Flavonoids: the compounds that give CBD flowers their colour

When people talk about CBD flowers, they think of CBD and of the terpenes that create the scent. Hemp also contains a third, less familiar family of compounds: flavonoids. They have no smell, but they contribute to the colour of the buds and are part of the chemistry that makes each strain different from the others.

What are flavonoids?

Flavonoids are polyphenols found in almost all plants: in fruit, vegetables, tea and cocoa. The name comes from the Latin flavus, yellow, because many of these compounds are yellow pigments. In the plant they contribute to the colour of leaves and flowers and protect it from ultraviolet rays.

The flavonoids in hemp

In hemp, flavonoids are found mainly in the leaves and flower heads. The most common ones belong to two groups, flavones and flavonols:

• Apigenin and luteolin: flavones found in many plants, for example chamomile and parsley.
• Quercetin and kaempferol: flavonols that also occur in onions, apples and capers.
• Orientin and vitexin: flavones bound to a sugar molecule, also described in hemp.

Cannflavins, typical of cannabis

Some flavonoids occur almost only in cannabis. These are cannflavins A and B, described in the mid-1980s by the researcher Marilyn Barrett in London; cannflavin C was added later. In 2019 a team at the University of Guelph in Canada described in the journal Phytochemistry the genes the plant uses to make them. Cannflavins are present in the plant only in very small amounts.

Research on these compounds continues: in 2025 a study from Stellenbosch University identified 79 phenolic compounds in cannabis, 25 of them never reported before, as we report in our news on the flavoalkaloids of cannabis.

Why some buds turn purple

The green of the buds comes from chlorophyll. Anthocyanins, a group of flavonoids, produce purple, red and blue tones instead. In many strains they stay hidden by the green; when the plant makes less chlorophyll at the end of the season, they can show through. The colour depends on genetics and growing conditions: that is why a strain such as Purple Haze can show purple hues, but not always to the same degree.

Colour says nothing about the CBD content: a purple bud does not necessarily contain more or less CBD than a green one. To judge a flower, what counts is the overall picture of look, trichomes, scent and moisture, as we explain in how to recognise quality CBD flowers.

Flavonoids and terpenes: the differences

• Terpenes: they are volatile, evaporate easily and are mainly responsible for the scent. See the guide on terpenes in CBD flowers.
• Flavonoids: they are not volatile, so you cannot smell them; they mainly contribute to the colour of the plant.
• Cannabinoids: such as CBD, they are the third family of compounds and are the ones stated as a percentage on the pack.

The aroma of cannabis does not depend on terpenes alone either: some sulphur compounds contribute to its typical smell, as we report in our news on a new compound beyond terpenes.

Frequently asked questions

Is the flavonoid content shown on the pack?

No. The pack shows the CBD and THC content. Flavonoids require a specific laboratory analysis and are not measured for every batch.

Are flavonoids found only in hemp?

No, they occur in almost all plants. Only some, such as cannflavins, are typical of cannabis.

How do you preserve the colour and quality of the flowers?

In the dark, somewhere cool and in an airtight container, because light and heat change both colour and aroma over time. Read how to store CBD flowers.

All strains and their characteristics are described in the guide to CBD flower strains and in the CBD flowers collection, sale to adults only.