The most obvious reason to dry cannabis flowers is to remove enough moisture so they can catch fire for smoking. Wet flowers don’t combust, which is why picking flowers from a live plant and rolling them into a joint won’t work! But there are other factors at play beyond just the moisture content of cannabis flowers, and how readily they’ll combust. Other noteworthy changes occur within cannabis flowers while drying, although they’re not completely automatic. The right environment must be created and maintained for drying to be most effective. 

How do you know when to harvest and hang dry for peak ripeness? The answer can be found in the trichomes, and we wrote an article to help you time your harvest for optimum ripeness.  Read more in How To Harvest Cannabis for Peak Ripeness.

When the trichomes are displaying ideal maturity, the plants are carefully taken down branch by branch and hung upside down to dry. Delicate handling minimizes the amount of trichomes that inadvertently drop from the flowers. 

What Happens to Cannabis Flowers While Drying?

The most evident change that occurs during drying is the reduction of weight of the flowers, accompanied by a reduction in volume. Like humans, plants are composed mostly of water, meaning most of the weight of fresh flowers will disappear as moisture evaporates. Cannabis flowers lose around 80% of their weight during drying. 

But there are also unseen chemical changes that are taking place. For example, chlorophyll, which is the green pigment in cannabis that’s essential to photosynthesis allowing the plant to convert sunlight into energy, breaks down into metabolites. This is significant in part because chlorophyll imparts a harsh, unpleasant taste in smoke, much more so than the metabolites. Drying not only readies the flower for combustion, but it gives the chlorophyll contained within the opportunity to break down for a smoother and more mellow smoke. 

Another chemical change takes place with the conversion of cannabinoids from the acidic into a non-acidic form. Cannabinoids in their acidic form (e.g. THCA) can offer therapeutic value, but not to the extent that their non-acidic counterparts can. While THC is known for its psychoactive and euphoric effects, THCA doesn’t provide those same benefits. While drying, the THCA in cannabis flowers (and more specifically within the trichome heads), naturally converts into THC. The same goes for CBDA and others. So even if you could smoke freshly picked, wet buds, they wouldn’t get you high. This is because the cannabinoids are still in their non-psychoactive, acid form. 

In addition to the transformation of acidic molecules into non-acidic molecules, some cannabinoids will transform into others while drying. The most noteworthy is the change of CBGA into THCA. CBGA isn’t a highly desirable cannabinoid, but THCA is. CBG is a precursor to THC, but the transformation doesn’t happen in full until the plant is dried. While the cannabis flowers are drying, CBGA changes into THCA. And from this acidic form, further drying allows it to convert into THC. 

Do You Always Have To Dry Cannabis?

Humidity
Drying either too fast or too slow will have negative effects on the quality of cannabis flowers. Both temperature and humidity are important factors for a consistent and even dry over the course of a week or two. Significant swings in humidity levels invite mildew and fungal spores to germinate, so keep humidity as consistent as possible. 50% relative humidity is the ideal for a drying room.

Air Flow
Air flow ensures even drying and keeps the risk for mildew growth at bay. Especially if humidity is any issue, air flow is essential to keep pockets of moist air from collecting in the drying room. Keep air flowing with fans, but not blowing directly on the flowers. This will lead to rapid drying, which is a negative.

Light
Light degrades cannabis, so make sure the drying room is dark. Darkness facilitates a positive environment for the right chemical reactions to take place in the flowers, without excessive degradation.

When Is Drying Complete?

Drying normally finishes between one and two weeks, but it’s not the length of time that’s most important to monitor. Rather, pay attention to the feel of the flowers and stems. The flowers should feel just a bit crunchy when gently squeezed between your fingers. Another sign that the flowers are ready to go into the curing phase, is that the smaller stems should snap when bent, rather than folding over. 

After hang drying on the branches the flowers are trimmed, removed from the main branches, and placed in sealed jars for a cure. To learn more about curing, check out our article How To Cure Cannabis Flowers. 

Conclusion

After months of care and attention in the garden, a correct drying process ensures your cannabis flowers reach their full potential. Incorrect drying environments can not only diminish quality but potentially ruin your entire crop. Setting up the environment to dry is just as important as setting up the environment to grow.  

FREQUENTLY ASKED QUESTIONS

Does cannabis always need to be dried?
No, if you're making bubble hash you can freeze the flowers instead of drying them. This is known as fresh frozen material. 

What is the best temperature for drying cannabis?
A good target temperature for drying cannabis is 65 degrees Fahrenheit. This temperature helps the buds dry before mildew or fungal infections can take hold, while remaining low enough to preserve volatile terpenes. 

What is the best humidity for drying cannabis?
50% relative humidity is the ideal for a drying room.

Can I have the lights on in the drying room?
Light degrades cannabis, so make sure the drying room is dark. Darkness facilitates a positive environment for the right chemical reactions to take place in the flowers, without excessive degradation.

How can I tell when cannabis is dry?
Drying normally finishes between one and two weeks, but it’s not the length of time that’s most important to monitor. The flowers should feel just a bit crunchy when gently squeezed between your fingers, and the smaller stems should snap when bent, rather than folding over.