What are trichomes on weed, and why do they matter?

What are trichomes?

Plants grow all kinds of tiny surface structures called trichomes, like the fuzz on many leaves and the stinging hairs on a nettle. Cannabis grows a special kind, glandular trichomes, that produce a sticky resin. That resin is where the plant makes and stores its cannabinoids, including THC, and its terpenes, the aroma compounds. The frosty, crystal-like coating you see on a good bud is thousands of these glands.

You can see the biggest ones with the naked eye. With a cheap magnifier they look like little mushrooms: a clear or milky ball on a stalk.

What do trichomes do?

For the plant, trichomes are protection. On many plants, these tiny hairs and glands help keep insects and animals away, shade the plant from strong sun, and slow water loss. In cannabis, some of the glands make bitter compounds that put off grazing animals.

For you, they are the whole point. A University of British Columbia study found that the large, mushroom-shaped glands are the richest source of the compounds that become THC and CBD, and of terpenes. In the university's words, flowers with the most of them "pack the biggest cannabinoid and fragrance punch." The leaves hold far less. So frostier flower tends to be stronger, all else being equal.

The three types of cannabis trichomes

When people talk about trichomes on weed, they mean the stalked kind.

Trichomes vs. mold

Beginners mix these up in both directions. The quick test: trichomes sparkle, sit evenly over the whole bud, and look like tiny glass beads under a light. Mold is dull, fuzzy or web-like, grows in patches, often in the creases or near the stem, and smells musty. If it glitters, it's trichomes. If it looks like dryer lint, it's not. The moldy weed guide has the full comparison and what to do.

What is kief?

Kief is trichomes that have broken off the flower. Dried buds are brittle, so every time you handle or grind them, some glands fall away as a fine, pale powder. A grinder with a screen and a bottom chamber (a "kief catcher") collects it. Larger amounts are made by sifting flower over a fine mesh, which is why kief is also called dry sift. Pressed with heat, kief becomes hash. The word comes from Arabic, where it means pleasure.

People sprinkle kief on a bowl, roll it into a joint, or heat it and cook with it like flower. It takes a lot of flower to collect a little kief, roughly 7 to 14 grams of flower for a gram of kief. So for most people it's a bonus from the grinder.

Is kief stronger than weed?

Yes, by weight, because it's the glands without the plant material around them. In one published test, kief sifted from frozen flower held about 2 to 5 times the cannabinoids of the flower it came from, depending on the plant. In one trial, that was about 61% against about 25%. Kief sifted from dried flower in the same study had bits of leaf in it, and grinder kief is likely similar. It's still stronger than the bud. Health Canada lists kief with the high-THC extracts it tells new and occasional users to avoid. Treat a pinch of kief like a lot more than a pinch of flower. If you overdo it, the too high page tells you what to do. If you're new, the first-time guide comes first.

Clear, cloudy and amber trichomes

You'll see charts of trichome colors online. Those are harvest cues for growers: the glands start clear, turn cloudy (milky) as they fill with resin, and go amber as they age. By the time flower is dried and sitting in a jar, that moment has passed.

For a buyer, two things are worth knowing. First, color doesn't tell you strength. The THC percent on the label does. Second, the common claim that amber trichomes mean a sleepier high is popular but not proven. What you can judge by eye is coverage. A bud thick with intact, glittering glands has usually been handled and stored well. One that looks dull and bare may not have been.

How to keep trichomes on your weed

• Handle buds gently. Every squeeze and shake knocks glands off. Pick up buds by the stem, and keep them whole until you use them.
• Grind right before you use it. Ground flower loses its aroma compounds faster than whole buds; a storage study found lower terpene levels in every ground sample compared with whole ones.
• Keep it cool, dark and sealed. Heat and light break down THC and terpenes over time. The storage guide covers the jar, the humidity and how long flower keeps.
• Know what's in the catcher. If your grinder has one, that powder is the trichomes you knocked loose. It's concentrated, so it's much stronger than the flower.

Words you'll hear

• Frost, sugar, crystals: trichomes, as seen from a distance.
• Resin: the sticky stuff inside the glands. Also what builds up in a pipe.
• Kief, dry sift, pollen: loose trichomes. "Pollen" is slang; it isn't real pollen.
• Hash: kief pressed into a solid, or trichomes collected with ice water and pressed. See bubble hash.
• Loupe: a small magnifier. Budtenders (dispensary staff) use one to show off a bud's trichomes.
• Live resin, live rosin: concentrates made from fresh-frozen plants. See live resin vs. live rosin.

Common questions