Most growers understand that curing improves cannabis. Fewer understand WHY. The standard advice — "put it in jars and burp them" — describes the procedure without explaining the biochemistry. When you understand what's actually happening inside the jar, you make better decisions about humidity, temperature, duration, and troubleshooting.
Curing is not slow drying. It's a controlled environment where specific biochemical processes transform rough, hay-smelling dried flower into smooth, aromatic, properly burning cannabis.
What happens during curing
Chlorophyll degradation
Fresh-dried cannabis smells like hay or grass. That smell is chlorophyll — the green pigment that powers photosynthesis. Chlorophyll has a harsh, vegetal taste when combusted.
During curing, chlorophyll breaks down through enzymatic degradation:
- Chlorophyllase enzymes (still active in dried tissue at moderate moisture levels) cleave the phytol tail from the chlorophyll molecule
- The remaining chlorophyllide continues degrading into colorless pheophytins
- The process requires moisture (which is why jar curing works — the sealed environment maintains humidity) and time
Timeline: major chlorophyll breakdown occurs in the first 2–3 weeks of curing. This is why the hay smell fades and the strain's true terpene aroma emerges during this period.
Too dry = no cure. If you over-dried the flower (below 55% RH in the jar), the enzymes denature and chlorophyll degradation stops. The hay taste persists permanently. This is the most common curing failure.
Starch and sugar conversion
Living cannabis stores energy as starch in the buds and leaves. During curing, residual amylase enzymes convert starch into simple sugars, which further break down:
- Starch → maltose → glucose → consumed by aerobic bacteria in the jar
- The removal of starches and sugars produces a smoother, cleaner smoke
- This is part of why cured cannabis burns more evenly (less unburned carbon residue from starches)
Terpene preservation and transformation
Terpenes are volatile — they evaporate. The curing environment (sealed jar, 58–62% RH, 60–68°F) slows terpene evaporation while allowing enzymatic terpene modification:
- Some terpene precursors continue converting to active terpenes during curing
- The sealed jar prevents the rapid terpene loss that occurs in open-air drying
- Cool temperatures slow evaporation (terpenes evaporate faster at higher temperatures)
This is why cured cannabis smells stronger than fresh-dried: the chlorophyll smell fades (unmasking the terpenes) while the sealed environment retains them.
Minor cannabinoid maturation
A small amount of THC-to-CBN conversion occurs during curing (the same process that happens on the plant during late flower). The effect is minor — perhaps a 1–3% shift — but contributes to the "smoother" effect profile that well-cured cannabis is known for.
THCA also continues decarboxylating very slowly at room temperature, though the rate is negligible compared to heat decarboxylation.
The curing protocol
Prerequisites
The flower must be properly dried first. Curing starts AFTER drying, not instead of it:
- Dried to 60–65% moisture content
- Small stems snap (don't bend) when flexed
- The outside of buds feels dry to the touch but isn't crispy
- This typically takes 7–14 days of hanging in 60°F / 60% RH
See our drying guide.
Week-by-week
Week 1: Active burping
- Place dried buds loosely in mason jars (fill 75% — leave airspace for gas exchange)
- Open (burp) each jar 2–3 times daily for 10–15 minutes
- If the inside of the jar smells like ammonia or the buds feel moist, they're too wet — take buds out and dry for 2–4 hours, then re-jar
- Humidity inside the jar should stabilize at 58–65% RH (use a small hygrometer in the jar)
- If humidity reads above 70%: buds are too wet. Remove and dry further. If below 55%: buds are too dry. Add a humidity pack (Boveda 62%) or a small piece of fresh fan leaf for 24 hours to rehydrate slightly
Week 2: Reduced burping
- Burp once daily for 5–10 minutes
- The hay smell should be fading
- The strain's natural terpene aroma begins emerging
- Humidity should be stable at 58–62% RH
Weeks 3–4: Maintenance
- Burp every 2–3 days for 5 minutes
- The aroma should be developing fully
- Smoke quality improves noticeably between weeks 2 and 4
- Some growers consider the cure "done" at 4 weeks
Weeks 4–8+: Extended cure (optional)
- Burp once per week (or seal with a Boveda pack and don't open)
- Flavor and smoothness continue improving through week 8
- Diminishing returns after 8 weeks for most strains
- Some strains (heavy indicas, high-terpene varieties) benefit from 3–6 month cures
Optimal conditions
| Parameter | Target | Why |
|---|---|---|
| Temperature | 60–68°F | Preserves terpenes, prevents mold |
| Humidity (in jar) | 58–62% RH | Maintains enzymatic activity without mold risk |
| Light | Complete darkness | Light degrades THC and terpenes |
| Container | Glass mason jars | Inert, airtight, doesn't impart flavors |
Humidity control
Boveda or Integra Boost packs (62% RH) are the simplest way to maintain perfect humidity:
- Place one pack per quart jar (or one per ounce of flower)
- The pack absorbs or releases moisture to maintain 62% RH
- Eliminates the need for careful burping after week 2
- Replace when the pack becomes rigid (no longer pliable)
The debate: some growers believe humidity packs strip terpenes. The research is mixed — Boveda claims their packs don't absorb terpenes, and most side-by-side tests show negligible difference. The convenience benefit outweighs any theoretical terpene risk.
Curing containers
Glass mason jars (recommended)
- Inert (doesn't react with terpenes or cannabinoids)
- Airtight seal
- Transparent (store in dark location or use dark jars)
- Available in quart (1 oz capacity) and half-gallon (2 oz)
- Affordable and reusable indefinitely
Stainless steel containers
- Inert and lightproof
- More expensive
- Work well but no advantage over glass in a dark location
Plastic containers
Not recommended. Plastic can:
- Absorb terpenes (reducing aroma)
- Outgas plasticizers that impart off-flavors
- Build static charge that strips trichomes from buds
- Not seal as tightly as glass
Vacuum-sealed bags
Useful for long-term storage (3+ months) after initial jar curing is complete. Not suitable for active curing — the vacuum crushes buds and doesn't allow burping.
Turkey bags / oven bags
Used by commercial operations for large quantities. The nylon is relatively inert and doesn't strip terpenes significantly. Acceptable for bulk curing but harder to control humidity than jars.
Troubleshooting
Ammonia smell in the jar
Cause: buds are too wet. Anaerobic bacteria are decomposing plant material. This is the beginning of mold.
Fix: immediately remove buds from jars. Spread on a drying rack in a well-ventilated space for 12–24 hours. Re-jar when buds feel dry on the outside. Resume burping 3x daily.
Hay smell won't go away
Cause: either the buds were dried too fast (high temperature, low humidity drying) or they're too dry for enzymatic chlorophyll breakdown.
Fix: if buds are below 55% RH in the jar, add a 62% Boveda pack to slowly rehydrate them. Some chlorophyll breakdown may resume. If the buds were dried at high temperature (above 75°F), the enzymes may be denatured and the hay taste is permanent — a drying error, not a curing one.
Buds are too dry (crispy)
Cause: over-dried before jarring, or too much burping.
Fix: add a 62% Boveda pack and seal the jar for 48 hours without opening. The pack will slowly rehydrate the buds. Don't add wet material (orange peels, lettuce, wet paper towel) — these introduce mold risk and inconsistent moisture.
Mold in the jar
Cause: buds were too wet when jarred (above 65% RH), inadequate burping, or ambient contamination.
Fix: if caught early (small white fuzzy spots on one bud), remove the affected bud and all buds touching it. Dry the remaining buds for 6–12 hours and re-jar. If extensive (entire jar has visible mold), discard the contents. Do NOT smoke moldy cannabis.
Prevention: always dry to the point where small stems snap before jarring. Use a hygrometer in the jar. Never jar above 65% RH.
How long to cure
| Duration | Quality level | Notes |
|---|---|---|
| 0 weeks (uncured) | Harsh, hay smell, burns unevenly | Smokeable but unpleasant |
| 2 weeks | Noticeable improvement, reduced hay | Minimum acceptable cure |
| 4 weeks | Good — smooth smoke, emerging terpenes | Standard recommendation |
| 8 weeks | Excellent — full terpene expression, very smooth | Optimal for most strains |
| 3–6 months | Premium — complex, refined, wine-like aging | Diminishing returns but some strains benefit |
| 6+ months | Risk of terpene degradation | Only for long-term storage with Boveda packs in dark, cool conditions |
The minimum viable cure is 2 weeks. Below that, the chlorophyll is still dominant and the smoke is harsh. Most noticeable improvement happens between weeks 2 and 4.
Common mistakes
- Jarring too wet — the #1 curing mistake. If stems bend instead of snapping, the buds aren't dry enough to jar. Wet buds in sealed jars grow mold. Dry properly before jarring
- Drying too fast — rapid drying at high temperature denatures the enzymes that break down chlorophyll. The result is permanently harsh, hay-tasting flower that no amount of curing will fix. Dry slowly at 60°F / 60% RH
- Not burping — the jar builds up moisture and gases from biological activity. Without regular air exchange, humidity spikes above 70% and mold develops. Burp daily for the first week, then gradually reduce
- Storing in light — UV and visible light degrade THC (converting it to CBN) and break down terpenes. Store jars in a dark cabinet, closet, or box. If using clear jars, keep them in a dark location
- Skipping the cure entirely — "it's dry, let's smoke it" wastes weeks of growing effort. A 2-week cure dramatically improves the product you spent 4 months growing. The patience pays off in every bowl
For the drying process, see our drying guide. For harvest preparation, see our harvest guide.