Friday, I'm in Tubs: The How and Why of Drying and Curing Cannabis

Why Do We Dry And Cure Cannabis?

Well, this is an easy question to answer, especially if you think about how difficult it would be to try to light a wet joint. The obvious answer is that the bud needs to be dried out so it’s easier to light, and this is 100% correct. However, there is a lot more going on during the dry and cure process than just getting the flower dry enough to light up. I’ve always said that you could be the best grower on the planet, but if you don’t dry and cure your cannabis properly, all that cultivation expertise is for naught. So, there’s more to drying and curing than just getting the flower dry enough to ignite. And knowing why we dry and cure cannabis will help us answer the question of: how do we dry and cure cannabis?


Understanding Plants

First off, I want to share a bit of a macabre story that we all need to understand about many of the plants that we harvest for eating or ornamental purposes (i.e. cut flowers). Let’s say you have an apple tree in your backyard. Every season it produces some of the best tasting apples you’ve ever tasted. You pluck an apple off the tree and immediately take a bite. In a different context, this would be a horrifying story, since that apple is still alive. That is correct…you have been eating these poor helpless apples while they’re still living. Same thing goes for an apple that was harvested long ago and is sitting in a fruit stand. That apple is still alive.

How does our bloodlust for consuming still living fruit pertain to drying and curing cannabis? Excellent question, and I promise you I have a point. When cannabis is harvested, it too is still living. The floral tissue is still biosynthesizing secondary metabolites. Examples of secondary metabolites in cannabis are compounds such as THCA or CBDA. That tissue typically will cease to be living when it dries out to a point when the cell membranes rip away from the cell walls and therefore break apart. While the harvested cannabis is still fresh and wet, those cells are still alive and chugging away. The enzyme responsible for creating THCA (the enzyme is called THCA synthase) does not magically disappear once that flower is cut from the branch. It also doesn’t immediately denature into an inactive form. That means that as long as there’s still a supply of CBGA in the cells, THCA synthase will continue to catalyze the reaction that converts CBGA to THCA. This means that the overall THC content of a harvested flower continues to increase even after harvest; however, if you dry too quickly or at temperatures/relative humidities that are suboptimal, you can halt the continued post-harvest THC accumulation in the flower.

  1. So, this makes sense. We want to dry the bud out as slow as possible, right? Well, not so much either. We have to tread the fine line of drying the flower slow enough to allow for a continued increase in THC content, but fast enough to decrease the chance of fungal spore germination and potentially a full-blown fungal infection. Properly dried/cured cannabis flower can last for a couple of years without much degradation in quality as long as its stored properly. Without properly drying and curing, the bud will almost certainly rot from fungal infection.


Other Processes At Work

Now that you know that enzymes are still working at what they do best even after the flower is harvested, you might be asking: what other processes are still at work in a recently harvested cannabis flower? There are many internal processes still at play here, including the breakdown of chlorophyll, which is of interest for cannabis consumers. Chlorophyll breaks down into metabolites, which along with the presence of other sugars already present in the plant tissue are seen as what can give that harsh smoke generally associated with improperly cured cannabis. Curing properly gives aerobic bacteria time to digest the chlorophyll metabolites and other sugars. We see the same processes occurring in tobacco curing. The how of curing tobacco is different than it is with cannabis; however, the why of curing tobacco is the same as curing cannabis. If you ask your average tobacco cure master about the benefits of curing, they will undoubtedly mention “smoothness” of the smoke being a significant factor.


How Do We Dry And Cure Cannabis?

Now that we know the basics of why we dry and cure, let’s discuss the how. There’s definitely more than one way to skin this cat, but I would like to focus on your standard methodologies of drying and curing cannabis. When you harvested your crop, you either completely bucked the flowers from the stems or you left the flowers attached to the stems. If the flowers are completely bucked, they should be laid out on a flat surface in a single layer. If the flowers are still attached to the stems (excess leaves may or may not be removed depending on what you’re going for), they should be hung on wires with plenty of space around them for better air movement. Speaking of air movement, we want to ensure there’s constant air movement in the dry/cure space.

If you read last month’s blog post (I will assume that everyone reading this now has already read last month’s post for my ego’s sake), you will remember that once the flowers are harvested we are switching from terpene production mode to terpene retention mode. This is mostly taken care of in dry/cure. The terpenes are volatile organic compounds (VOCs), which means they can volatize off if the temperature gets too warm. Terpenes will volatize at different temperatures, but some can volatize/degrade at temperatures as cool as 70°F. This is why I prefer to dry in a space that is maintained at 60°F. The more terpenes that are retained in the flower, the more flavorful and better aroma you will have when it comes time to smoke.

Humidity & Drying

The relative humidity (RH) of the dry space needs to be maintained as well. If there are significant fluctuations in RH, you are inviting fungal spore germination to occur (which is frowned upon). Maintaining the RH at around 50% is preferable. If it’s too dry, the flowers will desiccate too quickly (this won’t optimize the post-harvest THC accumulation). If it’s too dry, the flowers won’t desiccate fast enough (higher likely hood of fungal infection). The drying process can take up to 2 weeks, but is typically done in just around 1 week. You want to see your flowers to be just a bit crunchy, and the stems should snap and not bend. Don’t worry if your flowers don’t have the same pungent aroma it did when you harvested. That’s perfectly OK and to be expected. That strong cannabis aroma will return after a proper cure.


Curing – Time For The Tub

Now that you’ve dried your flowers, it’s time to “tub” them up. I say “tub” because a lot of larger scale productions use tubs to cure their product, and that way the title of this blog post is a play on words for The Cure’s Friday I’m in Love. All that is really necessary is for the flower to be sequestered in a fairly airtight vessel (Mason jars work very well here as well). We’re purposely removing that air movement around the cannabis here. This is where the aerobic bacteria get a chance to metabolize those sugars inherent in the flowers. Notice that I used the word “aerobic” here. We do not want anaerobic bacteria going to work here, as that will result in an ammonia smell and rotten flowers. If you do smell ammonia, that typically means that the flowers haven’t fully dried. You should give the aerobic microbes a bit of a boost here by giving them more oxygen. This is why you “burp” your flowers. Opening up your sealed container (be it a tub or Mason jar or glass Tupperware) will reintroduce oxygen into the environment to assist the metabolism of those sugars. Additionally, you can gently move the flower around inside the tub. For the first week of cure, the flowers should be burped once to twice per day. After then, your curing flower will only require a good burping every other day or so.

The question of how long should your flower be in cure is somewhat subjective. Typically, flower that has been properly cured for 2-3 weeks is ready to be smoked; however, most cultivars are best when cured for up to a month or two. I happen to know someone who buries his flower in Mason jars in his backyard after the initial cure period. He does his “deep cure” for over a year before he will smoke it. There is absolutely nothing wrong with this other than having to be patient to smoke your flower. As long as it was properly dried and burped in the initial week of cure, that cannabis can be stored for a very long time in a dark cool place.

What happens if you dried too much? If you didn’t dry enough, it’s easy to remedy (just dry more), but what happens if you were a bit too zealous with your drying? This can be an issue as the flowers will be brittle and will be more likely to lose its trichomes (and thus potency). There are products on the market that can be used to help rehydrate your overly dried flower; however, you can also use something as simple as corn tortillas that you can buy from the grocery store. Place the tortillas in the cure vessel overnight. The next day turn over the flower. You will find that the flowers will have rehydrated. Rinse and repeat to your liking.

Now that you know the basics of drying and curing your cannabis, I am sure you are very excited for next month’s blog post about trimming. It’s perfect timing for the new Mary Poppins movie coming out since I have titled it: “Trim Trim-A-Tree, Trim Trim-A-Tree, Trim Trim Some Boo”.



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