When Does Cannabis Start Producing THC?

When Does Cannabis Start Producing THC?

Cannabis growers go bonkers over THC production hitches. It seems THC is the only thing that matters to those who grow for recreational use. And THC being the only mind-bending cannabinoid, it makes sense why it’s such a sought-after cannabis component.


Knowing when the THC begins to form can help you if you want to use the leaves after pruning. It wouldn’t make much sense to cut the leaves to make hash when they hold nothing mind-altering in them.


But there are other reasons why a grower might want to know when cannabis plants start producing THC. Some growers just want to know when to give the plants their most attention. 


When the THC begins to form is a contentious issue. And what makes it the more complicated is that THC isn’t only present in the flowers— trichomes— the cannabinoid-containing bulbous crystals can be present on the leaves and stalks of the cannabis plant.


As if that isn’t enough, trichomes can be spotted on cannabis before flowering. If you’ve ever spotted those glittery, hair-like spikes on the plant’s leaves, those are trichomes.


It thus isn’t clear whether cannabis plants begin producing THC— albeit in low quantities—much earlier than we credit them for. But guess what, it doesn’t matter. 


The THC available earlier on the stalks and leaves aren’t potent because they haven’t matured. And thus, you should be more concerned with when the THC begins to form in the flowers so that you can take care of them better.


When Does Cannabis Start Producing THC?

Cannabis starts producing THC in the second week of flowering. By the third week, the THC-containing trichomes become more pronounced, appearing as colorless crystals. The THC will be available alongside other cannabinoids, but these chemicals won’t be concentrated until the last stages of flowering, when they’re mature.


You shouldn’t worry much about when the cannabinoids begin to form. Just pay close attention to the trichomes because they hold the most THC. 


You might spot the glistening crystals on other parts of the plant like the leaves and stalk, but most THC is formed and nurtured by the flowers.


The moment the trichomes begin to form, treat them like the means to an ultimate end— potent buds. Protect them from physical contact because they can be knocked off easily and keep the environmental factors in check.

RELATED READ: What Week Do Buds Grow the Most?

When Does Cannabis Start Producing THC?
Trichomes are the THC-bearing crystals. You spot them, you’ve got THC.


How Is THC Formed?

The formation of THC follows a long path. The process begins with the plant producing geranyl pyrophosphate. The chemical is instrumental in creating THC because it binds with the olivetolic acid to form CBGA.CBGA is then turned to THCA with the help of enzyme synthases.  THCA is then decarboxylated to form THC. 


Curing can initiate the decarboxylation process, but the buds must be exposed to heat to decarb fully.


This explains why you can’t get high by eating raw weed. You have to light it up or vape it to activate the cannabinoids. It also explains why you have to decarboxylate cannabis before making edibles. 


The compounds might be at their peak but are inactive until exposed to the heat that turns THCA to THC. 


When Do Trichomes Appear?

Trichomes will appear in the third-fourth week of flowering. They begin as crystal filaments on the surface of the flowers. However, Sativa-dominant strains take a little longer to show their trichomes.


In the beginning, the trichomes will be colorless and are less potent. They’re just beginning and lack the psychoactive components that growers look for. 


As the trichomes mature, their color will change to milky white, signaling the improving concentrations of critical cannabinoids. 


The milky-white trichomes signal the peak of THC concentrations. If you wait till trichomes are amber, the THC shall have begun to degrade. 

RELATED READ: How Do I Make My Trichomes Bigger?


In conclusion, cannabis plants begin to produce THC within the first two weeks of flowering. However, the cannabinoid-rich trichomes will become visible by week 3-4 into flowering. For most people, it’s the trichomes that show the progress of the cannabinoid concentration. Keep an eye on the trichomes, notice all the color changes, and harvest when the THC is at its peak.


  1. https://www.autoflowering-cannabis.com/when-do-trichomes-appear/
  2. https://www.royalqueenseeds.com/content/204-how-thc-and-cbd-are-made-understanding-the-cannabinoid-pathway
  3. https://www.leafly.com/news/science-tech/peak-thc-cbd-levels-for-cannabis-strains