Drying and curing decide whether a harvest ends up smooth and fragrant or harsh, hay-scented or mouldy. Most guides to this step repeat grower rules of thumb without saying where the numbers come from. This one takes its targets from a published industry standard, two recent peer-reviewed studies and named professionals, and it marks the places where the evidence runs out. The short version: dry at 60–70 °F with steady airflow, then cure in sealed jars until the air inside holds at 55–65% relative humidity. Everything else on this page explains how to get there and what to do when it goes wrong.
How we sourced this guide: Temperature, humidity and water activity targets come from ASTM International, peer-reviewed journals, Oregon State University Extension and named industry experts, each cited where it is used. Where only grower practice exists, we say so. Checked 26 September 2026.
Table of Contents
Drying and curing cannabis: key facts
- Fresh cannabis and hemp flower is 70–80% water at harvest, according to Oregon State University Extension.
- ASTM standard D8197-22 sets an acceptable water activity range of 0.55–0.65 for dry cannabis flower: below 0.65 to prevent mould, above 0.55 to prevent breakage.
- A 2024 study in Plants describes 15–21 °C (59–70 °F) as the commonly used drying temperature range.
- Freshly harvested cannabis lost 25–77% of its weight while drying, mostly in the first one to three days (Forensic Chemistry, 2017).
- In a 2025 study, curing hemp for three weeks in glass jars or Mylar bags did not significantly change total cannabinoid content.
- About 80% of 240 traditionally dried inflorescences in the 2024 study were highly infested with the mould Alternaria alternata by day 12.
What is drying and curing cannabis?
Drying removes most of the water from freshly harvested cannabis over roughly a week. Curing then holds the dried buds in sealed containers so the remaining moisture evens out, bringing the flower into a stable range that resists mould.
The two stages do different jobs. Drying takes flower from 70–80% water down to a point where stems bend and crack but do not snap. Curing is slower and gentler. The buds sit in closed jars or bags, moisture from the centre of each bud moves outward, and the grower lets out humid air until the jar holds steady. Oregon State University Extension describes the full post-harvest sequence as trimming, drying, curing and storing.
| Drying | Curing | |
|---|---|---|
| Where | Open air: hanging branches or mesh racks | Sealed glass jars or bags |
| Temperature | 15–21 °C (59–70 °F) | Room temperature, dark (about 25 °C in the 2025 study) |
| Humidity target | Room air with steady airflow | 55–65% relative humidity inside the jar |
| Typical length | About 1 week; most weight lost in days 1–3 | At least 2–3 weeks |
| Main risk | Mould if drying is slow; hay smell if too cold and still | Mould if jars go in too wet; brittle buds if too dry |
Why dry and cure weed at all?
The best-documented reason to dry and cure cannabis is to stop mould. Flower kept below a water activity of 0.65 resists microbial growth, according to ASTM standard D8197-22. Claims about smoother smoke and better flavour are less tested.
ASTM D8197-22 states that water activity “shall be less than 0.65 to ensure against undesirable growth of microorganisms such as mold, and shall be greater than 0.55 to ensure against physical damage (breakage) in routine handling and storage.” Water activity measures how much water in the flower is free to support mould, on a scale from 0 to 1. In a sealed jar, the air settles at a relative humidity that matches it. Dr. Nadia Sabeh, an agricultural engineer who designs drying rooms, equates a water activity of 0.55–0.65 with an equilibrium relative humidity of 55–65%. That is why a hygrometer inside a closed jar is the home grower’s measuring tool.
Flavour is where the evidence thins. Consultant Kenneth Morrow writes in Cannabis Business Times that flower dried too cold and with too little airflow “retains excessive levels of chlorophyll” and smells like grass or hay. The 2025 Plants study by Chen and colleagues measured a “reduction in the greenness” of hemp after drying and curing. Neither measured taste, and we found no controlled study of smoothness.
How to dry cannabis, step by step
Dry cannabis in five steps: cut and trim, hang branches or rack loose buds, hold the room at 60–70 °F with gentle airflow, check daily, and stop when small stems bend and crack without snapping.
- Cut and decide when to trim. Trim wet, straight after harvest, if you want leaves off before drying. Trim dry if you prefer to hang whole branches. Our weed trimming machine comparison covers both workflows, and our trimming scissors guide covers hand trimming.
- Hang branches or rack loose buds. Whole branches hang from a line or hanger. Loose, wet-trimmed buds dry flat on mesh. Our weed drying rack guide shows how many tiers a harvest needs.
- Hold the room at 60–70 °F with moving air. Morrow advises staying below 75–80 °F and notes many operators prefer 60–70 °F “to preserve the highest percentage of terpenes possible.” Keep a fan moving room air, but not blowing directly on the flower.
- Check every day, especially days 1–3. Most weight leaves in the first one to three days (Warner et al., 2017). That is the time to watch airflow and room humidity most closely.
- Test the stems. Morrow’s test is that the inner stem should “crack, yet bend without being wet,” and a squeezed bud should have give, like a marshmallow. If stems snap or buds crumble, the flower is over-dried.
Drying usually takes about a week. In the 2017 Forensic Chemistry study, weights stabilised after about a week at 22.2 °C and 49% relative humidity. Hot, fast drying is not a shortcut at home. The 2025 study dried hemp with 75 °C hot air in 8 hours and got lower mould counts, but that was a controlled research dryer, not a home setup. Morrow warns that “each and every terpene has a boiling point and temperature at which it begins to evaporate.”
How to cure cannabis in jars, step by step
Cure cannabis in five steps: fill airtight jars loosely, add a hygrometer, open the jars to release humid air while the reading is above 65%, keep them dark at room temperature, and cure for at least two to three weeks.
- Fill jars loosely. Buds should move when the jar is turned. A packed jar traps moisture in the middle. Our curing jars comparison shows how many jars a harvest needs.
- Add a hygrometer. A small digital hygrometer inside the jar reads the equilibrium humidity that matches water activity. The target is 55–65%.
- Burp while the reading is high. Morrow describes checking cure containers “multiple times a day” and exchanging all the air for fresh air until moisture is even. Grower guides such as Leafly suggest opening jars once or twice a day for the first week, then every few days. If a jar reads above 65% within hours of closing, take the buds out and dry them longer.
- Keep jars dark and at room temperature. The 2025 study cured hemp “in dark conditions at ambient temperatures,” about 25 °C and 45% room humidity.
- Cure for at least two to three weeks. The 2025 study used three weeks. Grower guides recommend two to four weeks at minimum and longer for flavour, but we found no controlled test of long cures.
Jars or bags? In the 2025 study, “the influence of curing method was not significant” between sealed glass jars and Mylar bags on moisture and mould, though the authors preferred glass jars in their overall recommendation. Moisture inside the flower rose by 3.3% to 13.6% during curing as it spread from the centre outward. That shift is why a jar that reads within range when you close it can read higher the next day.
Drying and curing timeline, week by week
A typical home dry and cure takes three to four weeks: about one week of drying, then two to three weeks of curing, with the most checking needed in the first three days of each stage.
| When | Stage | What happens | What to do | Source |
|---|---|---|---|---|
| Days 1–3 | Drying | Most weight is lost | Check airflow and room humidity daily | Warner et al., 2017 |
| Days 4–7 | Drying | Weight stabilises by about day 7 | Start stem tests | Warner et al., 2017; Morrow, CBT |
| Day 12, if still wet | Drying | Slow open-air drying reached ~80% heavy mould in one study | Do not let drying drag on in still air | Shimshoni et al., 2024 |
| Week 2 | Curing | Moisture moves from bud centres outward | Burp daily; remove buds if jars read above 65% | Chen et al., 2025; Morrow, CBT |
| Weeks 3–4 | Curing | Jar humidity holds steady at 55–65% | Burp every few days | ASTM D8197-22; Leafly |
| Week 4 onward | Storage | Stable flower | Keep sealed, dark and at room temperature | Chen et al., 2025 |
The timeline assumes a room near the 15–21 °C range. Cooler, damper rooms dry more slowly, and the day-12 row is the reason to fix airflow early rather than wait.
Troubleshooting drying and curing problems
Most drying and curing problems come from moisture moving too slowly or too quickly. Slow drying risks mould and hay smells, over-drying makes buds brittle, and jars filled too early climb above 65% humidity.
Mould
Slow drying in still air is the main mould risk. Shimshoni and colleagues write that “prolonged drying can elevate mold risks due to slow moisture removal.” Keep air moving from day one, keep jar readings below 65%, and throw away any bud with visible mould rather than trying to save it.
Hay or grass smell
Morrow links a grass or hay smell to drying that was too cold with too little airflow, which leaves excess chlorophyll. Next time, keep the room at 60–70 °F with steady air movement.
Over-dried, crumbly buds
Buds below a water activity of 0.55 break easily, according to ASTM D8197-22. Two-way humidity packs, sold to hold a sealed jar near a set humidity such as 58% or 62%, can bring over-dried flower back into range. The set points are the makers’ own. Watch the jar hygrometer rather than trusting the pack alone.
Jar humidity keeps rising
The buds went in too wet. Take them out, spread them on a rack for several hours or a day, and jar them again. The 3.3% to 13.6% moisture rise measured during curing in the 2025 study explains why this happens after a jar seems fine at first.
Does curing make weed stronger?
No evidence shows that curing makes cannabis stronger. In a 2025 study, drying and curing did not significantly change total cannabinoid content, although some acidic cannabinoids converted to their active forms.
Chen and colleagues found that “both drying and curing did not significantly affect the total cannabinoid contents, but resulted in decarboxylation.” Decarboxylation during curing was generally below 2%. The study used industrial hemp, so the results may not carry over exactly to high-THC cultivars. What curing does protect is the flower you already have, by keeping it in the water activity range that resists mould.
Drying and curing cannabis FAQs
How long does it take to dry and cure cannabis?
About three to four weeks in total. Drying takes about a week, with weights stabilising by day 7 in one study, and curing takes at least two to three weeks. The 2025 hemp study cured for three weeks.
What humidity should curing jars be at?
Between 55% and 65% relative humidity inside the sealed jar. That matches the 0.55–0.65 water activity range in ASTM D8197-22, which guards against mould above 0.65 and brittleness below 0.55.
How often should you burp curing jars?
Often while the hygrometer reads above 65%. Consultant Kenneth Morrow checks containers multiple times a day until moisture evens out, and Leafly suggests once or twice a day for the first week, then every few days.
Can you cure weed in bags instead of jars?
Yes. A 2025 study found no significant difference between sealed glass jars and Mylar bags in final moisture or mould levels during a three-week cure. The authors still preferred glass jars in their overall recommendation.
How do you know when weed is dry enough to cure?
The inner stem should crack but still bend without being wet, and a squeezed bud should have some give, according to consultant Kenneth Morrow. Stems that snap cleanly mean the flower is over-dried.
Start your next dry and cure
Set up the drying space before you cut. That means a spot at 60–70 °F, a fan that moves room air, and either a line for branches or a mesh rack sized to your harvest from our drying rack guide. Buy jars and a small hygrometer at the same time, so you can move buds into the cure as soon as stems bend and crack. For the grow itself, see our indoor marijuana grow setup guide. Home cultivation is legal only in some states, so check your state’s rules first.
Sources: ASTM D8197-22, “Standard Specification for Maintaining Acceptable Water Activity (aw) Range (0.55 to 0.65) for Dry Cannabis Flower”; Chen et al., “Postharvest Drying and Curing Affect Cannabinoid Contents and Microbial Levels in Industrial Hemp,” Plants 14(3):414 (2025); Shimshoni et al., “In Pursuit of Optimal Quality: Cultivar-Specific Drying Approaches for Medicinal Cannabis,” Plants 13(7):1049 (2024); Warner et al., Forensic Chemistry 3 (2017): 52–57; Oregon State University Extension, “Post-harvest processing of hemp flowers” (2022); Kenneth Morrow, “Master the Art of Drying and Curing Cannabis,” Cannabis Business Times; Dr. Nadia Sabeh, “Drying Cannabis: Is There a Science Behind the Art?” (2021); Leafly, “Drying and Curing Bud” (updated May 2025). All checked 26 September 2026.
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