Controlling your grow environment doesn’t start when you germinate your first seeds, it starts before you build your grow. There are steps you can take that will have a significant impact on mold growth and contamination, and these will vary based on the grow environment you choose.
Below is a roadmap to where each grow environment stands in terms of mold and contamination risk, and simple steps you can take to mitigate these factors.
The benefits of an outdoor grow are significant – using natural sunlight to grow plants is both inexpensive and environmentally sound. However, it allows the least amount of control and makes plants susceptible to weather conditions and outdoor contaminants including dust, wind, rain and insects. Depending on humidity and precipitation levels, mold can be a big issue as well.
When selecting an outdoor area for a cannabis farm, there are two important factors to consider: location and neighboring farmland. Geographical environments and sub-climates vary and once you have purchased land, you are committed, so be sure to consider these factors prior to purchase.
While arid desert climates have abundant sunlight and long growing seasons, flat, dry lands are subject to dust-storms, flash floods and exceedingly high winds that can damage crops. Conversely, more protected areas often have high humidity and rainfall late in the season, which can create huge issues with bud rot and mold. Neighboring farms also have an impact on your grow, so be sure to find out what they cultivate, what they spray, their harvest schedule and how they run their operation. Large farming equipment kicks up a lot of contaminant-laden dust and can damage crops by displacing insects to your farm if they harvest before you. Pesticide drift is also a major issue as even tiny amounts from a neighbor’s farm can cause your crops to fail testing, depending on what state you are in.
With outdoor grow environments always at the mercy of Mother Nature, any cultivator is wise to control contamination potential on the ground. Cover soil and protect your crop by planting cover crops and laying plastic mulch on as much ground as reasonable. In many cases it makes sense to irrigate uncultivated parts of your farm just to keep dust down.
Greenhouses are the future of cannabis cultivation. They allow growers to capture the full spectrum and power of the sun while lessening environmental impact and operating expenses, while still being able to precisely control the environment to grow great cannabis. With recent advancements in greenhouse technology such as automated control systems, positive pressure, geothermal heating or cooling and LED supplemental lighting, greenhouses are the future. However, older or economy greenhouses that take in unfiltered air from outside still have a medium amount of mold and contamination risk.
Before building your greenhouse, study the area while taking into account climate, weather conditions and sun exposure. Excessively windy areas can blow in contaminants, and extremely hot climates make cooling the greenhouse interior a challenging and costly endeavor.
There are several simple operational tactics to reduce contaminants in a greenhouse. Add a thrip screen to keep insects out, thoroughly clean pad walls with an oxidizing agent after each cycle, and keep plants at least 10 feet from pad walls. Plan to flip the entire greenhouse at once so that you can clean the greenhouse top to bottom before your next crop. A continuous harvest in your greenhouse allows contaminants to jump from one plant to the next and reduces the ability to control your environment and eliminate problems at the end of a cycle. Lastly, open shade curtains slowly in the morning. This prevents temperature inversion and condensation, which can cause water drops to fall from the ceiling and transfer contaminants onto plants below.
An indoor environment offers ultimate control to any grow operation. Cultivators can grow high-quality cannabis with the smallest potential for yeast and mold growth. Unfortunately, indoor environments are extremely expensive, inefficient and environmentally costly.
With indoor grow environments, keeping mold and contaminants at bay comes down to following a regimented plan that keeps all grow aspects clean and in order. To keep your grow environment clean, change HVAC filters multiple times a month. It’s also important to install HEPA filters and UV lights in HVAC systems to further reduce contamination threats. Clearly mark air returns if they are near the ground and keep those areas free of clutter. They are the lungs of your grow. Also, stop using brooms in the grow space. They stir up a lot of contaminants that have settled to the floor. Instead, use HEPA filter backpack vacuums or install a central vacuum system. Set up a “dirty room” for anything messy on a separate HVAC system, and be sure to thoroughly clean pots after every harvest cycle.
It is that time of year where the holidays afford us an opportunity for rest, recuperation and introspection. Becoming a new father to a healthy baby girl and having the privilege to make a living as a scientist, fills me with an immeasurable sense of appreciation and indebtedness. I’ve also been extremely fortunate this year to spend significant time with world-renowned cannabis experts, such as Christian West, Adam Jacques and Elton Prince, whom have shared with me a tremendous wealth of their knowledge about cannabis cultivation and the development of unique cannabis genetics. Neither of these gentlemen have formal scientific training in plant genetics; however, through decades of experimentation, observation and implementation, they’ve very elegantly used alchemy and the principles of Mendelian genetics to push the boundaries of cannabis genetics, ultimately modulating the expression of specific cannabinoids and terpenes. Hearing of their successes (and failures) has triggered significant wonderment and curiosity with respect to what can be done beyond the genetic level to keep pushing the equilibrium in this new frontier of medicine.
Lighting conditions can greatly impact the expression of terpenes (and cannabinoids) in cannabis.Of course genetics are the foundation for the production of premium cannabis. Without the proper genetic code, one cannot expect the cannabis plant to express the target constituents of interest. However, what happens when you have an elite genetic code, the holy grail of cannabis nucleotides if you will, and yet your plant does not produce the therapeutic compounds that you want and/or that are reflective of that elite genetic code? This ‘loss in translation’ can be explained by transcriptomics, and more specifically, epigenetics. In order for the genetic code (DNA) to be expressed as a gene product (RNA), it must be transcribed, a process that is modulated by epigenetic processes like DNA methylation and histone modification. In other words, the methylation of the genetic code can dictate whether or not a particular segment of DNA is transcribed into RNA, and ultimately expressed in the plant. To put this into context, if the DNA code for the enzyme THCA synthase is epigenetically silenced, then no THCA synthase is produced, your cannabis cannot convert CBGA into THCA, and now you have hemp that is devoid of THC.So what is the best lighting technology to enhance the expression of terpenes?
With all of that being said, how do we ensure that our plants thrive under favorable epigenetic conditions? The answer is the environment; and the expression of terpenes is an ideal indicator of favorable environmental conditions. While amazing anti-inflammatories, anti-oxidants and metabolic regulators for humans, terpenes are also extremely powerful anti-microbial agents that act as a robust a line of defense for the plant against bacteria and pests. So, if the threat of microbes can induce the expression of terpenes, then what about other environmental factors? I am of the opinion that the combination of increased exposure to bacteria and natural sunlight enhances the expression of terpenes in outdoor-grown cannabis compared to indoor-grown cannabis. This is strictly my opinion based off of my own qualitative observations, but the point being is that lighting conditions can greatly impact the expression of terpenes (and cannabinoids) in cannabis.
So what is the best lighting technology to enhance the expression of terpenes? Do I use full spectrum lighting or specific frequencies? The answer to these questions is that we don’t fully know at this point. Thanks to the McCree curve we have a fundamental understanding of the various frequencies within the visible light spectrum (400-700nm) that are beneficial to plants, also known as Photosynthetically Active Radiation (PAR). However, little-to-no research has been conducted to determine the impacts that the rest of the electromagnetic spectrum (also categorized as ‘light’) may have on plants. As such, we do not know with 100% certainty what frequencies should be applied, and at what times in the growth cycle, to completely optimize terpene concentrations. This is not to disparage the lighting professionals out there that have significant expertise in this field; however, I’m calling for the execution of peer-reviewed experiments that would transcend the boundaries of company white papers and anecdotal claims. In my opinion, this lack of environmental data provides a real opportunity for the cannabis industry to initiate the required collaborations between cannabis geneticists, technology companies and environmental scientists. This is one field of research that I wish to pursue with tenacity and I also welcome other interested parties to join me in this data quest. Together we can better understand the environmental factors, such as lighting, that are acting as the molecular light switches at the interface of genetics and transcriptomics in cannabis.
Editor’s note: This article should serve as a foundation of knowledge for yeast and mold in cannabis. Beginning in January 2018, we will publish a series of articles focused entirely on yeast and mold, discussing topics such as TYMC testing, preventing yeast and mold in cultivation and treatment methods to reduce yeast and mold.
Cannabis stakeholders, including cultivators, extractors, brokers, distributors and consumers, have been active in the shadows for decades. With the legalization of recreational adult use in several states, and more on the way, safety of the distributed product is one of the main concerns for regulators and the public. Currently, Colorado1, Nevada and Canada2 require total yeast and mold count (TYMC) compliance testing to evaluate whether or not cannabis is safe for human consumption. As the cannabis industry matures, it is likely that TYMC or other stringent testing for yeast and mold will be adopted in the increasingly regulated medical and recreational markets.
The goal of this article is to provide general information on yeast and mold, and to explain why TYMC is an important indicator in determining cannabis safety.
Yeast & Mold
Yeast and mold are members of the fungi family. Fungus, widespread in nature, can be found in the air, water, soil, vegetation and in decaying matter. The types of fungus found in different geographic regions vary based upon humidity, soil and other environmental conditions. In general, fungi can grow in a wide range of pH environments and temperatures, and can survive in harsh conditions that bacteria cannot. They are not able to produce their own food like plants, and survive by breaking down material from their surroundings into nutrients. Mold cannot thrive in an environment with limited oxygen, while yeast is able to grow with or without oxygen. Most molds, if grown for a long enough period, can be detected visually, while yeast growth is usually detected by off-flavor and fermentation.
Due to their versatility, it is rare to find a place or surface that is naturally free of fungi or their spores. Damp conditions, poor air quality and darker areas are inviting environments for yeast and mold growth.
Cannabis plants are grown in both indoor and outdoor conditions. Plants grown outdoors are exposed to wider ranges and larger populations of fungal species compared to indoor plants. However, factors such as improper watering, the type of soil and fertilizer and poor air circulation can all increase the chance of mold growth in indoor environments. Moreover, secondary contamination is a prevalent risk from human handling during harvest and trimming for both indoor and outdoor-grown cannabis. If humidity and temperature levels of drying and curing rooms are not carefully controlled, the final product could also easily develop fungi or their growth by-product.
What is TYMC?
TYMC, or total yeast and mold count, is the number of colony forming units present per gram of product (CFU/g). A colony forming unit is the scientific means of counting and reporting the population of live bacteria or yeast and mold in a product. To determine the count, the cannabis sample is plated on a petri dish which is then incubated at a specific temperature for three to five days. During this time, the yeast and mold present will grow and reproduce. Each colony, which represents an individual or a group of yeast and mold, produces one spot on the petri dish. Each spot is considered one colony forming unit.
Why is TYMC Measured?
TYMC is an indicator of the overall cleanliness of the product’s life cycle: growing environment, processing conditions, material handling and storage facilities. Mold by itself is not considered “bad,” but having a high mold count, as measured by TYMC, is alarming and could be detrimental to both consumers and cultivators.
The vast majority of mold and yeast present in the environment are indeed harmless, and even useful to humans. Some fungi are used commercially in production of fermented food, industrial alcohol, biodegradation of waste material and the production of antibiotics and enzymes, such as penicillin and proteases. However, certain fungi cause food spoilage and the production of mycotoxin, a fungal growth by-product that is toxic to humans and animals. Humans absorb mycotoxins through inhalation, skin contact and ingestion. Unfortunately, mycotoxins are very stable and withstand both freezing and cooking temperatures. One way to reduce mycotoxin levels in a product is to have a low TYMC.
Yeast and mold have been found to be prevalent in cannabis in both current and previous case studies. In a 2017 UC Davis study, 20 marijuana samples obtained from Northern California dispensaries were found to contain several yeast and mold species, including Cryptococcus, Mucor, Aspergillus fumigatus, Aspergillus niger, and Aspergillus flavus.3 The same results were reported in 1983, when marijuana samples collected from 14 cannabis smokers were analyzed. All of the above mold species in the 2017 study were present in 13 out of 14 marijuana samples.4
Aspergillus species niger, flavus, and fumigatus are known for aflatoxin production, a type of dangerous mycotoxin that can be lethal.5 Once a patient smokes and/or ingests cannabis with mold, the toxins and/or spores can thrive inside the lungs and body.6, 7 There are documented fatalities and complications in immunocompromised patients smoking cannabis with mold, including patients with HIV and other autoimmune diseases, as well as the elderly.8, 9, 10, 11
For this reason, regulations exist to limit the allowable TYMC counts for purposes of protecting consumer safety. At the time of writing this article, the acceptable limit for TYMC in cannabis plant material in Colorado, Nevada and Canada is ≤10,000 CFU/g. Washington state requires a mycotoxin test.12 California is looking into testing for specific Aspergillus species as a part of their requirement. As the cannabis industry continues to grow and advance, it is likely that additional states will adopt some form of TYMC testing into their regulatory testing requirements.
Centre for Disease control and prevention. 2004 Outbreak of Aflatoxin Poisoning – Eastern and central provinces, Kenya, Jan – July 2004. Morbidity and mortality weekly report.. Sep 3, 2004: 53(34): 790-793
Cescon DW, Page AV, Richardson S, Moore MJ, Boerner S, Gold WL. 2008. Invasive pulmonary Aspergillosis associated with marijuana use in a man with colorectal cancer. Diagnosis in Oncology. 26(13): 2214-2215.
Szyper-Kravits M, Lang R, Manor Y, Lahav M. 2001 Early invasive pulmonary aspergillosis in a leukemia patient linked to aspergillus contaminated marijuana smoking. Leukemia Lymphoma 42(6): 1433 – 1437.
Verweii PE, Kerremans JJ, Voss A, F.G. Meis M. 2000. Fungal contamination of Tobacco and Marijuana. JAMA 2000 284(22): 2875.
Ruchlemer R, Amit-Kohn M, Raveh D, Hanus L. 2015. Inhaled medicinal cannabis and the immunocompromised patient. Support Care Cancer. 23(3):819-822.
McPartland JM, Pruitt PL. 1997. Medical Marijuana and its use by the immunocompromised. Alternative Therapies in Health and Medicine. 3 (3): 39-45.
Hamadeh R, Ardehali A, Locksley RM, York MK. 1983. Fatal aspergillosis associated with smoking contaminated marijuana, in a marrow transplant recipient. Chest. 94(2): 432-433.
Maintaining an environment that supports cultivation and keeps plants healthy is not an easy task. In cannabis growing, there are a variety of factors that greenhouse managers and personnel must monitor to ensure that their plants are in a healthy environment that fosters growth and development. Temperature, humidity, lighting and CO2 levels are a few of the conditions that need to be tailored to each cannabis greenhouse operation. However, it can be difficult to constantly monitor the status of your equipment and the greenhouse environment, especially after hours or during the off-season.
A remote monitoring system that’s properly selected and installed can help greenhouse managers keep their cannabis plants healthy, multiply their yields and increase return on investment. This type of system also helps operators identify patterns and trends in environmental conditions and get insight into larger issues that can prevent problems before they arise.
Here are some tips on key conditions to monitor and what you need to consider when selecting a monitoring system for your cannabis greenhouse operation:
Temperature plays a crucial role in any cannabis grow operation. The climate in your greenhouse must be warm enough to nurture photosynthesis and the growth of cannabis plants. Setting the incorrect temperature will significantly impact the potential yield of the plant and the rate at which it develops. A temperature too low will slow the growth of the cannabis, but too hot can lead to heat stress for your plants. The ideal temperature for a standard greenhouse is between 70 and 80 degrees Fahrenheit. However, depending on the stage of plant and desired growth densities, the temperature of the greenhouse needs to be adjusted accordingly.
Humidity directly affects plant photosynthesis and transpiration, so controlling humidity is vital in greenhouse growing. The ideal relative humidity (RH) for cannabis growth is around 60%. A low humidity level can cause water to evaporate too quickly for photosynthesis, while a humidity level that is too high can cause poor growth and possible mold and fungal disease. Monitoring the moisture content in the air of your greenhouse will help the plants during the transpiration process, increasing absorption of nutrients and overall health of the cannabis.
Your cannabis may be getting an abundance of natural light during the summer months, but maintaining adequate sunlight during the winter months can be a challenge. As a solution to this, many greenhouse managers equip their facilities with additional lights to supplement natural light during off-seasons or off-hours. To achieve the best possible yield, a cannabis plant in the budding stage should receive twelve hours of light each day, while other stages could require additional lighting. For example, the growth stage could require your cannabis to be exposed to sunlight for up to eighteen hours a day.
Like any other plant, cannabis requires CO2 to breathe. Greenhouse managers must set and monitor the CO2 levels in their facility to make sure that there is an adequate amount for the plants to develop, grow and be healthy. The amount of carbon dioxide required for your cannabis depends of the size of the facility and the amount of light the plants are receiving. However, a standard grow area for cannabis can maintain a CO2 range from 1000 to 1500 parts per million (PPM). A level below that threshold can result in slower growth of the plants, while a level above would lead to unused and wasted CO2.
Irrigation and Soil Moisture
One way to ensure a good yield from your cannabis is to water it regularly and monitor your soil moisture. Overwatering your plants can have the same effect, if not worse, than letting the soil become too dry. Plants’ roots need oxygen to survive, unlike leaves that breathe CO2, and when the soil is waterlogged the roots can’t provide their function. The lack of oxygen interferes with the roots’ nutrient uptake and photosynthesis causing the cannabis plant to wilt. The exact moisture content of the soil depends on the size of your greenhouse, temperature and humidity. Whether you hand water or are using a drip irrigation system, being aware of your soil moisture is vital to the long-term health of your cannabis.
Your greenhouse environment should mimic the ideal conditions in which cannabis plants flourish. With an indoor facility, you have the ability to control air circulation by venting hot air out and blowing fresh air in. Creating a circulation of air inside your greenhouse will increase your cannabis plant’s growth speed and yield. Additionally, an exhaust system helps control the temperature and humidity, while also preventing the invasion of mold and pests that thrive in hot, stagnant air.
When growing something of value, like cannabis, there will always be a threat of intruders. Whether your greenhouse is in a populated area or around hungry wildlife, any intruder could be detrimental to your overall yields and profit. Remote monitoring systems can give you peace of mind and instantly alert you when there is an unwanted presence in your greenhouse.
Knowing all the possible threats to your cannabis greenhouse helps you evaluate your specific needs, and ultimately identify the proper remote monitoring system.
Selecting the Right Monitoring System
Other factors to consider when choosing a monitoring system right for your operation include:
Base unit and sensors
Wireless or hardwired sensors
Communications to your site (Phone, cellular, Wi-Fi, etc.)
Programming and status checks
Return on investment
Base Units and Sensors
Each condition in your greenhouse that you want to monitor requires its own input on the base unit of the monitoring system. You must match your needs with the number of inputs available. A good fit for a smaller cannabis greenhouse may be a lower-cost, non-expandable monitoring system. However, larger facilities have many monitoring points and more people to alert when there’s a problem. If your cannabis operation is poised for growth, purchasing an expandable system could add value to the initial purchase because you wouldn’t have to replace your entire system in the future.
Your monitoring system should also have an internal rechargeable battery backup to ensure continuous monitoring and alerts in the event of a power outage. It is also recommended to have each base unit in a sheltered enclosure to protect it from moisture, dirt and other hazards.
Placement of sensors is also crucial. For example, temperature sensors in your greenhouse should be placed throughout the facility. They should be next to your thermostat and in the center of your greenhouse, preferably away from direct sunlight.
Wireless or Hardwired Sensors
Remote monitoring systems offer the option to have sensors hardwired directly to the base unit or sensors wirelessly connected. A hardwired monitoring system connects the sensors to the base device with wires. Generally, trenching long distances for wires is time consuming and costly. So alternatively, a wireless system uses built-in radio transmitters to communicate with the base unit. Some monitoring systems can accommodate a combination of hardwired and wireless sensors.
Communications to Your Site
Monitoring devices that use cellular communications must be registered on a wireless network (like Verizon or AT&T) before you can send or receive messages. Because cellular devices perform all communications over a wireless network, it is important that there be sufficient signal strength at the greenhouse. It is a good idea to check the signal quality in the area before purchasing a cellular product. If the cellular network has less than desirable coverage, it is possible to install an external antenna to help increase cellular signal.
When monitoring systems identify a change in status, they immediately send alerts to people on the contact list. If you don’t want all of your personnel to receive notifications at the same time, certain devices can be programmed to send alerts in a tiered fashion. It is important to consider the reach of the communications, so that you’ll be notified regardless of your locations. Multiple communications methods like phone, email and text provide extra assurance that you’ll get the alert. Also, note of the number of people the system can reach and if the system automatically cycles through the contact list until someone responds. Make sure the system allows for flexible scheduling so that it doesn’t send alarms to off-duty personnel.
Programming and Status Check
If you’re responsible for maintaining a commercial greenhouse facility, you want a system that will provide real-time status of all monitored conditions on demand. There are a few different ways to access your sensor readings. Options include calling to check status, viewing a web page, either on a local network or on the cloud, or accessing the information via an app on your mobile device. With a cloud-based system, the devices supervise themselves. This means if the internet or cellular connection goes down, the device will send an alarm to alert the appropriate personnel.
If you don’t select a cloud-based system, you will be limited to logging in through a local area network, which will allow you to make programming changes, access status conditions and review data logs. If internet connectivity is not available at your location, you will want to choose a cellular or phone system rather than Ethernet-based option.
Data history is valuable in identifying patterns and trends in your cannabis greenhouse conditions. Manually monitoring and recording environmental parameters takes a significant amount of personnel time and detracts from other important workplace demands. However, many monitoring systems automatically save information, recording tens of thousands of data points, dates and times. Cloud-based logging provides an unlimited number of records for users to view, graph, print and export data trends.
Analyzing data samples may lend insight to larger issues and prevent problems before they arise. For example, if the data log shows power fluctuations occurring at a regular time, it could be indicative of a more serious problem. Or, if the data shows signs of a ventilation fan or supplementary lighting beginning to malfunction, they can be repaired or replaced before total failure occurs.
Return On Investment
When deciding how much you should pay for a remote monitoring system, tally up the entire cost, fully installed with additional peripherals and sensors and any labor fees for installation. Then consider the value of your cannabis plant inventory and greenhouse equipment. Finally, factor in the cost of downtime, should an environmental event shut down your operation for a period of time.
Choosing the right greenhouse monitoring system and sensors could mean the difference between life and death for your cannabis plants. Understanding the conditions you need to watch and monitoring systems’ capabilities are they best way to protect your investment.
In the first part of this series, we introduced some relevant terms and principles to tissue culture micropropagation and reviewed Dr. Hope Jones’ background in the science of it. In the second part, we went into the advantages and disadvantages of using mother plants to clone and why tissue culture could help growers scale up. In the third part of this series, we are going to examine the five steps that Dr. Jones lays out to successfully micropropagate cannabis plants from tissue cultures.
Cleaning – Stage 0
Micropropagation includes 5 stages. “Stage 0 is the preparation of mother plants and harvest of cuttings for the explant material,” says Dr. Jones. “To ensure the best chance of growing well in culture, those ladies [the mom’s] should be cleaned up and at their best. And hopefully not stressed by insects or pathogens.” She says growers should also make sure the plants are properly fertilized and watered before harvesting explants. “Obtaining the explants is done with a clean technique using new disposable blades and gloves,” says Dr. Jones. “Young shoot tips are harvested and placed in labeled, large Ziploc bags with a small amount of dilute bleach and surfactant solution, then placed in a cooler and taken to the lab.” This is a process that could be documented with record keeping and data logs to ensure the same care is taken for every explant. “Once in the lab, working in the sterile environment of the transfer hood, the cuttings are sterilized, typically with bleach and a little surfactant, and then rinsed several times with sterile water,” says Dr. Jones. Once they reach the sterile environment, Dr. Jones removes the leaves and cuts the stem down to individual nodes.
Establishment – Stage 1
Establishment essentially means waiting for the shoots to develop. Establishing the culture requires an absolutely sterile environment, which is why the first step is so important. “Proper explant disinfection is equally as important is the control parameters of the facility itself,” says Dr. Jones. Mother plants are not grown in sterile facilities, but in an environment that is invariably contaminated with dust, which harbors micro-organisms, insects and other potential sources of contamination, including human handling. We discussed some of this in Part 2.
Explants, once sterilized and placed in the culture vessel, must establish to the new aseptic conditions. “Basically Stage 0 ends when the explants are cleaned and placed in the vessel. Stage 1 begins on the shelf while we patiently sit, watch and wait for the shoot growth,” says Dr. Jones. “Successful establishment means we properly disinfected the explants because the cultures do not become contaminated with bacteria or fungi and new shoot growth emerges.”
Multiplication – Stage 2
This stage is rather self-explanatory as multiplication simplified means generating many more shoots per explant. In order to create a large number of plants needed for meeting the demand of weekly clone orders, Dr. Jones can break up, or subculture, one explant that contains multiple numerous new shoots. “Let’s say one vessel, which originally started with 4 explants each developed four new shoots. Working in the hood, I remove each explant from the vessel and place it on a sterile petri dish. Now I can divide each explant into 4 new explants and then place the four new explant cuttings into their own vessel. In this example, we started with one vessel with 4 explants,” says Dr. Jones. “Which when subcultured 4-6 weeks later, we now have 4 vessels with 16 plants.” This is instrumental in understanding how tissue culture micropropagation can help growers scale without the need for a ton of space and maintenance. From a single explant, you can potentially generate 70,000 plants after 48 weeks, according to Dr. Jones. “Starting with not 1, but 10 or 20 explants would significantly speed up multiplication.” Using tissue culture effectively, one can see how a grower can exponentially increase their production.
Rooting – Stage 3
“When the decision is made to move cultures to the rooting stage, we typically need to subculture the plantlets to a different media formulated to induce rooting,” says Dr. Jones. “In some instances, the media is very dark, and that’s because of the addition of activated charcoal.” Using activated charcoal, according to Dr. Jones, helps darken the rooting environment, which closely mimics a normal rooting environment. “It helps remove high levels of cytokinin and other possible inhibitory compounds,” says Dr. Jones. Cytokinins are a type of plant growth hormone commonly used to promote healthy shoot growth, but it is important to make sure the culture contains the right ratio of hormones, including cytokinin and auxin for maximum root and shoot development. Dr. Jones suggests that growers research their own media formulation to ensure nice, healthy roots develop and that no tissue dies in the process. “With everything I grow in culture, when it comes to media, in any stage and with all new strains, I run some simple experiments in order to refine the media used,” says Dr. Jones. She puts a special focus on the concentrations and ratios of plant hormones in formulating her medias.
“We commonly think of auxin’s role in rooting, but it’s also important in leaves and acts as a regulator of apical shoot dominance,” says Dr. Jones. “So having no auxin may not be ideal for the shooting media used in Stages 1 and 2.” Auxin is a plant hormone that can help promote the elongation of cells, an important step in any plant’s growth. “And cytokinins are typically synthesized in the root and moves through xylem to shoots to regulate mitosis as well as inducing lateral bud branching, so again finding that nice balance between these two hormones is key.”
Acclimation & Hardening Off – Stage 4
“When plants have developed good looking healthy roots, it’s time to pop the top,” says Dr. Jones. This means opening the vessel, another risk for contamination, which is why having a clean environment is so crucial. “The location of these vessels needs to be tightly controlled for light, relative humidity, temperature and cleanliness.” In the culture, sugar is a main ingredient in the medium, because the growing explants are not very photosynthetically active. “By opening the lid of the vessel, carbon dioxide is introduced to the environment, which promotes and enhances photosynthesis, really getting the plants ready for cultivation.”
The very final step in tissue culture micropropagation is hardening, which involves the formation of the waxy cuticle on the leaves of the plant, according to Dr. Jones. This is what preps the plant to actually survive in an unsterile environment. “The rooted plants are removed from the culture vessel, the media washed off and placed in a potting mix/matrix or plug and kept in high humidity and low light,” says Dr. Jones. “Now that there is no sugar, contamination is no longer a threat, and these plants can be moved to the grow facility.” She says conditioning these plants can take one or two weeks. Over that time, growers should gradually increase light intensity and bring down the relative humidity to normal growing conditions.
Overall, this process, if done efficiently, can take roughly eleven weeks from prepping the explants to acclimation and hardening. If growers perform all the steps correctly and with extra care to reduce risks of contamination, one can produce thousands of plants in a matter of weeks.
In the fourth and final part of this series, we are going to dive into implementation. In that piece, we will discuss design principles for tissue culture facilities, equipment and instrumentation and some real-world case studies of tissue culture micropropagation.
As the drought in California persists and quickly becomes the new hydrological norm, many within the state have embraced efforts to find ways and means to live within the drought forced water “budget.” Because of the importance of water conservation, the cannabis industry should embrace its socio-ecological responsibility and seize the opportunity to help shift the perception of cannabis cultivation into that of a sustainable, high-value agricultural crop that can be grown in an environmentally safe manner, while using water efficiently.
The intersection of Prop 64, MCRSA and the drought provides the cannabis industry with a unique opportunity to positively impact water conservation. Because legal cannabis cultivators are just now designing blueprints for grow sites, these cultivators are in a position to build infrastructure and systems specifically designed to achieve permanent, sustainable water conservation.
By embracing and championing water conservation, the cannabis industry will achieve two goals: being a collaborative player in the larger community working towards sustainable water use and enhancing the overall perception of the cannabis industry in the conscious of the general public. For an industry seeking legitimacy, there is no better way to put cannabis in the mainstream conscious than by embracing environmentally responsible philosophies. Here are a few measures the cannabis industry should embrace:
The current drought has generated a state-wide conversation about tracking and recording water usage. Some commentators believe California is suffering from a water data problem. Recently passed AB 1755 is a step by California to address that shortcoming by creating a technology platform to aggregate and share water data. Cannabis cultivators should get onboard with measuring water usage. One method is to install sensitive flow meters in each drip station to precisely measure water used during each grow cycle. First, this provides the cultivator with a precise data set. Precise data sets are extremely important, especially when trying to achieve the two-part-goal of conserving water and maximizing crop yield. Second, having precise data sets allows the cultivator to determine, from harvest-to-harvest, increasingly precise ratios of input (water) to output (flower). Most likely, this input:yield ratio is subject to diminishing returns at the margin; that is, adding additional water will not proportionately increase crop yield. For instance, 50 units of water could produce 50 units of crop, but 75 units of water might only produce 55 units of crop. By measuring the input (water), the cultivator is able to identify the precise threshold where diminishing returns set in and can therefore reduce the “diminishing returns” water usage, saving money and conserving water.
Building on water-usage data collection, cultivators can then collaborate with each other and with water agencies. By sharing data sets, cultivators can quickly develop ideal input:yield ratios, can better understand how water usage fluctuates within each discreet grow cycle and can develop methods such as deficit irrigation and real-time soil moisture measurements. This collective industry knowledge will help each individual cultivator to reduce water-usage. In collaborating with local water boards, the boards will better understand how much water is being used and conserved by the industry. Additionally, if the boards have a more precise understanding of the expected usage per season or per specific period in a grow cycle required by cultivators in their jurisdictions, those boards can better plan for the peaks and troughs in water demand. Besides data sharing, agencies and cultivators can collaborate in developing “fill stations” (offering free, non-potable recycled water for irrigation), or help fund development of direct potable water technologies and other recycled water technologies. Collaboration amongst growers and with water boards will lead to greater water conservation.
An ancillary benefit to water conservation behaviors is the reduction of energy consumption. It takes an immense amount of energy to pump and transport water to end-users, such as cultivators. Reducing water usage in turn reduces energy consumption, because less water used means less water transported and disposed of. This is one method for indoor cultivators to offset energy consumption. In addition to reducing energy usage by conserving water, cultivators can follow Irvine Ranch Water District’s example of implementing an energy storage system to reduce costs and ease energy demand during peak hours. Indoor cultivators should adopt the same basic structure and mechanics: install Tesla battery packs to store energy for use during peak hours (when electricity is more expensive) and recharge the batteries at night when demand is low (and electricity is cheaper).
This is an exciting time in California’s history, with the pending election of Prop 64, the passage of MCRSA, and the opportunities present in the water-energy nexus. The $6 billion cannabis industry has an incredible opportunity to have a far-reaching impact on water-conservation. By being an active collaborator conserving water, the cannabis industry can position itself as a trendsetter and private sector leader in sustainable and eco-conscious methods, technologies, and processes.
The average commercial cannabis cultivator seems to be following the modern agricultural paradigm. That model is based on questionable and, one might say, ineffective soil systems management.
In the high-yield cannabis world, amidst decades of prohibition, following the lead of the modern agricultural model has resulted in the adoption of cultural practices that go something like this: Use and destroy the soil, then dispose of it once it is rendered lifeless and useless due to repeated heavy applications of chemical fertilizers, pesticides, and other poisons.
Certainly conventional agricultural food production and the soil management systems underpinning them are faltering, evidenced by soil systems deteriorating many times faster than they are being improved. This qualifies as a failure in my book.
What will be the fate of profit margins, sustainability and medicine in the cannabis industry if we continue to follow blindly in the footsteps of chemical agriculture? Perhaps it is time to turn over a new leaf.
Well…world agricultural production accounts for about three-quarters of the soil erosion worldwide. This steep decline in arable soil is occurring during a time when the world’s demand for food is rapidly increasing. It is estimated that the world will need to grow 50% more food by 2050, and it is important to note that, the total volume of food necessary, remains relative to the nutrient density of the food.
Time for a radical solution, and cannabis can lead the way.
As the cannabis industry continues to grow, now more than ever we have the opportunity, and I believe the responsibility, to cultivate in ecologically mindful ways, improve the end product and it’s positive impacts, increase both short-term and long-term profits, decrease or eliminate waste and lower the carbon footprint of cannabis cultivation operations.
Most importantly, we have the opportunity to fund, implement and lead the way in research and development of sustainable, medical, phytonutrient-dense crop production methodologies.
Only by implementing more rigorous scientific methods to cannabis cultivation can we hope to provide truly meaningful improvements in and contributions to the fields of agriculture, science, medicine and human health.
While dumpsters of potting soil continue to roll off to the landfill, complex health and human science and the cultivators truly engaged in science will continue to provide meaningful data regarding plant compounds and what factors influence the best outcome for the desired end product.
I am willing to bet that what is best will not be coming from the business models employing antiquated, wasteful and destructive cultivation strategies, and that in due time these models will fade into distant memories.
This is the first in a series of articles, in which we will explore topics related to the pursuit of high yield, phytonutrient-dense “high brix” cannabis production.
The next article will provide a historical and geologic context to the cannabis plant, as viewed from the scope of soil biology and the progression of ecosystems and soil types, and how maximized genetic expression, through maximized soil and plant health influence the production of high quality cannabis.
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