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Top 3 Ways Cultivation Methods Must Change with Regulations

By David Perkins
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There are obvious upsides and downsides to cannabis regulation. Gone are the days when it was a free for all, for outlaws growing in California’s hills, under the limited protections California’s medical cannabis laws provided. While there is no longer the threat of arrest and incarceration, for the most part, there are also a lot of hoops to jump through, and new rules and standards to contend with. This article highlights three areas in which your cultivation plan must necessarily change due to the new regulations.

1. Integrated Pest Management (IPM) is limited

In the new regulated market, products that were once widely used are now no longer allowed. Prior to regulation, in the days of Prop 215, you could spray your plants with just about anything, since there was no testing mandated for the products that were being sold. However, people unfortunately got sick and experienced negative reactions, with products like Eagle 20, which contains mycobutinol, and Avid, which contains bifenthrin. Accordingly, under new regulations there are thankfully much more stringent standards dictating what pesticides can be used. It’s ironic that for most of the “medical marijuana” era in California there were no mandatory testing requirements for the THC content of your cannabis, let alone testing for toxins, including pesticides, molds or heavy metals.

You need to have a very thorough pest management plan to make sure your bug populations are always in check. Given that there are a small number of allowable products for pest control in the regulated market, this can be tricky. You need to be extremely familiar with what is and isn’t allowed in today’s regulations. You must also make sure that someone who is certified to apply pesticides is applying them.

Photo: Michelle Tribe, Flickr

As a word of caution, there have been instances where approved pesticides were found to have old unused chemicals (that are not approved for use) from the manufacturing process in them. They may have only occurred in very small amounts, but they are harmful to humans and there is no lawful way to dispose of them.

Further, the presence of these harmful chemicals can cause your finished product to fail when undergoing mandated testing.

Rather than using risky chemicals, the best solution for (early detected) control of pests is the use of beneficial insects. Although they may not be the best solution for an infestation, predator bugs like Neoseiulus Californicus can efficiently control small populations of spider mites while ladybugs are good to limit aphids. Strategic planning of your IPM is one of the best ways to keep pest levels in check.

2. Plant size and plant count matter more than ever

Despite widespread legalization in the past few years for both the medical and recreational markets in the United States, the black market is still rampant and most cannabis is still being produced illegally in the US and internationally.

Maximizing plant canopy space is essential to a profitable business in today’s market

Generally speaking, in the black market, the less plants you have the better, as high plant counts lead to longer sentences of incarceration. With the passage of prop 215 in 1996, many growers, especially outdoor, started growing their plants as big as they possibly could because most limitations were based on plant counts. Some outdoor growers were able to cultivate plants that yielded over 10 pounds per plant. These days regulations are based on canopy measurements, meaning you can grow as many plants as you want within a defined, limited square footage area. This is where “light deprivation,” a method used to force plants into flowering, becomes favorable as it allows 2-4 harvests per year instead of just one. It is a much more intensive way of growing when you have tens of thousands of plants. While it is easier to plant, cultivate and harvest a larger number of smaller plants, it also requires a much more detailed level of planning and organization.

In order to achieve 4 harvests per year, you must have a well thought out cultivation plan and an all-star staff, but if you are able to accomplish this, you can increase your revenue significantly. Maximizing plant canopy space is essential to a profitable business in today’s market, and to do that will require more detailed planning, better organization and proper crop management.

3. How you grow and what equipment you use

With regulation comes liability for defects or injury. It is essential that all equipment used is approved for its intended use. Traditionally, cannabis was cultivated in secrecy in the black market. This led to many unsafe grow rooms being built by people who did not have the proper skills to be undertaking projects such as converting a garage into a grow room or handling the electrical and plumbing running into them. Accordingly, there were many instances of damages to property or injuries to people because of this. Now that counties and states permit cannabis cultivation facilities, the infrastructure and labor that is done must meet regulated building codes and general safety requirements. It is therefore imperative to know the codes and regulations and hire a professional that does, to ensure you meet the standards in order to avoid potential liability.

Larger scale cultivation requires bigger and more expensive equipment. Cultivation facilities are more likely to have sophisticated equipment, such as chiller systems, that are designed to control the grow room environment. While very efficient, some are not intended to be used specifically for cannabis cultivation, and can therefore be difficult to control and maintain. They perform very specific functions, and when not properly tuned to your conditions, can malfunction by prioritizing dehumidification over cooling. This can be a real challenge in warmer climates when temperatures rise, requiring cooling, but also necessitate removal of moisture from the cultivation space.

Larger scale cultivation requires bigger and more expensive equipment.

On the other hand, there is new technology that can make a huge difference in the success of your cultivation. I recently worked with two different companies that specialize in root zone heating systems. One manufactured equipment for root zone heating and cooling of 10k sq ft raised beds that had never been used in California previously. The other company specialized in root zone heating using radiant floor heat. They both worked as intended to maintain a constant root zone temperature, which increased plant health, and ultimately increased yield.

Many counties require data collection from your cultivation, requiring you to track the amount of water and nutrients used. Therefore, another useful tool you can use to increase efficiency, is data collection software that will allow you to collect different information about the amount of water and nutrients used, as well as specific information about the conditions in your grow medium. You can also record and display temperature and humidity readings in your grow room, in real time remotely through Wi-Fi, that you can then access from your phone or computer from anywhere in the world. This can be a useful tool when documenting information that your county, state or investors may require from you. Further, the ability to collect and analyze data will allow you to identify areas of inefficiency in order to correct and optimize your grow room’s potential. While you can achieve these same goals with simple in-line water meters, keeping track of nutrients and pesticides is not as easy. Data collection in the most basic form, using a pen and paper, can be an inaccurate and an inefficient use of time, and can easily be misplaced or ruined. Therefore, simple data software collection programs are the best solution to make the process simple and hassle free.

While it is nice to have state of the art equipment, if it does not work properly, or cannot be easily maintained, it will not be worth it in the long run and you will never see a return on your investment. Innovation comes with a price; using equipment that is cutting edge can be risky, but on the flip side, when done properly it can give you a big advantage over your competitors.

In switching from the black market to the regulated market, these three areas have proven to be the biggest areas of change and have presented the biggest challenges. It is important you consider these necessary changes, and make a solid plan before you begin your cultivation. This is where a cultivation consultant can help.

10 Ways to Reduce Mold in Your Grow

By Ketch DeGabrielle
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Regardless of whether your grow is indoor or in a greenhouse, mold is a factor that all cultivators must consider.

Photo credit: Steep Hill- a petri dish of mold growth from tested cannabis

After weeks of careful tending, pruning and watering to encourage a strong harvest, all cultivators are looking to sell their crop for the highest market value. A high mold presence, measured through a total yeast and mold count (TYMC), can cause a change of plans by decreasing crop value. But it doesn’t have to.

There are simple steps that any cultivator can take that will greatly eliminate the risk of mold in a grow. Below are some basic best practices to incorporate into your operation to reduce contaminants and mold growth:

  1. Isolate dirty tasks. If you are cleaning pots, filling pots or scrubbing trimming scissors, keep these and other dirty tasks away from grow and process areas. Dirty tasks can contaminate the grow area and encourage mold growth. Set up a “dirty room” that does not share heating, ventilation and air conditioning with clean areas.
  2. Compartmentalize the grow space. Mold can launch spores at speeds up to 55 miles per hour up to eight feet away without any air current. For this reason, if mold growth begins, it can become a huge problem very quickly. Isolate or remove a problem as soon as it is discovered- better to toss a plant than to risk your crop.
  3. No drinks or food allowed. Any drinks or food, with the exception of water, are completely off limits in a grow space. If one of your employees drops a soda on the ground, the sugars in the soda provide food for mold and yeast to grow. You’d be surprised how much damage a capful of soda or the crust of a sandwich can do.
  4. Empty all trash daily. Limiting contaminants in turn limits the potential for issues. This is an easy way to keep your grow clean and sterile.
  5. Axe the brooms. While a broom may seem like the perfect way to clean the floor, it is one of the fastest ways to stir up dirt, dust, spores and contaminants, and spread them everywhere. Replace your brooms with hepa filter backpack vacuums, but be sure that they are always emptied outside at the end of the work day.
  6. No standing water or high humidity. Mold needs water to grow, therefore standing water or high humidity levels gives mold the sustenance to sporulate. Pests also proliferate with water. Remove standing water and keep the humidity level as low as possible without detriment to your plants.
  7. Require coveralls for all employees. Your employee may love his favorite jean jacket, but the odds are that it hasn’t been cleaned in months and is covered with mold spores. Clean clothing for your staff is a must. Provide coveralls that are washed at least once a week if not daily.
  8. Keep things clean. A clean and organized grow area will have a huge impact on mold growth. Clean pots with oxidate, mop floors with oxidate every week, keep the areas in front of air returns clean and clutter-free, and clean floor drains regularly. The entire grow and everything in it should be scrubbed top to bottom after each harvest.
  9. Keep it cool. Keep curing areas cool and storage areas cold where possible. The ideal temperature for a curing area is roughly 60 degrees and under 32 degrees for a storage area. Just like food, the lower the temperature, the better it keeps. High temperature increases all molecular and biological activity, which causes things to deteriorate faster than at cooler temperatures. However, curing temperature is a function of water activity more than anything.
  10. Be Careful With Beneficials. Beneficial insects certainly have their place in the grow environment. However, if you have a problem with mold on only a small percentage of plants, any insect can act as a carrier for spores and exacerbate the problem. By the same token, pests spread mold more effectively than beneficials because they produce rapidly, where beneficials die if there aren’t pests for them to eat. It is best to use beneficials early in the cycle and only when necessary.

Total Yeast & Mold Count: What Cultivators & Business Owners Need to Know

By Parastoo Yaghmaee, PhD
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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

Photo credit: Steep Hill- a petri dish of mold growth from tested cannabis

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. 

Aspergillus species niger
Photo: Carlos de Paz, Flickr

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.

Aspergillus flavus on culture.
Photo: Iqbal Osman, Flickr

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.

References:

  1. https://www.colorado.gov/pacific/sites/default/files/Complete%20Retail%20Marijuana%20Rules%20as%20of%20April%2014%202017.pdf
  2. http://laws-lois.justice.gc.ca/eng/acts/f-27/
  3. https://www.ucdmc.ucdavis.edu/publish/news/newsroom/11791
  4. Kagen SL, Kurup VP, Sohnle PG, Fink JN. 1983. Marijuana smoking and fungal sensitization. Journal of Allergy & Clinical Immunology. 71(4): 389-393.
  5. 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
  6. 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.
  7. 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.
  8. Verweii PE, Kerremans JJ, Voss A, F.G. Meis M. 2000. Fungal contamination of Tobacco and Marijuana. JAMA 2000 284(22): 2875.
  9. Ruchlemer R, Amit-Kohn M, Raveh D, Hanus L. 2015. Inhaled medicinal cannabis and the immunocompromised patient. Support Care Cancer. 23(3):819-822.
  10. McPartland JM, Pruitt PL. 1997. Medical Marijuana and its use by the immunocompromised. Alternative Therapies in Health and Medicine. 3 (3): 39-45.
  11. 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.
  12. http://apps.leg.wa.gov/wac/default.aspx?cite=314-55-102