPD), and airflow all play a major role in a plant’s development. Monitoring and responding to these conditions with environmental monitoring software is critical, especially one that provides real-time alerts and notifications when conditions change.
With TSRgrow’s GROWHub platform, your environmental monitoring software is connected through your LED grow lights. This offers you a panoramic view of everything that happens in your cultivation facility. GROWHub can also archive conditions over time, so you can analyze what works best for your plants and plan for future grows.
Develop Cultivar-Specific Master Recipes
Giving your plants exactly what they need is the key to big yields and top-quality flower, so it’s important to know exactly what each cultivar wants. To do this, you should develop a master recipe that includes a cultivar’s preferred conditions and nutrient requirements. Then, you should work to build individualized living soil that provides each cultivar with precisely what it needs to flourish.
GROWHub offers cultivators the ability to create, save, and modify master recipes by cultivar, giving all personnel a roadmap to success directly available within the system. Over time, as more data is captured, these master recipes can be optimized to further improve results. This information could also be used to develop a living soil specifically tailored to the needs of the plant.
A Back-to-the-Land Approach to Cannabis Cultivation
Growing with living soil isn’t just a cultivation method, it’s Mother Nature in action. Cultivators who work with living soil are harnessing the power of evolution and the mutually beneficial relationship between plants and microorganisms. Rather than just cultivating cannabis, living soil growers are cultivating an ecosystem that can support healthy plants, booming growth, and stronger profit margins. Coupling that ecosystem with TSRgrow’s LED grow light platform and GROWHub environmental monitoring solution is a recipe for cultivation success.
