What is purple weed is?

The Hemp Facts
August 17, 2023

If you’ve ever spent any time scanning websites devoted to  purple weed cannabis, you’ll undoubtedly have seen ridiculous-looking purple strains. You probably wondered, “Why have I never seen these in real life?”, and, “Are they even real?”. The good news is that, yes, they are real, and you can grow purple weed too!


Purple cannabis is cannabis with purple leaves, purple buds, or both. It looks amazing, and it’s hard to believe that it doesn’t have almost mystical effects, given iFts magical appearance. Though certain environmental conditions can trigger the expression of purple in cannabis, the most important factor when it comes to colouration is genetics. Some strains will go purple, others just won’t.


The phenomenon of purple weed is thanks to anthocyanins—a group of around 400 water-soluble pigments that can appear red, blue, or purple depending on the pH. If the pH is near neutral, as it should be, then any cannabis strain with an abundance of this pigment will likely end up with purple bud!

Anthocyanins aren’t actually produced by cannabis until the last few weeks of its life, where they can show up thanks to reduced amounts of chlorophyll, which would otherwise block them from view. A reduction in light exposure, which triggers photoperiod cannabis to bloom, results in less chlorophyll being produced. This can even be seen in cannabis plants that don’t produce an abundance of anthocyanins—with gold and orange hues often appearing within a plant’s last weeks before harvest.


All parts of the cannabis plant can change colour throughout its life cycle. Sometimes these are genetically predisposed changes, other times they are responses to the environment, and sometimes they are the symptoms of disease and pestilence.


Cannabis buds are the part of the plant with the greatest capability of donning a range of colours. When you consider that they are the plant’s flowers, then suddenly the display of colourful opulence seems less surprising.

In most cases, buds will be predominantly green. However, they can also take on hues of red, pink or purple. When you get a flower that isn’t green, it can be a very exciting moment.

However, it’s important to understand that certain colours appearing on buds can also indicate problems, such as bud rot. In these instances, they are likely to go brown and will begin to smell. Unless you’ve never seen weed before, it’s unlikely you’ll mistake this for an interesting, healthy colouration. Nevertheless, it’s still worth bearing in mind.


You may think that leaves are destined to be green. They are, after all, full of chlorophyll—the dominant pigment in cannabis—and chlorophyll is green. Well, in a way, you’re right. Except leaves start changing colour as autumn draws near. The temperature begins to drop, and plants inhibit chlorophyll production. Sound familiar? At the same time, anthocyanins will increase in quantity, thus causing cannabis leaves to change colour.

Anthocyanins can range from blue to purple, but there are other compounds that can cause different colourations too:

Much like the flowers, healthy processes aren’t the only ones that can cause leaves to change colour. The two things to look out for most are overwatering and overfeeding. Both of these cause symptoms such as yellowing, followed by wilting. Yellowing leaves can be a healthy, natural process toward the end of a plant’s life cycle, or a sign that something is wrong.


For most of their lives, trichomes are clear. These are the glands that grow on cannabis flowers and produce all of your favourite cannabinoids, such as THC and CBD, as well as terpenes, flavonoids, and other phytochemicals.

For cannabis growers, the trichome colour change is one of the most important parts of the entire process; it means harvest time is approaching! Once the trichomes begin to change from clear to milky, with some even turning amber, it’s time to snip off those buds and begin the post-harvest process.

The different colours of trichomes indicate the cannabinoid content and ratio within. A clear trichome is still developing and has not reached full potency.

A cloudy or milky trichome contains its peak amount of THCA (which converts to THC via the process of decarboxylation).

In an amber trichome, THCA has degraded into CBNA. CBNA decarboxylates into CBN, which creates a more couch-locked, less-psychotropic high.


Those little red-orange hairs all over your cannabis buds are called pistils. They are, in fact, the female sex organ of the plant. On most flowers, they are called stigmata. Their purpose is to catch pollen from males as it drifts by on the breeze.

They begin life white, and darken as the plant matures. On some strains, the overall amount of dark pistils can indicate the maturity of the whole plant; on others, they will continually replenish.

There are two reasons pistils turn dark. One is that they are old; another is that the plant is pollinated. In either situation, they turn dark when they are no longer needed. If you’re after a good crop of bud, you best hope they’ve turned dark because they’re getting old!


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