Last checked: October 27, 2026
Crack a jar, and every so often the buds inside aren't green at all. They're plum, violet, almost black at the edges. Purple weed stops people mid-sentence, and the question "why is some weed purple" gets asked at every counter in Brampton. Blouds Dispensary, at 117 Queen St W in downtown Brampton, west of Main St, lays out the plant science for adults 19+. Short version: it's pigment. Long version is more fun.
The pigment doing the work
Plants paint themselves with a handful of pigment families. Chlorophyll is the green one, and it dominates most of a cannabis plant's life. Anthocyanins are another family: the same group of compounds that colours blueberries, red cabbage and autumn leaves. In cannabis, anthocyanins can show up in the leaves, the sugar leaves around the bud, the calyxes and even the stems.
When there's enough anthocyanin, and the green backs off, purple shows through. That's the whole trick. Purple weed isn't dyed, it isn't a separate species, and it isn't a special category on a label.
Genetics first, weather second
Here's the part the internet usually oversimplifies. Cold nights alone don't explain purple. The plant's genetics matter, and temperature nudges the colour up or down.
Researchers have tested the temperature side. In a 2025 study in the Journal of Cannabis Research, they grew an inbred cannabis line that reliably turns purple at a range of temperatures. Anthocyanin levels in the flowers peaked at constant temperatures of 8°C and 15°C, and dropped off at both the coldest (0.5°C) and warmest (22°C) settings they tested. The same paper found that CBD content and flower weight tracked the plant's maturity, not the temperature swing.
What that means for you, standing at a counter: colour tells you about pigment chemistry and growing conditions. It's a look, not a scorecard.
What purple weed is NOT
Quick corrections, because the myths travel fast:
- Not a strain category. Lots of different cultivars can show purple. Colour alone doesn't tell you which one you're looking at.
- Not a THC signal. The only reliable numbers are the Total THC and Total CBD values printed on a legal label. Colour isn't on that list.
- Not a rarity badge. Purple shows up across the market. No colour makes a bud more legitimate.
- Not always natural-looking. If a bud looks painted, glittery or sprayed, that's a red flag. Legal dried cannabis is just the plant, trimmed, dried and packaged.
Purple weed vs other colours in the jar
| What you see | What's usually going on |
|---|---|
| Deep green | Chlorophyll still dominant |
| Purple or violet | Anthocyanin pigment showing through |
| Orange or rust "hairs" | Pistils that changed colour as the flower matured |
| White or silvery frost | Trichomes, the resin glands on the surface |
| Brown, crumbly patches | Worth a closer look: could be age, rough handling or poor storage |
Notice that only one of those rows is about purple. A bud can be purple and frosty and covered in orange pistils at the same time. Each colour has its own cause.
Why purple weed looks darker in the bag
Under the bright lights at a counter, purple can look nearly black. In daylight it might read as plum or magenta. Lighting changes what you see, and so does the trim: buds trimmed tight show more calyx colour, while buds with more sugar leaf left on can show purple leaf tips around a green core.
That's why two jars labelled with the same product type can look totally different. Same plant family, different grow, different trim, different light.
Reading the label on purple flower
Colour gets your attention. The label gets you facts. On any legal package of dried cannabis, check:
- Product class: dried cannabis.
- Total THC and Total CBD values.
- Net weight.
- Packaging date.
- The standard health warning.
If the product name says "purple" something, that's a product name, not a guarantee of colour. Look at the flower itself if the package allows it, and judge the colour with your own eyes.
Storing purple weed
Pigment doesn't need special care. Purple flower stores the same way any dried cannabis does: in its original sealed, labelled container, in a cool, dark spot, out of reach of kids and pets. Light and heat over time can dull colour in any plant material, so a drawer beats a sunny windowsill.
Purple weed questions people ask in downtown Brampton
Is purple weed a different plant? No. It's cannabis that happens to express a lot of anthocyanin pigment.
Can any plant turn purple if it's grown cold? Don't count on it. The 2025 study used a line already bred to turn purple, and temperature pushed its colour up or down. Genetics and conditions work together.
Does purple mean it was grown outdoors? Not necessarily. Indoor growers can control temperature too. The label won't usually tell you, and colour alone can't either.
Is there a "best" purple? We won't rank colours. Pick by the label details that matter to you, and treat colour as a bonus.
The takeaway
So, why is some weed purple? Because some cannabis plants carry the genes to make anthocyanins, and growing conditions such as temperature can turn that colour up or down. Purple weed is a visual trait, not a quality grade. Enjoy the look, then read the label.
Planning a stop? The Blouds visit page has the trip details. Blouds Dispensary is for adults 19 and over. Bring government-issued photo ID.