What Is Decarboxylation? How to Decarb Weed in the Oven, Microwave or Water Bath

Decarboxylation, or "decarbing," is the reaction that happens when you heat cannabis: it turns the inactive acid THCA into THC, the compound that actually gets you high. Smoking and vaping decarb your weed automatically, but for edibles, tinctures or salves you have to do it first, usually in an oven at about 105 °C (220 °F) for 45 to 50 minutes. That's why raw cannabis won't give you any kind of buzz, even after you've grown, dried and cured it.

So why does that happen? And what does it take for weed to give you the classic effects?

The key: decarboxylated cannabis

Once THCA is decarboxylated, it becomes THC, the compound behind weed's heady, uplifting effects. When you smoke or vape cannabis, it decarbs on the spot from the heat of the burning joint or the vaporizer.

In other words, THC exists in raw cannabis in its acid form, and it needs heat, after the plant is dried, to activate and become psychoactive. That's where this tongue-twister of a word comes in: decarboxylation.

What is decarboxylation?

Put simply, decarboxylation is the reaction that activates the cannabinoids in cannabis when you apply heat. So what exactly happens during decarboxylation?

Decarbing is crucial for activating the psychoactive compounds in cannabis and hemp. With smokable flower it happens on its own, since the flame does the work. For edibles, tinctures and salves, though, it's a more careful step that happens earlier in the process.

Decarbing means heating cannabis or hemp to activate the cannabinoids in the buds, trim, leaves or kief. That's what lets people feel the plant's unique, intoxicating effects through its active compounds.

What happens when you decarb cannabis?

Decarb methods mainly target cannabinoid acids, also known as inactive cannabinoids, which are found in the plant's trichomes. Trichomes are mostly on the cannabis flowers, but you'll also find smaller amounts on the leaves and stems.

When cannabis is heated, the molecular structure of those cannabinoid acids changes. During decarboxylation, the acids lose a carboxyl group (-COOH), released as carbon dioxide, while a hydrogen atom stays behind.

The chemistry: how THCA and CBDA get activated

Cannabinoid acids like THCA have 22 carbon atoms, 30 hydrogen atoms and four oxygen atoms. What leaves the molecule is one carbon atom and two oxygen atoms, as CO2. Once that's gone, THCA's molecular mass drops by about 12 percent and it becomes active THC.

Once activated, cannabinoids interact with the endocannabinoid system (ECS), a network of cannabinoid receptors found throughout the body, including the central and peripheral nervous systems. A handful of major and minor cannabinoids produce different effects in the body, ranging from euphoria to relaxation.

How do you decarb weed?

Before you decarb, the first step is to break the weed up into small pieces with a grinder or something similar.

Decarboxylation takes temperature and time: a certain amount of heat for a certain stretch. There's no single recipe for decarbing, CBD or THC, but our advice is to use the lowest temperature that does the job, so you keep as many terpenes and cannabinoids as possible, in the best shape. 

The best way to decarb weed is in the oven, for 45 to 50 minutes at 105 °C (220 °F). That said, the exact temperature depends on the kind of cannabis you've got.

You can also speed it up: about 30 minutes, raising the temperature to 120 °C (250 °F) max.

How to decarb weed in the oven, step by step

• Line a baking tray with parchment paper
• Spread the ground weed on it in a thin, even layer
• Preheat the oven to 105 °C (220 °F)
• Once it hits that temperature, slide in the tray with your ground cannabis
• Wait 45 to 50 minutes
• Take out your activated herb

Other ways to decarb cannabis:

Decarbing in the microwave

Some people swear by this method because it's fast. Still, be careful: it can degrade a lot of the compounds you're after.

The upside of the microwave is that there's less chance of scorching the herb than in the oven. Here's how:

• Grind the weed
• Spread it on a plate
• Put the plate in the microwave
• Heat it for 3 minutes at medium power
• Take out your decarbed cannabis, ready to go

Decarbing cannabis in a water bath

This method is less common, but it isn't complicated. To decarb cannabis in a water bath (basically a sous vide), you vacuum-seal it and "cook" it for an hour:

• Break up the weed by hand without grinding it; you want bigger pieces.
• Put the cannabis in a bag and seal it with a vacuum sealer.
• Bring a pot of water to a boil.
• Once it's boiling, turn down the heat so it holds at 95 °C (203 °F).
• Drop the bag into the pot.
• Wait an hour, and your herb is activated.

Do you always need to decarb cannabis?

Decarboxylation is a crucial step for getting high, but not all cannabis needs to be decarbed.
In humans, early research suggests raw, non-decarboxylated THCA may have a range of potential benefits:

• Anti-inflammatory
• Neuroprotective
• Anti-nausea
• Anticonvulsant
• Bronchodilator
• Metabolic regulation
• Stress relief

CBDA, found in raw plant material, is also being studied for possible anti-anxiety, anti-inflammatory, pain-relieving, anti-nausea and anticonvulsant properties. When it comes to decarbing, the THCA in the trichomes starts converting at around 104 °C (219 °F). In CBD-rich strains, CBDA starts converting at 118 °C (244 °F) and can take up to 90 minutes to fully decarboxylate.

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