On judging cannabis, then and now

Gwilt tests 30 to 60 strains weekly, sending three to four g per variety for third-party THC tests and accepts 15 percent to 20 percent of those

Evaluating excellence in cannabis flowers was once the province of either unlicensed growers or dispensary owners. In the new legal market, this task is being shifted largely to licensed producers (LPs), a shift that, interestingly, has brought few changes to the field.

Dana Larsen, who has owned The Medical Dispensary in Vancouver since 2008, employs premier cannabis testers. One is Carol Gwilt, co-owner of Weed, Glass & Gifts dispensary, who has been testing cannabis for 15 years. Gwilt begins this task “by interviewing growers on their methods.”

Checks a staged process

“All cannabis on offer,” Larsen notes, “is then assessed in three stages.” A first, “pass/fail test, examines buds under a microscope at 60 to 100 times enlargement.” Ideally, one sees densely packed bracts [modified leaves] studded with trichomes, the tiny, mushroom-shaped, translucent structures that contain the plant’s cannabinoids.


The second and third stages involve smoking samples. Stage two “tests for cheminess”—a chemical taste that might remind a person of a floor-cleaning agent or shoe polish—which indicates the presence of fertilizers and other additives. Good growing practices require all nutrients to be “flushed out of the plant [by watering intensively] before harvest.”

At this point, states Larsen, “buds are lab-tested for pesticides, and CBD/THC profiles. The final stage assesses fragrance, which should be pleasant [fruity, spicy or lightly floral depending on the variety]; and checks the strength and style of the effect.”

Larsen and Gwilt routinely reject 80 percent—in general, that percentage has remained stable for years—of the cannabis they test.

Gwilt reports that she tests 30 to 60 strains weekly, sending three to four g per variety for third-party THC tests and accepts 15 percent to 20 percent of those. There are slightly fewer growers coming to her since adult-use cannabis legalization on Oct. 17, 2018, she points out, but adds there is no dearth of product from which to choose.


Enter the government

With legalization of cannabis for adult use, Health Canada has come to play a role, though an intentionally limited one. Health Canada “requires that all be tested for microbial and chemical contamination, but it has not established grading standards for dried cannabis, reports Tammy Jarbeau, senior media relations advisor for the federal department.


Derek Pedro, master grower and design, cultivation and production partner at WeedMD, appears to have welcomed the challenge. A former licensed medical grower with 14 facilities, Pedro has bred “54 cannabis varieties,” and says he knows them “as well as I know my own kids.”

On quality, he shares much with Larsen. Pedro is careful to flush all plants prior to harvest, and expects all buds to “diamond out”, that is sparkle with trichomes, when viewed under magnification. “Taste and smell,” he adds, “should be enticing” [smell should never be acrid, or reminiscent of cleaning agents]. All buds are then sent out for third-party lab testing, as per the federal requirements.

To fine-tune his assessment, Pedro uses a focus group, which currently consists of 12 clients. He grows small, select batches of plants, offering “samples of these at reduced cost, to medical clients.” They provide feedback, and that determines what he grows in quantity.

Lisa Campbell, CEO of Lifford Cannabis Solutions, which markets LP cannabis, agrees with these criteria, emphasizing the need for testers to try products first-hand. Ash colour in smoked cannabis is a good indicator of quality, Campbell notes. “Ash should never be dark. White or very pale gray ash indicates thorough flushing,” she explains.

One key difference between Larsen and Pedro, however, is their respective views on curing cannabis. Curing entails hanging cannabis branches upside down in a dark room at 10 C to 20 C for a set time, in a controlled environment.

Pedro cures his buds for a week; Larsen and Gwilt favour three to four weeks. “The extra time,” explains Gwilt, “breaks down the starches and sugars that moulds and yeasts feed on, and mellows the resin, producing a milder, smoother smoke.”

Books on cultivating cannabis by renowned experts, Jorge Cervantes and Daniel Boughen, who is from B.C., side with Gwilt.

Medical and recreational: different or the same?

Pedro’s choice of testers raises a question. Is there a difference between medical and recreational cannabis? Maybe not.


Gwilt sees “all use as medicinal”; while Larsen rejects the term, “recreational,” maintaining that it trivializes the plant. Pedro calls cannabis “preventive medicine,” and Campbell says she believes the key always is good quality.

While sources share more views than not on quality assessment, their hopes for the future inspire more lively debate. Larsen wants to see a wider range of substances legalized, Gwilt would like to see greater stability in the cannabis menus on offer, Pedro’s wish is for more randomized controlled trials, and Campbell would like a special category established for organic growers.