How to Decarb Weed

Making edibles at home can be a customizable alternative to buying products from dispensaries, with DIYers able to tailor their edibles to their own tastes and dietary requirements.

But before cannabis can be added into a brownie mix or a cookie batter, it is first necessary to decarboxylate it.

How to decarboxylate weed in an oven

Materials

• Baking sheet
• Parchment paper, aluminum foil, or reusable silicone baking mat
• Oven
• Cannabis flower
• Oven thermometer (optional)
• Cannabis grinder (optional)

Directions

1. Position the oven rack to the middle of the oven and preheat to 220°F (approx. 105°C).
2. Line a baking sheet with parchment paper, foil, or another non-stick baking liner and lightly crumble or grind the cannabis flower onto the sheet. Be aware that too small a grind may increase the risk of burning.
3. Place the baking sheet on the center rack of the oven. Bake for around 30 minutes, stirring halfway through.
4. When the cannabis looks lightly toasted and golden brown, remove from the oven and leave to cool for at least 30 minutes.
5. With the decarboxylated cannabis material now cool enough to handle, this can be added to a butter or oil base for infusion. Alternatively, transfer to an airtight container for storage and future use.

It is worth bearing in mind that every brand of oven is different and the temperature indicated on the dial may not be exactly equivalent to the actual temperature inside the oven.

To make sure that these temperature fluctuations won’t burn the cannabis flower, it can be a good idea to check on the cannabis regularly throughout the decarboxylation process. If the flower is browning too quickly, reduce the temperature. Using an oven thermometer can also help identify if the oven naturally runs slightly hotter or cooler than indicated on the dial, so that this can be adjusted accordingly.

For similar temperature control reasons, cannabis should not be decarboxylated in a microwave, though a small controllable toaster oven may be suitable if access to a full-sized oven is not possible.

What is decarboxylation?

Decarboxylation is the scientific name for when a carboxyl group is removed from a molecule’s chemical structure, releasing carbon dioxide in the process.

In the case of cannabis, it is decarboxylation that causes the molecule tetrahydrocannabinolic acid (THCA) to lose its acidic part and form the neutral compound tetrahydrocannabinol (THC). Importantly, THC is intoxicating but THCA is not, meaning that any cannabis plant material needs to be decarboxylated first in order to deliver the classic cannabis high.

Decarboxylation doesn’t just affect THCA; there are a number of other important acidic cannabinoids that are decarboxylated when cannabis is heated, such as cannabidiolic acid (CBDA), which goes on to form cannabidiol (CBD). CBD has been linked to improvements in inflammation, anxiety, and a number of other common physical conditions, so it can be important that cannabis is properly decarboxylated to generate as much CBD as possible.

The decarboxylation of cannabis flower happens naturally over time when exposed to ambient heat, and this can be accelerated slightly during drying and curing. When cannabis flower is smoked or vaped, the high temperatures involved near-instantly decarboxylate the precursor compounds in weed.

Cannabis edibles, though, are normally made by creating a cannabis-infused oil or butter from cannabis buds, and this infused fat can then be used to make an edible. But this infusion process rarely involves enough heat for complete decarboxylation. So, before doing anything else, these buds need to be decarboxylated.

How long to decarb weed

Using an oven is a perfectly suitable way of decarboxylating cannabis at home. However, care needs to be taken not to leave the cannabis in the oven for too long or else the terpenes and neutral cannabinoids may start to be burned off. Similarly, too short a time might mean incomplete conversion, and losing out on a little bang for your buck.

Generally, a decarboxylation time of between 30-35 minutes should be satisfactory for home decarboxylation. This allows for a slow enough roast at a moderate temperature so that there is minimal risk of burning the cannabis flower.

What temperature to decarb at?

A recent kinetics study found that the conversion of THCA into THC can actually proceed incredibly quickly, with peak conversion achieved easily at temperatures of around 320°F (160°C) for seven minutes. However, a much slower approach is needed to maximize CBD concentrations, around 175°F (80°C) for 25 hours.

Understandably, it is a little impractical to run a home oven for 25 hours straight. Given the protection that CBD is thought to offer against some of the negative side effects of THC, many consumers will also want to create a more balanced decarboxylation.

Based on data from a 2016 study on decarboxylation, the below table shows a range of possible temperature and time combinations for good decarboxylation.