
This article originally appeared in the September 2018 print issue of Cannabis Business Times. To subscribe, click here.
The North Carolina State University Horticultural Substrates Laboratory opened its doors in the mid-1980s and has since become one of the only laboratories in the world that solely focuses on substrate science to assist growers, retailers and consumers with substrate-related issues and opportunities. Currently, we (Dr. Brian Jackson (director) and Dr. Bill Fonteno (founder)) operate the lab, conducting grower and industry trials, substrate diagnostic testing, soil/substrate certification, graduate student training and course instruction.
In 2018, we received permits to grow and research cannabis (low THC/high CBD), and now we are broadening our research palette to include the needs and opportunities of the ever-growing cannabis industry.

This industry, due to legal hurdles and crippling stigmas, is somewhat deprived of scientific literature on many production practices and issues. Growers and industry professionals rely heavily on personal experience and information from other industries (e.g., floriculture and greenhouse science). Although hands-on experience is an invaluable source of knowledge, having scientific information to fall back on can greatly expedite the learning process for growers, both experienced and inexperienced. A specific area in need of information is that of container substrates.
Overview of Substrates & Soils
Substrates can be composed of organic or inorganic components, or a mixture of both, that create the container environment in which a plant will grow and thrive. Numerous organic and inorganic components have been used in container crop production over the years. One of the most important things to remember is that these materials are not “soil” and cannot (should not) be handled like soil. Unlike mineral soil (field soil) that can be stored anywhere for any length of time and moved with any heavy equipment, soilless components must be handled as little as possible and with care so they maintain their inherent physical structures and properties.
In the “2018 Growing Media Guide” research report published in Cannabis Business Times’ January issue, 73 percent of survey respondents stated that field soil was used in their growing media in some capacity, while 6 percent said it was their sole material for growing their crops. Many discussion points could be addressed in detail regarding the choice to use field soil in container production. While it may be cheap and easily available, it does offer potential barriers, issues and even missed opportunities.
Issues may include the material weight (which could present lifting difficulties for your employees), introduction of weeds or disease if not properly sterilized, challenging irrigation management, variable soil types and lessened root growth (compared to soilless culture). Missed opportunities may include the inability to be “precision growers,” meaning that during a crop production cycle, if there is a need to adjust water or nutrition to the crop quickly to slow or speed up growth, soil does not respond as readily as soilless mixes. One of the marvels of today’s greenhouse and floriculture professionals is their ability to leverage highly technical and precise monitoring and adjusting of crop inputs and environmental parameters that allow them to control plant growth (based on weather conditions, shipping date, size requirements, etc.). One of the main reasons they can do this is because of the engineered soilless substrates they use to grow their crops, which are highly responsive and easily adjusted.
Many questions, misconceptions and unknowns exist regarding the soilless components used in mixes. We caution readers to be careful where they receive their information not only about substrates, but also about all topics related to cannabis production. We highly encourage cultivators to rely on scientific literature whenever possible or consult with professionals whose information comes from science-based research and experience. Among the reasons we encourage this is that we often hear statements such as “perlite is toxic,” “peat is running out,” “coconut coir is local and more sustainable than peat.” (All three of these comments are 100-percent false, by the way.)
When searching information on the internet about a growing topic, I suggest following up your keywords with “PDF” in your search. This will narrow the scope of the information you find to typically more formal, scientific, published, etc., content compared to open forums, small grower or business websites trying to sell something, or online blogs where opinions flow freely, and facts
To read the full article in the September 2018 issue of Cannabis Business Times, click here.
Photos courtesy of NC State.