Short answer
Fill curing jars about ¾ full, loosely, so the buds aren't crushed and the air can move when you burp. Too full traps wet pockets. Too empty gives a big air space that swings the humidity. After the cure, fill storage jars fuller. Grower practice.
Why
A cure is a slow decline in moisture. The bud's water activity should start around 0.62–0.65 and fall towards 0.55–0.58 over the weeks, inside the ASTM range of 0.55–0.65 [1]. Loose buds at about ¾ full give up their excess water evenly when you burp.
Packed jars stay wet in the middle. Moisture in a crushed mass of buds can't reach the air, and above water activity 0.68 flower needs more drying [2]. That is where mould and ammonia smells start.
The hygrometer needs room to read. Once a sealed jar has equilibrated, its RH divided by 100 equals the bud's water activity [1]. With a sensible fill it reflects the buds, not one wet corner.
Storage is different. After curing, the job is to slow oxidation: air turns THC into CBN in storage, and light destroys THC [3]. A fuller, airtight jar kept in the dark limits both.
The numbers
| Stage | Fill level | Why |
|---|---|---|
| Curing (weeks 1–8) | About ¾, loose | Air to burp, buds uncrushed |
| Storage after the cure | Fuller, still not crushed | Less air, less oxidation [3] |
| Practical jar size | 0.5–1 L glass | Equalises overnight, limits losses |
| Equilibrated jar RH | 55–65% | aw 0.55–0.65 [1] |
What to do
- Jar buds only when the stems snap and a sealed sample reads a stable 58–65% RH.
- Drop buds in loosely to about ¾ full. Don't press them down.
- Add a calibrated mini hygrometer, seal the jar, and label it with cultivar and date.
- Burp for 10–15 minutes once or twice a day in week 1, every 2–3 days in week 2, then weekly.
- Shake each jar gently when you burp so the buds turn.
- After the cure, combine jars into fuller ones and store them cool and dark.
Common mistakes
- Pressing buds down to fit one more in.
- One giant jar for the whole harvest.
- Reading the hygrometer straight after opening.
- Storing jars in sunlight.
Related
- Full article: Curing and burping
- Answers: mould in jars · ammonia smell · buds lost their smell
- Article: long-term storage
- Terms: curing jar · burping
