Living soil has become a favored option for cannabis cultivators who want to eliminate the need for pesticides and fertilizers. The active, diverse environment typically requires that a cultivator source organic materials to foster a range of microbial organisms. Forms of life too small to be seen with the naked eye may include bacteria, nematodes, amoebas, protozoans, and worms all make up this thriving growing medium.
Brie Kralick, director of cultivation for Hava Companies, LLC, in Carbondale, Colorado, said living soil is typically rich in nutrients.
Ensuring the soil stays healthy requires paying attention to the cannabis plants, cover plants, and companion plants. It is also important to get a sense of the feel and nature of the soil.
“We try to maintain the population of organisms to be optimal for the microbes to help feed our plants. The idea is that they form a soil food web that feeds the plants. In return, the plants give them carbons and sugars,” says Kralick.
Kralick said the microbes respond to what the plants communicate. This results in high-quality, clean cannabis.
“We start with fresh, loamy soil. Then we add kelp, bat guano, alfalfa meal, helic acid, azomite, or rock dust, dolomite, a form of limestone, and lime, made from ground limestone rock.
liquid extracts made by steeping compost in water,” says Kralick.
Cannabis grown in living soil is known to have a true potency and a smooth pull when smoked. Its natural ingredients and green practices are also better for the environment, something more cannabis consumers are looking for in their products.
Joe Wilson, a salesperson for New Moon Cultivation, a cannabis cultivator in Norman, Oklahoma, agrees living soil makes a notable difference in the smell and flavors that cannabis produces.
“The terpene profiles of plants grown in living soil are more aromatic and flavorful. I have noticed that plants grown in living soil have consistently strong profiles,” says Wilson.
Understanding Where Cannabis Fits In
According to Nick Tomasini, founder of Humankind Oregon, LLC, “living” is the typical state of soil in nature. A cohort of microorganisms acts to decompose leaf litter, detritus, and cycle nutrients.
Humankind Oregon, a Portland, Oregon-based company, assists cannabis cultivators by performing soil biology testing and analysis.
Tomasini says researchers are just beginning to understand the intricacies of how soil microbiomes vary between ecosystems. Soil microbiomes are communities of microorganisms in the soil that are associated with plants, animals, and insects.
“The microbiome of a weedy dirt lot has a lot more bacteria than the soil in a climax forest. That is a forest that has existed for centuries and is relatively stable. The climax forest will have far more fungi,” says Tomasini.
He adds cannabis likely developed as a late succession plant or a plant that replaces other plants in an ecosystem, somewhere between grassland and forest ecosystems. The origins of cannabis are still somewhat unknown, though we do know people began to breed different varieties of cannabis in agricultural settings 500 to 600 years ago.
“Today, cannabis thrives in many environments. That’s why I am able to help cannabis cultivators across six different states: Oregon, Washington, California, Montana, New Mexico, and Oklahoma,” says Tomasini.
An Upfront Cost, but Long-Term Benefits
Building living soil from scratch takes effort and investment. “Some people get sticker shock when they buy living soil. You need to remember that you will reuse the soil over and over. If you get into 20 or 30 cycles, the cost starts to become negligible,” says Chris Brady, co-owner of Redbud Soil Company in Oklahoma City, Oklahoma.
Brady, who has been making soil for more than 10 years, says living soil is forgiving of cultivators who make mistakes.
“There’s a lot of buffer to it. That helps new growers with the learning curve.”
Brady notes Redbud is constantly fine-tuning its composting process.
“We always want to elevate the microbial count in our compost. That’s why we experiment with different ingredients that are available to us,” he says.
Redbud currently uses a large amount of pine-bark wood chips obtained from local lumber companies.
“Anything from a forest brings that fungal component into a compost. We already have a high bacterial count from other types of inputs that we source,” he says, adding cultivators should have their living soil tested every so often to check for concerns.
“When rotifers, multicellular aquatic animals, and ciliates, protozoans with hair-like structures, start to pop up, that means you have anaerobic pockets in the soil. This means water may be pooling. Alternatively, the ground can have spots lacking in oxygen. Both situations can kill living soil.”
A.J. Flad, co-founder of Growing Organic, an apothecary and cultivation supply shop in Delta, Colorado, says living soil works best in outdoor grows.
“You can put living soil in 3- or 5-gallon pots, but you’ll have a very difficult time maintaining it unless you keep the plants small. Living soil needs a lot of room. It usually does best in a 15-gallon pot inside at a minimum. A 30-gallon pot is optimal. If you want monster plants outdoors, spring for 300-gallon fabric pots,” says Flad, adding a cultivator can use native soil as a base for living soil.
“Start by doing a basic soil test if using native soil. You can add living soil that you buy or ingredients you purchased to achieve a balanced soil based on the test,” he says, noting “there’s no magic bullet” in organic cultivation. “Having things in balance is key. This also goes for the range of nutrients that living soils make available. When you have a wide range of nutrients, you see cannabis plants exhibit vastly different expressions of terpene profiles. Usually, that’s preferable to growing a set of plants with very similar terpene profiles.”
Maintaining Living Soil
COVID-19 has caused global supply chain disruptions, including a shortage of peat moss. The problems have led to delays and staffing shortages for living soil creators. Yet companies like Hava Gardens are excited that consumers and cultivators are beginning to understand the benefits of their products.
“We reduce the carbon footprint by recycling soil. Living soil also doesn’t require as much raw material as fertilizer or synthetics. In addition, living soils reduce waste. Customers do not have to drive to stores and dispose of large plastic buckets on a regular basis,” says Kralick.
Brady adds certain cultivation tools, like a tensiometer, to optimize growth with living soil.
“A tensiometer gauges the water tension in the soil. This lets you know whether you’re overwatering or underwatering your plants. When you water plants in living soil properly, you won’t need expensive additives such as plant growth regulators (PGRs) to accelerate growth. You’ll know ingredients are working if you send a lab leaf sample for a sap test or soil samples for a soil test.”
A soil test determines the number of water-soluble elements like potassium and trace elements like copper in the soil.
Genomic analysis is another valuable tool.
With high-level microscopy analysis (use of a microscope to perform analysis), a soil analyst can determine the biomass, the total mass of organisms in a given area, and the basic functionality of a living soil's microbiome. Living soil may contain beneficial fungi and harmful oomycetes, fungus-like water molds.
“We can quantify the biomass levels of each to ascertain whether the former is greater than the latter. The cultivator can then use the findings to calibrate their approach,” says Tomasini.
He added that analysts can use a genomic assessment of soil microbiomes to give a clearer picture of the types of species in living soil. The genomic assessment may also reveal if and why the soil helps the cannabis to remain healthy. This is because the assessment identifies how the species present benefit the cannabis plants.
No-till beds of living soil or native soil mixed with living soil tend to yield the best results in an indoor or controlled greenhouse setting. Growers are encouraged to utilize their native soils whenever possible, especially in full-term outdoor and light-deprivation greenhouse production. “These setups help all the plants share resources well. Be patient,” says Tomasini. “The network takes time to develop. Fungi, which provide plants with phosphorus and other essential elements, are extremely beneficial. They take the longest time to set up.”