Decarboxylating Marijuana – The Internal Process of THC Formation

Reading time: 5 minutes

Chlorophyll collects light hitting the leaves of cannabis plants. The light is stored as energy, part of which is stored to use later, and part is used to split H20 into O2 and H, oxygen and hydrogen, respectively.

This process is how plants ‘exhale’ oxygen. Plants also absorb CO2 through the reaction in photosynthesis called carboxylation. This CO2 combines with free hydrogen to create carboxylic acids.

Carboxylic acids are made up of hydrogen, carbon, and oxygen: the most relevant of these acids to growers and cultivators is delta-9-tetrahydrocannabinolic acid. Cannabidiol and Cannabinol, two other active ingredients in the plant are also made of carboxylic acids. There are a variety of other acids which have various purposes, but these three are the most relevant for most growers.

The effect of cannabinoids

The effect of cannabinoids

Delta-9-tetrahydrocannabinol (commonly called THC) has been found to have some beneficial health effects, but is not the active ingredient sought by smokers.

It doesn’t provide a “high”. While the plant is still living and growing, a large percentage of its THC remains in THCA form, which is one of the primary reasons that plants must be dried and cured to have strong drug effects. Extra CO2 molecules strongly inhibit the potency of the plant.

The THC itself is formed inside the plant through the process of decarboxylation. As suggested above, this is the removal of the extra C02 molecule.

This is one of the primary reasons why curing is such a vital part of the process of cannabis harvest. The dehydration and heat directly affect the conversion of THCA into THC, as well as determining the presence of other cannabinoids. Proper decarboxylation helps ensure the highest final yield of THC. Make sure to download my free marijuana grow bible at this link and grow like a pro!

Curing cannabis

Curing cannabis

Moisture is the most important aspect of the cannabis curing process. To begin curing, cannabis should be dried until most of the moisture has been evaporated. The best place for this is somewhere dry, dim, and cool. Good circulation is also essential.

The plant must be dried as quickly as possible. If it remains wet for an extended period of time, a grower risks the invasion of fungus and mold, which will irreparably damage the plant. Stay vigilant in the early steps of drying the plant; one of the most common mistakes is to allow a plant to rot by letting it stay moist for too long.

After the plant has dried entirely on the surface, it will still retain moisture on the inside. The next step is to place the plant matter in a sealed container and leave it. The moisture will disperse throughout the plant and rehydrate. Some growers refer to this stage of the process as sweating because moisture can condense on the interior of the container.

During the sweating stage, it’s imperative to open the jar intermittently and re-circulate the air inside the jar. This will help stave off the previously mentioned mold and fungus. Depending on the moisture of the plant matter, it may be necessary to remove the plant entirely and repeat the drying process before continuing with ‘sweating’. These two steps should be repeated as necessary until the plant matter has dried appropriately.

Download my free marijuana grow guide and start growing high THC strains.

Decarboxylating cannabis

Decarboxylating marijuana

The heating process automatically occurs when a plant is burned, vaporized, or smoked, but for tinctures or edibles, it’s still important to make sure decarboxylation has occurred. It’s best to do this in two separate steps, in order to ensure a high quality finished product.

First, the plant matter should be broken up as much as possible. This is a basic physics concept. Smaller particle size means that there is more exposed moisture for air circulation and heat to take advantage of in the dehydration process. The smaller the pieces, the greater the surface area, and the easier and more efficient it becomes for heating. The key here is to first ensure proper dehydration of the plant matter without burning or scorching it.

It should be warmed to about 200 degrees Fahrenheit for about 15 minutes or until totally dry. Although some sources will suggest a higher temperature, it’s valuable to keep the temperature below the boiling point.

As long as the plant still contains moisture, the water can boil and damage the cells, which will destroy the integrity and appearance of the plant. Additionally, a lower temperature lowers the risk of mistakes, because there is less worry about forgetting about it. Remember, the first step is to dehydrate the plant. Don’t burn it or let it get too hot!

After the cannabis plant matter has totally dried, there is less risk in letting the temperature rise above the boiling point. Once there is no water in the plant material, raise the ambient temperature up 25 to 40 degrees, to 225 or 240 degrees Fahrenheit. Let the plant sit at this temperature for about an hour. This process will help to accelerate the decarboxylation and conversion of THCA to THC. This step requires the most care: it’s important not to let the plant ‘cook’ for too long, and, above all, make sure that it isn’t being scorched or burned at all.

Once you’ve completed these steps, you will have decarboxylated and cured your cannabis and it is ready for whatever purpose you have planned.

Thanks for reading. Please leave comments or questions below and don’t forget to download my free grow bible.


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Robert Bergman

Robert Bergman is an Amsterdam-based marijuana grow expert who has years of experience from small grows to massive operations. His passion for growing led him to develop his own Gold Leaf strain. Now, Robert is dedicated to sharing his knowledge with the world.... [Read full bio]

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52 comments on “Decarboxylating Marijuana – The Internal Process of THC Formation”

  1. It’s done on a cookie sheet. Boiling point is used in referring to the water contained in the plant. I would have just said you don’t want to get it to hot, but there’s something to be said for accuracy. Sorry about every first letter being capped, IDK why it’s doing that.

  2. I appreciate your knowledge and your smooth Presentation.
    I feel that you will tell the Truth ¿ What CHEMICALS are The Labs OR the Companies adding to THE MEDICAL VARIETIES, or not.? Added Chemicals can be dangerous and the Medical Grades are So Powerful Today. What have you heard or seen ? This child of the 60’s needs to make an Informed Decision ! Thank You.
    Yours, John

  3. Is decarboxylating done in water or on a cookie sheet. You talk about drying and about not letting it get above boiling. Im confused

  4. so when you were describing the decarbing process you never said what to put it in, then you were talking about water boiling. What water? Are you placing the plant in water? Is it on the stove? I was always informed to use the toaster oven

  5. 1 page says to decarboxylate at 200 for 15m which i did for an entire batch of tincture. now i read another page that says after this step to bump up the temp and bake for up to another hour. now which is it?

  6. I have COPD and use a nebulator. How do I convert either herb or kiff (from the bottom of my grinder) to make a tincture that I may use in my nebulizer?

  7. Thank you for sharing your Experiences.
    Without this plant I would not be walking or sleeping.

  8. Just want to thank Robert for all the tutorials and information.
    Some day I hope to be able to grow your Purple Haze and also Northern Lights.
    Keep up the good work.

  9. I decarb in the oven then cook it in coconut and lecithin for capsules. My slow cooker gets up to 255-260 on the sides. Is that to hot? The center stays about 225.

  10. No method of decarboxylating mentioned; got this from Leafly HTH

    In order to decarboxylate cannabis at home, all you need is some starting material, an oven set to 220-235 degrees F (depending on your location and oven model), some parchment paper, and a baking tray. Finely grind your cannabis until the material can be spread thin over parchment and placed on your baking sheet. Allow the cannabis to bake for 30-45 minutes, or longer if desired.

    But I would think this would smell the neighborhood up. Here’s another way that might not be so stinky (also from Leafly)
    Cannabis can also be decarboxylated in a slow cooker by introducing solvents such as cooking oils or lecithin. These methods create infusions that can be used in a variety of cooking recipes, topicals, and even cannabis capsules. Since they contain decarboxylated cannabinoids, they will be effective any way you choose to consume them.

  11. Sorry, I forgot to mention, this is for max CBD, not worried about THC, in case that makes a difference! Thank you 🙂

  12. Hi, I’m going to be making tincture and tea at some point. Do I still need to decarboxylate for either? Won’t the alcohol have the same effect, or the boiling water with tea? How about if I store fresh straight to freezer, will freezing have the same effect, or do I still need to decarboxylate once defrosted? Thanks!

  13. No. Your weed should already be dry when decarboxylating. Never use a dehydrator for cannabis in any application. undried, uncured cannabis contains too much chlorophyll.

  14. Yamil,

    I am not sure what you are talking about precisely…

    I can tell you this. You do not want to dry Cannabis in the oven, period. Dry Cannabis correctly by hanging it in an airy cool dark room.

    Good Luck 🙂

  15. Hi Robert I’m very ignorant in this subject… by heating up you mean in the oven or pan with water? Again not knowledgeable at all! Thanks

  16. You can keep your plants short a few different ways. One way is the size of the pot. If your plant is in a 1 gallon pot, it will naturally be a much smaller plant than if it was put into a 5 gallon pot. It matters a great deal and can be useful to help keep your plants from being giant beasts. The trimming you do while the plant is vegging is also important. I like shorter, bushier plants myself, so I ‘FIM’ my tops when they are in veg. Never after they have started flowering. You can also use a physical barrier, such as a chicken wire box. It takes a little training, but the plant will stay in the confines of the box, for the most part. You mentioned that you bent your plant, that’s another way, you can do that throughout the plant cycle. The last thing I would say is that you can also just chop off the tall cola’s. Like the ones that stick over your fence. I’d rather not do that if they are juvenile and not mature, but it’s always an option. The plant will still grow fine without the cola’s, it will direct it’s energy to other parts of the plant. With a clean cut, I’ve found it doesn’t stress the plant either. Hopefully that gives you some ideas. My specialty has become short plants, so I hope it helps you!

  17. Barbara Waaka,

    You boil it in a sealed mason jar, filled to the top with your flower. Boil for one hour. Keep sealed until jar and contents are 100% cold. Good Lcuk JUst like canning except the process takes an hour.

  18. I’m confused Robert … the cannabis I have is fully dry and so I’m confused as to how to heat it to 225 f+ without it burning .. please advise and thanx for your info … you rock xo

  19. Hi Patrick, yes you do. Take a spoonful of your oil, hold it over a lit candle and add the hash. Good luck! – I❤️GM

  20. Do i need to decarboxalate hash from dry ice? When making e juice or oil? Thank you

  21. Lynn,

    It is always good to start with a plan for new grow environments. It sounds like you grew a plant in a tent until it got too high and you bent it over. That method works, and I usae it a lot

    The more common method is called SCROG. We are in a trichome development article (off topic), so; I suggest you read Robert’s article on SCROG and then join our support forum where we have many friendly members and staff using this method and always willing to share the knowledge to lead you to a successful grow.

  22. Hi, i was talking to a light supplier and he was telling LED is no good for growing because the light spectrum’s are wrong, is this true or false.

  23. How do you keep plants short. Trying a tent for the first time, can’t find information on it. Had to bend.

  24. Second question- If I grew Blueberry (fem.) , which can grow to 6 ft. , would be too tall for my space ( indoor ). Is it possible to trim them up to stay under 3 ft.,and yet produce their cabability .Crazy about the CBD and THC levels , not to mention the yield potential.

  25. Am I overeading this or could the , Curing , be skipped , if, product was Decarboxylated , only , instead ? What difference would it make ?

  26. This is a matter of personal choice. Every grower applies his or her own belief as to what they see in the microscope. When you see what you perceive as the perfect balance of clear, cloudy, amber trichomes; You flush.

    Don’t try to complicate this simple idea. New growers can read all they want to. New growers will not learn unless they view and experience results after making these decisions, on their own.

    Nothing will take the place of personal experience. All we can do is point inquisitive growers in the right direction. Peace.lw

  27. I’m not quite sure what you’re saying because when I get the perfect blend of: Clear, Cloudy, and Amber I harvest.
    If you’re flushing for 2 weeks AFTER you have your Perfect Blend won’t that’be going past that?
    If I have a strain with a 9-10 week flowering time I stop nutrients at about 8 weeks.

  28. dennis,
    When to stop applying nutrients is determined by the maturity of the “Trichomes. We monitor the Trichome production using a 60-100x pocket scope, jewelers loupe, etc. We want to see the perfect blend of: Clear, Cloudy, and Amber colors when viewing the Trichomes late in the bloom stage.

    Once you achieve the desired balance, and feel that the plant is ready; You stop nutrients, and flush the plant for 1-2 weeks. Happy Growing 🙂

  29. robert i was wondering when to stop fertilizing my osh kosh is 42 inches high and starting to bud very hairy thanks again robert get site

  30. […] to popular belief, marijuana is actually a remarkably safe drug. Despite the fact that THC and other cannabinoids are the primary, active ingredients, there’s no study that suggests that its lethal. Other […]

  31. No. Where did you get that info? You want to cure in a cool dark space with as low humidity as possible.

  32. the info you supply is great. do you suggest heating my medicine when curing for the max THC

    thanks jack

  33. Absolutely. Although, I would say the trichomes on the bud, is what you want to look at. I am sure the leaves will be fairly close in color, though.

    The only way to harvest exactly at the time, for the effect you want is to gauge the trichomes.

    Best way to get information and support during your grow, is to join our support forum. Happy Growing 🙂

  34. I am growing with LEDs and know from experience the bud hairs will turn amber, and even brown, long before the tricomes on the leaves become cloudy or amber. That, my dear, is my concern. Is the condition of the tricomes on the leaves the most accurate tell as to when a particular bud is ready for harvest?

  35. awesome site dude. havent smoked for over 10 years but im going to take it up again. thanks for remind what wonders a simple plant can do

  36. “As long as the plant still contains moisture, the water can boil and damage the cells, which will destroy the integrity and appearance of the plant.” You have already done that when the cannabis was ground up. You are extracting the THC not trying to preserve the looks of the plant. Not sure what the author intended to say but clearly that wasn’t it.