Cannabinoids in detail: the difference between CBD, CBG and THC

The difference between CBD, CBG and THC lies in their chemical structure, in the amount a hemp plant produces and in their legal status. All three cannabinoids are formed in the plant from the same precursor, cannabigerolic acid (CBGA). In Switzerland, a limit only applies to THC: hemp with a total THC content of 1.0 percent or more is a narcotic. CBD and CBG are not listed in the directory of narcotics. The abbreviations stand for cannabidiol (CBD), cannabigerol (CBG) and tetrahydrocannabinol (THC).

CBD, CBG and THC at a glance

The table sums up the key facts. The figures on the range come from the product details of the flowers at Green Passion.

What is CBG?

CBG is short for cannabigerol. The hemp plant first produces the acid form CBGA. During flowering, it uses this to build the other cannabinoids. That is why CBG is often called the mother of cannabinoids. In ripe flowers of most strains, only a little CBGA is left, because most of it has already been converted by harvest time.

A flower with a lot of CBG requires genetics in which this conversion hardly takes place. Such strains are rare. Our CBG flowers grown in Switzerland come from the Freedom Flower strain, which according to the product details contains around 10% CBG. You can find more about the origin and chemistry of cannabigerol in the article What is CBG.

CBGA as the common precursor of CBD and THC

In the plant, cannabinoids first exist as acids. The A at the end of the abbreviation stands for acid. It all starts with CBGA. Certain enzymes, the synthases, convert CBGA into other acids. These processes are described in a review by Li and colleagues (2024) in the journal Molecules:

• THCA synthase converts CBGA into tetrahydrocannabinolic acid (THCA).
• CBDA synthase converts CBGA into cannabidiolic acid (CBDA).
• CBCA synthase converts CBGA into cannabichromenic acid (CBCA), the precursor of CBC.

Decarboxylation turns the acids into the neutral forms CBD, THC and CBG. In this process, a carboxyl group splits off, mainly through heat and over time. Which synthase dominates in a plant is determined by its genetics. This explains why one strain produces a lot of CBD and another a lot of THC, even though both start with the same raw material. A strain with a lot of CBD therefore usually has little THC, because both pathways use the same precursor.

Difference between CBD and CBG

CBD and CBG differ mainly in quantity and in their position in the plant's metabolism. CBG is the precursor, CBD is a product formed from it. In CBD strains, CBD is the main cannabinoid, while CBG only occurs as a minor cannabinoid. As the table above shows, the CBG content of the CBD flowers in the range is far below their CBD content.

The molecules are also built differently. CBG has the molecular formula C21H32O2, which means two more hydrogen atoms than CBD. In CBG, the side chain is open and does not form an additional ring. In CBD, part of this chain has closed to form a carbon ring. How this step takes place in the plant is explained in the section on the precursor CBGA.

As a buyer, you can see the difference on the label. A CBG flower is labelled with a high CBG value and little CBD. With a CBD flower, it is the other way round.

Difference between CBD and THC in chemical structure

CBD and THC have the same molecular formula, C21H30O2. Both molecules therefore consist of the same atoms in the same number. Chemists call such substances isomers. The difference lies in the arrangement: THC has an additional closed ring with an oxygen atom. In CBD, this ring is open.

Legally, however, the two isomers are treated completely differently. In Switzerland, THC is controlled as a narcotic, CBD is not. In the plant, too, both are formed from CBGA along separate pathways, as described above in the section on the precursor.

CBD to THC ratio in industrial hemp strains

Swiss CBD hemp is bred for a high CBD content and a low THC content. It is not completely free of THC, because CBD strains also produce some THCA. The ratio is easy to see in the product details of our own range:

• Passion Kush: 16% CBD, 0.9% THC
• Amnesia Haze: 16% CBD, 0.8% THC
• Maui Wowy: 18% CBD, 0.9% THC
• Gorilla Smack: 19% CBD, 0.7% THC

In the CBD strains, there are about 18 to 27 parts CBD for every 1 part THC. The content depends mainly on the strain and less on the growing method, as we show in our comparison of indoor and outdoor flowers. You can find all strains with their values under CBD flowers.

Legal status of CBD, CBG and THC in Switzerland

The relevant law is the FDHA Narcotics Directory Ordinance (BetmVV-EDI, SR 812.121.11, as of 13 March 2026). Directory d lists under the entry cannabis: hemp plants or parts of them with an average total THC content of at least 1.0 percent are narcotics. The same applies to preparations with at least 1.0 percent total THC.

Cannabidiol and cannabigerol are not listed as separate entries in this ordinance. So there is no specific limit for CBD and CBG. For hemp flowers, the total THC content alone determines whether they fall under narcotics law. Depending on the type of product, other laws may also apply, for example for food or cosmetics. You can read more about the 1 percent limit in the article on the 1 percent rule in Switzerland.

Other limits apply abroad. In Germany, the limit for industrial hemp is 0.3 percent THC (KCanG § 1 Nr. 9). Anyone travelling with hemp products must check the rules of the destination country.

How CBD, CBG and THC content is declared

On hemp flowers, the content is given as a percentage of weight. A value of 16% CBD means that 1 gram of flower contains around 160 mg of CBD. Because hemp is a natural product, the values vary slightly from harvest to harvest.

For THC, the total THC content is what counts. The Swiss Federal Supreme Court has described it as the sum of THC and THC carboxylic acid (BGE 145 IV 513). The acid form THCA is therefore included, even though it is not yet present as THC in the fresh flower. A product with 0.2% free THC but a lot of THCA can therefore still be above the limit.

At Green Passion, the product page of every flower shows the CBD, THC and CBG content in percent. This lets you compare strains directly. The flowers are declared with a THC content below 1 percent and are only sold to people aged 18 and over.