Short answer. Cure the bud's moisture, not the jar's air. Put properly dried buds (small stems snap, aw ~0.60–0.65) loosely into airtight jars about ¾ full, with a salt-tested hygrometer. Keep jars dark at 15–21 °C (60–70 °F). Burp (open for 10–15 minutes) once or twice a day for the first week, then every few days, then weekly. Start with the buds at about aw 0.62–0.65 and let them fall slowly towards 0.55–0.58 over the cure: curing is a steady decline, not a constant hold. The jar's RH tells you the bud's aw only once the sealed jar has equilibrated (aw ≈ RH / 100). If an equilibrated jar reads above ~65–68 %, take the buds out and dry them more; ASTM notes aw above 0.68 calls for further drying [1][2]. Cure 2–8 weeks. Smoother smoke and rounder aroma are widely reported, but the chemistry of curing is Grower practice, not well studied.
House position: a cure never fixes a bad dry. Long cures help, within reason. But a hay smell means bacteria, over-drying, or drying too fast, and it never truly comes out. Get the dry right first.
House position: curing is a slow decline, not a hold. A cure slowly reduces the bud's moisture content and water activity over time; it doesn't hold them constant. Start at the top of the range (aw ~0.62–0.65) and let it fall steadily towards ~0.55–0.58 over the weeks. Humidity packs are a marketing gimmick. The only data saying they help is a pack maker's own test, and in the founder's experience they cost you terpenes. If a jar has gone too dry, put a fresh, slightly moister bud in with it for a day instead. (Packs vs a fresh bud vs nothing is an open GenetixBay trial.)
The bud, not the jar: moisture content and water activity
What you are curing is the bud. Two numbers describe its water:
- Moisture content (MC): how much water is in it, as % of its weight (w/w).
- Water activity (aw): how "available" that water is, from 0 to 1.0. It is what mould and bacteria respond to, and it is what the ASTM D8197 range (0.55–0.65) is written in [1].
Jar RH is only a proxy. A hygrometer measures the air in the jar, not the bud. Once a sealed jar has equilibrated (the reading has stopped moving, usually after 12–24 h undisturbed), the air and the bud agree, and aw ≈ equilibrium RH / 100: a stable 60 % means the bud is at about aw 0.60. Read it straight after burping or after you've just filled the jar and it tells you about the air, not the flower. Hygrometers also drift; salt-test yours.
What that means in moisture. At aw 0.55–0.65, cured flower holds roughly 8–12 % water by weightbeing reviewed [5]. The exact link between aw and MC (the moisture sorption isotherm) differs a little by cultivar and bud density, which is why aw, not %, is the standard.
How to check the bud
| Check | How | What "ready" looks like |
|---|---|---|
| Stem snap | Bend a small stem from inside the jar | Snaps cleanly with a little fibre; a bend means too wet, a powdery crumble means too dry |
| Equilibrated hygrometer | Seal the jar, leave it untouched 12–24 h, then read | Stable 55–65 % (aw 0.55–0.65); start the cure at the top of that, let it fall slowly |
| Weight | Weigh a tagged branch or a jar's buds wet, then track | Finished flower ends at roughly 20–25 % of its wet weightbeing reviewed; a slow, steady fall in weight over the cure is the "decline" you want |
| Feel | Squeeze a bud gently | Springs back; not spongy, not crispy |
A dedicated water-activity meter is the gold standard, but an equilibrated, salt-tested hygrometer gets you close enough at home.
What's happening
- Moisture equalisation: after drying, the core of a bud is wetter than the outside. Sealed, the moisture redistributes; burping releases the excess so the jar doesn't climb into mould territory.
- Chlorophyll and sugars: growers attribute the loss of a fresh "green" note to slow breakdown of chlorophyll and starches during a slow dry and cure. This is plausible but not well documented in cannabis (Grower practice).
- Hay smell: a true hay smell comes from bacteria, over-drying or drying too fast. The cure won't remove it (house position).
- Terpenes: volatile monoterpenes keep escaping during drying and storage, with sesquiterpenes becoming a larger share [3]. Terpenes are more affected by drying method than by storage in hemp; cannabinoids more by storage [4]. A cure doesn't add terpenes; it limits further loss and lets aroma settle.
Numbers that matter
| Parameter | Target |
|---|---|
| Jar fill | ~¾ full, loose |
| Bud aw (equilibrated jar RH / 100) | Start 0.62–0.65, decline slowly to 0.55–0.58 (0.55–0.65 overall) [1] |
| Bud moisture content | ~8–12 % w/w at that aw (method dependent)being reviewed [5] |
| Too wet | Equilibrated jar > 65–68 % → remove and dry [2] |
| Too dry | < 55 % → add a fresh, slightly moister bud for a day; no humidity packs |
| Finished weight | Roughly 20–25 % of wet weightbeing reviewed |
| Temperature | 15–21 °C (60–70 °F) |
| Burping | Week 1: 1–2×/day; week 2: every 2–3 days; after: weekly |
| Duration | 2 weeks minimum; 4–8 weeks common |
- Freeze drying and water curing: Contested; not recommended (see drying).
How to do it
- Check dryness on the bud: stems snap, then seal a sample jar with a hygrometer for 12–24 h untouched. Only that equilibrated reading counts.
- Fill jars ¾, add a calibrated mini hygrometer, seal, label with date and cultivar.
- Burp on schedule; sniff each time. An ammonia or musty smell = too wet, mould risk: spread buds out to dry immediately.
- Don't add humidity packs: they're a marketing gimmick (house position). Let the bud's aw drift down slowly, reading the jar only after it has sat sealed long enough to equilibrate; if it drops below ~55 %, add a fresh bud for a day.
- Track weight: weigh each jar's buds when you fill it and again each week. Small, steady losses mean the cure is declining as it should; a gain means moisture got in.
- After the cure, move to long-term storage.
Greenleaf's standing challenge: darkness before harvest. Putting plants in 24–72 h of darkness before the chop is a Myth, and the founder's verdict is "complete and utter nonsense": why cut photosynthesis in the most critical part of the life cycle, while the plant is still finishing its resin? For more than 20 years the founder has offered a standing challenge: find a peer-reviewed study showing a benefit (not a single-plant study, not biased or skewed) and a 50-pack of seeds is yours, no questions asked. Nobody has claimed it.
Common mistakes
- Jarring buds too wet (the jar spikes to 75 %+ overnight).
- Packing jars tight.
- Leaving jars in sunlight.
- Expecting the cure to fix a 3-day hot dry, or a hay smell. It won't.
- Plastic bags (static strips trichomes; poor vapour barrier).
- Reading the hygrometer right after burping and calling it the bud's humidity. Only an equilibrated jar tells you about the bud.
- Trying to hold the jar at one number for months.
Evidence
The aw range and the "dry further above 0.68" rule are Established standards [1][2]. Terpene loss over time is Supported [3][4]. Burping schedules, duration and sensory claims are Grower practice. aw ≈ equilibrium RH / 100 is the definition of water activity, so an equilibrated jar reading is a fair proxy; the moisture-content figure for a given aw depends on the measuring method (Supported by one lab's method-validation data [5]). A slowly declining bud aw rather than a constant hold: house position (Grower practice). Humidity packs are a marketing gimmick (house position). The only pro-pack data is the manufacturer's own: a pack maker reports higher terpene levels with its packs in a company-commissioned jar test (not peer reviewed), and we have not found an independent study either way. ASTM D8197 lists salt-based sachets as one way to bring under-range flower back up [2]; that is a storage-spec convenience, not evidence that packs improve flower.being reviewed Freeze drying and water curing: Contested, not recommended.
