The unique odor and flavor profile of a cannabis plant can be attributed to specific chemical compounds called terpenes. Like THC and other sought-after cannabinoids, the majority of the terpenes are found in a cannabis plant’s trichomes (the mushroom-like structures that cover the leaves and flowers of a female cannabis plant). In nature, all species of plants create terpenes. Plants create terpenes to attract pollinators, to repel hungry animals or pest insects, and/or to attract beneficial insects or predatory animals for protection. In most plants, including cannabis, the concentration of terpenes increases as the plant matures. In other words, when the plant gets closer to its reproductive stage, more energy is used to attract pollinators or to protect it. As a cannabis plant reaches the end of its flowering stage, the terpenes are at their maximum content. When it is considered that the terpenes basically give each cannabis plant its unique flavor and odor, it should come as no surprise that horticulturists are employing products and techniques that specifically target increasing terpene production.
In most cases, it is not a single terpene, but a combination of multiple terpenes that contribute to a cannabis flower’s unique odors and flavors. Each terpene lends different characteristics to the cannabis plant’s overall flavors and odors. The following are just a few of the sought-after terpenes produced by cannabis plants.
Pinene is a terpene many are familiar with because it is associated with the fragrance of pine trees. The pine tree, or “piney”, smell found in some cannabis varieties is attributed to pinene. It is also believed that the terpene pinene is responsible for the “skunk” smell found in certain cannabis plants.
Limonene is another fairly recognizable terpene. This citrusy terpene is also found in the rind of citrus fruits. A strong citrus smell in cannabis flowers is most likely created by the presence of limonene.
Terpineol is a terpene with a lilac, citrus, or apple blossom odor. Terpineol is found in low concentrations in the essential oils of many plants, including cannabis.
Pulegone is a terpene with a minty odor and flavor. It is usually found in very small quantities in cannabis plants.
B-Caryophyllene is the terpene normally associated with a peppery odor. A cannabis strain with a spicy or woody-spice odor is most likely exhibiting its B-Caryophyllene content.
Myrcene is the most prominent terpene found in most marijuana varieties. Odors associated with myrcene are citrus, nutty, earthy, and clove. The specific odors will vary due to slight changes in the overall makeup of the essential oils.
The majority of nutrient additives that are designed to enhance the flavors or odors of cannabis plants are actually targeting and increasing terpene production. Some of the most popular cannabis flavor enhancing products are carbohydrate-based. Put another way, they provide sugars to the root zone, thus enhancing the beneficial microbial population. They also simply give the plant access to more carbohydrates. A large number of flavor enhancing additives also contain amino acids which contribute to the overall health of the plant. Providing the plant with sugars and/or increasing the plant’s overall health indirectly helps increase terpene production. There are also nutrient additives that are specifically designed to increase terpene production and are advertised as such. These additives utilize naturally occurring plant compounds that are bio-osmotic potentiators. These compounds encourage plants to up their production of terpenes and essential oils. In other words, they make cannabis plants increase their production of trichomes.
The last few weeks of the flowering stage is a critical time for terpene production in cannabis plants. As stated earlier, a plant creates terpenes to protect itself and to increase its chances of successful reproduction. This explains why a cannabis plant expends the most energy on producing terpenes during its final stages of flowering. And this is just one of the reasons why a cannabis grower should reduce or alter his or her feeding regimen during the last stages of flowering. The vast majority of a cannabis plant’s terpenes are found in the trichomes on the flowers or buds. Particular elements, such as nitrogen, are known to slow down flower formation. This reduces the production of trichomes and, in turn, the production of terpenes. A balanced nutrient regimen with a reduced amount of nitrogen should be used throughout the flowering stage. It is important to completely eliminate nitrogen from the feeding regimen during the final two weeks of flowering. This will help promote larger flowers and more trichomes/terpenes.
The atmospheric conditions of an indoor garden or greenhouse can also significantly impact the terpene production in cannabis plants. For example, the high temperatures from an artificial light source can actually damage terpenes and essential oils. This is one reason why it is recommended to lower the operating temperature of a flowering room during the last couple weeks of flowering. Generally speaking, the optimal operating temperature for growing cannabis is 75-80 degrees F. During the last couple of weeks of flowering, some growers will drop the temperature range by 5-10 degrees F. This reduction in temperature will slightly stress the plant (which actually increases terpene production) and protect the terpenes from being damaged by excessive heat. A gardener must be careful to not drop the temperature too low, as operating temperatures below 60 degrees F can be counterproductive and reduce yields. It is also important that there is not a differential of more than 10 degrees F between the “light” and “dark” periods. A large temperature differential between the “light” and “dark” periods can potentially cause humidity-related issues.
Ideally, the humidity level in a cannabis flowering room should fall between 50-60%. However, during the last few weeks of flowering, the humidity level can be dropped to around 30% to slightly stress the plants. This will most likely require a dehumidifier. The lower humidity will lightly stress the plants, which, in turn, will increase terpene production. As with reducing the operating temperature, the lower humidity during the last weeks of flowering will increase terpenes and also protect them by reducing the likelihood of molds and mildews.
In addition to providing plants with a flavor enhancer or specific terpene enhancer, the most effective way to increase terpene production is to lightly stress the plants during the flowering stage. Light stress causes cannabis plants to increase the trichome and terpene production even more. When done correctly, the physical manipulation of cannabis plants can increase terpene production during the crucial final stages of flowering. Always use caution when deliberately initiating stress. Although the benefits can be great, it should always be done cautiously so as not to over-stress the plants. The goal is to stress the plants just enough to boost terpene production, but not enough to cause any serious harm. Two simple plant manipulation techniques that will lightly stress the plants and, therefore, promote more terpene production are super cropping and undercutting. Both techniques can be used to not only increase terpene production (due to the light stress), but also help the horticulturist more efficiently use his or her given light energy.
How and when the cannabis plants are harvested will directly affect the concentration of terpenes. In fact, properly timing the harvest is one of the most important factors over the concentration of terpenes in the final product. Cannabis plants that are harvested too early will not yet have reached their maximum terpene production. Cannabis plants that are harvested too late will also have a lower concentration of terpenes due to the degradation of terpenes over time. Drying and curing will also affect the terpene concentration. After being cut down, cannabis plants should be hung up to dry. Drying a cannabis plant too quickly can negatively alter the terpene profile. To get the dried cannabis flowers to retain the odors that are similar to what they were while growing, the cannabis must be dried slowly (especially for the first few days). When done correctly, cannabis flowers should take anywhere from 7-14 days to dry. They should then be placed in long-term storage containers where they will continue to cure.
The nutrient additives used, the atmospheric conditions of the growing environment, and the manipulating and harvesting techniques a grower uses will all directly influence the terpene profile of the cannabis plants. The fact that terpene production can be altered by atmospheric conditions and particular products and/or techniques further illustrates how every garden will produce a slightly different result. Even when two cannabis horticulturists grow the exact same strain, there are usually slight differences between the finished products. These subtle differences can be attributed to each crop’s unique terpene profile. As more knowledge is gained regarding the medicinal properties of terpenes and techniques for increased production are fine-tuned, the medicinal and recreational potential of cannabis will only continue to expand.
Eric Hopper is Editor in Chief for NUGL Media Group. He can be contacted at email@example.com.