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Maintaining cannabis quality beyond cultivation

June 11, 2019  By Mari-Len De Guzman

After harvesting, cannabis plants are cut to the stem level, hanged upside down and left to dry for several days to reduce moisture content, preventing the spread of bacteria, yeast and mould.

Producing high quality cannabis products does not begin and end in the growing of the plant – regardless of genetics. It’s possible to lose or degrade the quality by botching the post-harvest processing.

Health Canada’s demand forecast for both recreational and medical cannabis stands at 926,000 kilograms per year. Shortly after adult-use recreational cannabis was legalized in October 2018, widespread supply shortage became increasingly apparent. Licensed producers are ramping up production to increase supply, with some bigger LPs forecasting production capacities for built facilities in the hundreds of thousands of kilograms of dried flower per year.

Shortage of quality cannabis products in the legal marketplace has not helped with efforts to eradicate the black market and transition consumers to the regulated suppliers. Price and quality are the perceived common denominators for sticking with the black market.

Meanwhile, it’s crunch time for licensed producers across the country as they try to catch up with increasing demand by building bigger facilities and expanding production capacities. And they have to do it in a way that does not compromise the quality of their cannabis products.


“More focus and concentration need to be put on the quality of your product and producing it properly,” says master grower and cannabis grow consultant David Kjolberg. “The more time and effort they put into that part of the process, the easier the other end will be for them. For marketing, it’s easy to sell great stuff – it’s not so easy to sell garbage.”

Beyond the grow room
Proper cultivation of great cannabis plants is only half the battle when it comes to achieving high-quality cannabis products that Canadian cannabis connoisseurs have come to expect. The other half of the battle is won in post-harvest processing: drying, curing and packaging.

Oftentimes, the drying and curing can make all the difference for the end-consumer.

“You can take average genetics (cannabis plant), and with proper drying and curing, you can make a very enjoyable smoke. It’s not going to get any better, but it will be more enjoyable,” says Kjolberg.

Compromising quality for more products to market is not the way to go. There may be a perception that mass-produced products may compromise the quality. When it comes to cannabis production: is more less better? Not necessarily, Kjolberg says.

“It doesn’t matter how much cannabis you produce, if you are set up properly to dry and cure, and you have people who are actually experienced and skilled in drying and curing cannabis, you can still dry and cure as much as you can produce.”

An ideal cannabis production facility, no matter the size, will have dedicated spaces for growing, trimming, drying and curing, says the master grower from Wasaga Beach, Ont.

“When you start building out new facilities, you’ve got to plan for that.” Kjolberg says, “You’re going to have to dedicated it to the whole process – drying, curing, trimming, harvesting – all these rooms have to be at the forefront part of design and build.”

As new LPs come on board and existing LPs ramp up their facility expansion plans, designing and constructing the facility in a manner that will ensure quality cannabis are produced is key.

“It’s harder to do something after the fact than do it while you’re just getting started,” Kjolberg points out.

As the eerie voice from Field of Dreams wisely said, “If you build, they will come,” building a facility that takes into account the space required to grow and process good quality products will likely increase a licensed producer’s chance of securing a place among the “people’s choice” in the cannabis industry.

Once the building is properly designed, it comes down to the actual work that’s required to achieve a product that cannabis consumers will love.

“The drying, curing and packaging are crucial stages for maintaining the quality of the product,” says Deron Caplan, director of plant science at The Flowr Corporation, a licensed producer based in Markham, Ont.

“You can produce a very high-quality product but if you dry it poorly or don’t cure it long enough, it will be almost unsmokeable or will be of low quality,” he adds.

So, what is the proper way of drying and curing? There are as many ways to dry and cure cannabis as there are to grow them, according to experts we spoke with, but there are methods that cannot be compromised and can directly influence the quality of the end-product.

Cutting the plants to the stem level and leaving them to dry hanging upside down for several days is the typical practice among producers.

“Generally, you are not disturbing them when they are wet so you don’t lose as much of the oil that contains the cannabinoids and the terpenes that are the flavour compound and the smell compound,” explains Caplan, who is the first in North America to earn a PhD on cannabis production from the University of Guelph.

The process of drying whole cannabis plants prior to trimming reduces the moisture content in the flowers and helps prevent the proliferation of bacteria, yeast and mould, explains Flowr’s plant scientist. Once the threshold for moisture content is reached – the state where the flowers become more safe to handle and the risk of introducing harmful micro-organisms is low – then the plants are ready to be trimmed.

There are a host of trimming machines available in the market – dry trimmers and wet trimmers – but experts we spoke to maintain there is no substitute for hand trimming.

“Hand trimming is more detailed and basically, your trichomes are left intact,” says master grower Kjolberg, adding wet trimming is his preferred method.

Using dry trimming machines may result in the loss of trichomes on the cannabis flower, which may make the product powdery, Kjolberg notes.

Hand trimming is also a preference at Flowr, says Caplan, as this results in a higher quality product.

“The purpose of trimming is to remove as much leaf material as you can from the flower,” he explains. The leaves don’t contain as much resin as the other parts of the flower, so the more leaves can be removed the better the potency is.

Using trimming machines may produce a more uniformly trimmed flower, but can also result in the flower being inadequately or overly trimmed.

“From what I’ve seen, the technology is not there yet,” Caplan says. “It will probably get there eventually but it’s a fairly new industry – at least, legally. For now, I think hand trimming is the way to go.”

Properly drying and curing the flowers after trimming is crucial – making the final products not too dry and not too moist.

Environmental controls
The secret to achieving ideal drying and curing process: the environment.

“Just like in your grow facility, your environment is everything,” says Kjolberg. “You can have any kind of lighting, but environment is everything. It’s huge in your pest management program, keeping the plants healthy and not stressing the plant out.”

The same applies to drying and curing, he adds. Humidity and temperature controls can make or break the quality of your product.

Ideal range for temperature, according to our experts, is around 18 to 21 degrees Celsius, while relative humidity should be maintained at around 50 to 55 per cent.

“The humidity is going to be high when the plants go in wet. You’d want to get rid of that moisture on a consistent basis, but you’re not going to do it right off the bat… You’ll want to slowly be able to bring that humidity down so the plant will dry, but it will dry and cure,” Kjolberg explains.

A segregated drying and curing facility where the humidity levels and temperature can be controlled and adjusted according to ideal conditions is essential, he adds.

Curing the flower after trimming further removes unwanted moisture from the product, but not totally eradicate it, says Caplan. “We found there is consumer preference for certain moisture content. So, if you dry it too much it would be hard to smoke; it will burn too fast or unevenly.”

Kjolberg says moisture retention of around 16 per cent is ideal.

Sweat it
The length of time to dry and cure cannabis depends on when the desired level of moisture is achieved. There are no shortcuts to good quality products.

Slowing the process down, controlling the environment, regularly rotating the flowers so they don’t clump together and doing a series of sweating and airing – these are some necessary steps to quality.

“Cannabis kind of dries from the outside in, and in the inside out,” says Kjolberg, and taking the flowers through a “sweating” process is key.

He explains: “You want to put it in a container – a plastic bag works. You’ll want to share the moisture between the bigger flowers and the smaller flowers. Then you’ll want to take it out, break it down, and put it back on your rack.” Repeat process for about four or five times until you get the desired state.

“I’ve dried so much cannabis in my day that it has become second nature,” says Kjolberg, who was previously a master grower at Peace Naturals, one of the first licenced cannabis producers in Canada.

At this point, where the very young Canadian cannabis industry is just in its early stages, having widespread supply shortages is not ideal, but providing haphazardly-produced cannabis products in the market just to fill up the demand is less than acceptable.

To properly dry cannabis the way it was meant to be, it could take between three weeks to a month, according to Kjolberg. He cautioned against fast-tracking to process for the sake of profit.

“If there’s demand for the product and you need that product and you need to pay your bill, you have to dry as fast as possible. And you’re going to do that by putting dehumidifiers in the room and you’re going to be putting fans in the room, you’re going to put up the heat a little bit… Unfortunately, that happens a lot more often than I’d like to see.”

Flowr says it’s not willing to sacrifice quality over profitability.

“Even though there is this supply shortage, it’s important to ensure that we are still producing high-quality products,” Caplan says. “We are known for our craft-quality cannabis… if you cure for less time, you can turn around a lot faster but then your quality is lower.

“It’s important that we don’t let the demand overly influence the quality of cannabis in Canada because then the industry won’t get very far when we are competing with other cannabis industries globally.”


Mari-Len De Guzman is the editor of Grow Opportunity. Email her at

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