Terpenes are responsible for individual plants' signature taste and smell.
For example, while cannabis plants produce hundreds of terpenes, some are more commonly expressed than others, said Shaye Donald, a horticulturist in the professional technical services team at Hawthorne Gardening Company.
"We've got a lot of data from one of our partners up here in Canada, A&L Labs Canada. They conduct testing to show how much terpene content your flowers have," Donald said. "Some of the data that they have shows that the most common terpenes found in [plants] are myrcene, caryophyllene, limonene, humulene, linalool and pinene. There's a whole bunch of other ones, but those are the ones we are primarily concerned with."
Donald said it's vital for growers, producers and breeders to know what the most common terpenes found in their cultivars are because the combination of the different molecules plays a crucial role in the final products' effects, scent and flavor.
"It is the combination of these different terpenes that contribute to giving the consumer that subjective experience of, ‘This strain smells like citrus,’ or, ‘This one smells fruity or skunky.’ These scents are largely driven by the terpene content," he said.
Aside from terpenes' role in the plant's flavor and smell, they also contribute to its growth and environment. For example, plants naturally produce terpenes to help protect themselves, as they work to prevent disease, restore damaged plants, attract pollinators, repel pests and more, Donald said.
Influence Terpene Production
He said that some of the significant factors that influence a plant's terpene production are cultivar selection, fertilizer and growing environment.
"Number one is going to be genetics. That's always going to be your maximum achievable, and that's going to drive that mix of different terpenes," Donald said. "And then next is going to be hitting all your setpoints, [such as] making sure your plant is nice and healthy. Then, I always advocate for light stress, whatever that's going to be."
During the flowering stage, when terpenes are at their maximum content, growers can use techniques to lightly stress the plant to influence terpene production. Some of these techniques include drought stress or changing fertilizer recipes, Donald said.
He provided an analogy: "I always describe it as [going to] the gym. It's like you could have all your nutrients, you could be eating right and going to the gym, and you will give the most benefit to your body because you are giving light stress to it. This won’t work as well if you aren’t eating correctly. Similar to the plant, you want to make sure that it's getting everything it needs first, and then stress it out a little bit."
Donald said stressing the plant without ensuring it has proper nutrition first can cause damage.
"I think the danger is if you don't have the proper fertilization first, and then you apply a little bit of stress to the plant, if [the plant] is not able to produce those terpenes because of missing nutrients, then you're going to get in trouble,” he said. “So, you have to make sure the plant is well fed first and then kind of start playing with it to encourage that terpene production. But, if a plant isn’t in great condition, and now you're just stressing it, [you are] potentially risking its health and putting your crop in danger.”
Growers can also use nutrients to help boost terpenes in plants.
For instance, Hawthorne's Terpinator product is a high-potassium fertilizer designed to help increase terpene concentration.
Terpinator is primarily going to be effective toward the end of the flowering stage, Donald said.
"That tends to be when most plants [start to produce more] of those secondary metabolites, things like terpenes, cannabinoids and other metabolically expensive molecules,” he said. “So, we want to try and match that demand and maintain higher levels, especially potassium at that point."
Enhance Your Grow
Utilizing techniques to help increase the terpene concentration in your grow can result in your cultivars having a better flavor and scent, which can correlate to a higher quality end-product for consumers, he said.
And as the market continues to evolve and mature, Donald said he thinks the industry is "going to see more of a focus on terpenes, specifically for benchmarking what makes a ‘good’ or ‘unique’ crop." Additionally, he said he thinks "potency is a high driver of demand for now, but long term this may become less of a focus for the industry.”
He provided another suitable analogy: "I don't think it has been since I was 19 or 20, I’m in British Columbia so that’s when we can start to drink, where I went to a liquor store and looked for the cheapest bottle of wine or a drink with the highest percentage alcohol content. After wising up to enjoying the experience, now I'm willing to pay a little bit more for something that tastes nice or has a novel smell. Being from the west coast, I’m your typical hoppy IPA beer fan, which I think has a lot of parallels. I'm not really looking at the alcohol content. I'm concerned with what smells the best, what tastes the best, or what's going to give [me] the best experience, [and] I think that cannabis is going to continue to evolve towards that long-term."