Harvest, drying and curing come at the very end of a crop and together take several weeks. They often have more effect on the final flower than most of the months of growing before them. This post covers three things: when to cut, why drying must be slow and even, and what happens to the flower during curing in a sealed jar.
When to cut: check the trichomes, not the day count
Trichomes are the tiny resin glands on the flowers. They hold most of the cannabinoids and aroma compounds. Seed companies print an estimated number of flowering days on the pack, but this is only a guide. The trichomes show when your own plants are actually ready.
Under a magnifier, trichomes change from clear to cloudy (milky white), and then some turn amber. You do not harvest on one exact day. There is a window of several days, and where you cut inside it changes the result:
- Earlier in the window: mostly cloudy trichomes and few amber ones. Growers usually describe this flower as lighter and more alert in effect.
- Later in the window: more amber trichomes. Growers usually describe this flower as heavier and more sedating.
If you grow for a licensed medical buyer, the buyer’s specification decides where in the window you harvest. Your personal preference does not.
What to do: Start checking the same few buds every 2–3 days, two weeks before the date on the seed pack. Use a pocket magnifier or a phone macro lens (see cheap macro setups for trichomes). Each time, note roughly how much is clear, cloudy and amber. The notes show you which way the trichomes are changing, so you can pick the harvest day before you pass your target.
Drying: take the water out slowly and evenly
After the cut, drying has one job. It removes water slowly and evenly, at a moderate temperature. If the flower dries too fast, growers commonly report that it keeps a green, grassy smell from chlorophyll (the green pigment in leaves), and that curing afterwards does not fully fix it.
Translator’s note: commonly cited drying targets are a cool room with moderate humidity, for one to two weeks, longer for dense buds. Sources differ on the exact numbers. In a Thai room without climate control, the temperature is often 30–35 °C. At that temperature, drying is too fast when the air is dry and too slow when the air is humid.
What to do: Put a digital thermometer and hygrometer (humidity meter) at bud height in the drying space. Write down the readings every morning and evening. Do this so you know your real drying conditions instead of guessing them. Bend a small stem each day. When it snaps instead of folding, the flower is usually ready for curing.
The first problem in this climate: humidity you cannot control
Thai and Southeast Asian air is usually very humid. Without a dedicated, closed drying space, you cannot run a controlled dry. A partly open room is worse because conditions keep changing, for example damp afternoons and drier nights.
Growers describe a defect that these swings cause, called case hardening. In dry periods, the outside of each bud dries quickly and forms a crust. In wet periods, the inside cannot release its water through that crust. The bud then feels dry outside but stays wet at the stem. If you jar it in that state, the trapped water spreads back through the bud, which raises the risk of mould inside the jar.
Translator’s note: in the rainy season, the outside air stays humid for weeks. A small closed space with a dehumidifier is easier to control than a large open room. Topic Drying Cannabis at 85–95% Ambient Humidity: Five Thai Setups compares practical options. Topic Dehumidifier and Air-Conditioner Sizing for a Thai Flowering Room explains why an air conditioner alone may not bring humidity down far enough. In a power cut, the dehumidifier stops and humidity in a closed space rises quickly. A hygrometer with min/max memory shows you what happened overnight.
What to do: Before you change your whole drying setup, test it with one small batch of plants. Record the minimum and maximum humidity every day for the whole dry. If the gap is large, add a dehumidifier or move to a smaller closed space before your next harvest. Before jarring, cut one bud open and press the stem. Do this to confirm that the inside is as dry as the outside.
The second problem: grey mould in the drying room
Botrytis (grey mould) is a fungus that rots buds from the inside. It often shows first as grey fuzz or brown, soft patches. A crop that stays clean through the whole grow can still be lost in the drying room. That means airflow and daily inspection continue after the cut.
Translator’s note: dense buds hanging in still, humid air are the highest risk, and this is common in the Thai rainy season. Mould also brings a toxin risk, explained in Mycotoxins on Cannabis Flower.
What to do: Keep the air moving gently around the hanging flowers. Do not blow a fan straight onto them, because that dries the outside too fast. Check the densest buds every day, and look inside them as well as at the surface. Bag any infected bud right away, take it out of the room, and record where it was hanging. These records show you which spots in the room stay too damp.
Curing: what changes inside the sealed jar
Curing means keeping dried flower in sealed containers for a period of weeks. Inside the jar, the moisture left in each bud spreads evenly from the stem to the surface. That is why the flower has to be evenly dry before jarring. A bud with a wet stem only spreads that water into the jar.
Translator’s note: many growers put a small hygrometer in one jar, aim for about 58–62% relative humidity inside, and open the jars briefly if humidity rises. A cure of a few weeks is commonly recommended.
What to do: Fill one test jar first and read its hygrometer every day for the first week. Rising humidity means the flower went in too wet. Take it out to dry further before you jar the rest of the batch.
Licensed farms: keep records of drying conditions
Translator’s note: cannabis flower is a controlled herb in Thailand. This is set by the Notification of the Ministry of Public Health Re: Controlled Herbs (Cannabis), B.E. 2568, in force since 26 June 2025. If you hold a licence, keep your daily temperature and humidity notes as part of your batch records. Topic Good Agricultural and Collection Practice for Cannabis: Records, Farm Site, Crop and Drying explains what drying records cover.
Where to start reading
- Harvest, Drying and Curing: The Science Behind Quality: the background to every step above.
- The Botrytis (grey mould) topic linked in the mould section above, for prevention, early detection and emergency response.
Ask your question below
Post your drying setup, your room’s temperature and humidity readings, and photos of the trichomes or of any suspect buds as a reply under this topic. Readings and photos let other growers give you a specific answer.