# Drying cannabis: the 60/60 method and water activity

> Dry slowly and in the dark at about 15–21 °C (60–70 °F) and 55–62 % RH, the popular 60/60 target, for 7–14 days until small stems snap and buds reach a water activity of about 0.60–0.65. ASTM D8197 sets 0.55–0.65 aw as the range that protects against mould without making flower brittle. Judge the bud (stem snap, an equilibrated jar reading, weight), not the room. Wet vs dry trim is grower preference. Fast, warm drying loses volatile monoterpenes, and wet, still air grows mould.

- Canonical: https://genetixbay.com/knowledge/harvest-cure/drying.html
- Category: Harvest and cure · Level: Beginner
- Evidence: Supported · Status: Draft: awaiting expert review (some figures are being checked)
- Stage: Harvest · Systems: Any system
- Updated: 2026-10-31 · Licence: CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0/), attribute "GenetixBay Knowledge Base (genetixbay.com/knowledge)"

## Questions and answers

**Is freeze drying better for cannabis?** Freeze drying is not proven better for cannabis. GenetixBay rates it contested and does not recommend it, and a slow hang dry followed by a proper jar cure remains the standard. The main goal of any drying method is keeping volatile monoterpenes, which research shows shift and escape during air-drying, so a slow, cool, dark dry matters more than the equipment.

**Why does my weed smell like hay?** Weed smells like hay when it was dried too fast, over-dried or affected by bacteria. A 3-day hot dry crisps the outside while volatile [terpenes](https://genetixbay.com/knowledge/glossary/terpene.md) evaporate with the water, and over-drying below [water activity](https://genetixbay.com/knowledge/glossary/water-activity.md) 0.55 strips aroma further. The smell never truly comes out and curing won't fix it, so dry slowly at 15–21 °C and 55–62% [RH](https://genetixbay.com/knowledge/glossary/relative-humidity.md).

**What is the 60/60 drying method?** The 60/60 drying method means hanging cannabis in the dark at about 60 °F (15–16 °C) and about 60% relative humidity, with gentle air movement that doesn't hit the buds, for roughly 7–14 days. It is grower practice rather than a researched optimum, but slow, cool drying helps keep volatile monoterpenes. One grower survey averaged about 65 °F and 53% RH.

**How long should cannabis dry?** Cannabis should dry for about 7–14 days, according to grower practice. Start testing small stems from day 5: a bend means wait, a clean snap means nearly ready. The dry is finished when a sample sealed in a jar for 12–24 hours reads a stable 58–65% RH and the flower weighs about 20–25% of its wet weight.

**What humidity and temperature for drying?** Dry cannabis at 15–21 °C (60–70 °F) and 55–62% relative humidity, in the dark, with gentle room circulation and air exchange to remove moisture but no [fans](https://genetixbay.com/knowledge/glossary/fan-leaf.md) blowing on the buds. Too warm or too fast loses terpenes, while too slow, too warm or still, wet air invites [Botrytis](https://genetixbay.com/knowledge/glossary/botrytis.md) and other moulds. Never dry in the grow tent with lights or heat running.

**What water activity should dried cannabis have?** Dried cannabis should reach a water activity of about 0.60–0.65 before curing and settle within 0.55–0.65 overall, the range in the ASTM D8197 standard. Below 0.65 guards against mould, above 0.55 avoids brittle, crumbling flower, and above 0.68 means more drying is needed. Measure with a sealed sample: once equilibrated, the jar's RH divided by 100 equals water activity.

**Should I wet trim or dry trim?** Wet or dry trimming is grower preference, and both make excellent flower. Wet trim dries buds faster, saves hanging space and suits humid rooms with high mould risk. Dry trim slows the dry because sugar leaves act as a jacket, suits dry rooms where buds would crisp, and is far easier on the hands at volume. Pick the method that suits your room and workload.

**Is dry trimming better than wet trimming?** Dry trimming is not proven better than wet trimming; no independent peer-reviewed study compares their terpene or [trichome](https://genetixbay.com/knowledge/glossary/trichome.md) retention, so GenetixBay treats it as an open trial. The founder prefers dry trim after hand-trimming hundreds of pounds, because brushing a dry bud is easier than scissoring a wet, sticky one, and he accepts slight trichome loss since the trim goes to hash or edibles.

**How much weight does cannabis lose when drying?** Cannabis loses roughly three-quarters of its wet weight when drying, finishing at about 20–25% of its harvest weight, because fresh flower is about 75–80% water; the exact figure varies with cultivar, bud density and how much stem is weighed. Tag and weigh one branch at the chop and every day or two afterwards: a slow, even fall in weight marks a good dry.

**My buds dried in 3 days, are they ruined?** Buds dried in 3 days usually lose quality rather than being lost outright: expect harsher smoke, fewer volatile terpenes and a hay or grassy smell. A fast dry crisps the outside while the inside can stay wet, so seal a sample jar for 12–24 hours and check it stays below about 65% RH. A cure will never fully fix a bad dry, so slow the next one down.

**Short answer.** Hang whole plants or branches in the **dark** at about **15–21 °C (60–70 °F)** and **55–62 % RH** ("60/60": ~60 °F, ~60 % RH), with gentle air movement that doesn't hit the buds, for **7–14 days**. Done when small stems **snap** rather than bend and buds read **~0.60–0.65 water activity (aw)**. ASTM D8197 specifies **0.55–0.65 aw**: below 0.65 to guard against mould, above 0.55 to avoid brittle, crumbling flower [1][2]. Slow drying is about **keeping volatile monoterpenes**; air-drying measurably shifts oil composition away from monoterpenes [3].


> **Greenleaf's standing challenge: [darkness before harvest](https://genetixbay.com/knowledge/glossary/darkness-before-harvest.md).** 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](https://genetixbay.com/knowledge/glossary/photosynthesis.md) 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.

## What's happening

At harvest, flower is ~75–80 % water (typical fresh-to-dry weight ratio ~4:1 to 5:1). Water leaves the surface first; the inside dries by diffusion through the stem and bud. Dry too fast and the outside crisps while the inside stays wet, and volatile terpenes evaporate with the water. Dry too slowly, too warm, or in still, wet air, and *Botrytis* and other moulds grow [6].

**Water activity (aw)** is the energy status of water in the bud (0–1.0): the [equilibrium RH](https://genetixbay.com/knowledge/glossary/equilibrium-relative-humidity.md) of the air around a sealed sample, divided by 100. It is what microbes "feel", unlike **moisture content** (% water by weight). A bud in a sealed jar **at equilibrium** at 62 % RH has aw ≈ 0.62; the room's RH, or a jar you just opened, tells you nothing about the bud. At aw 0.55–0.65, dried flower holds roughly 8–12 % water by weight [7].

**How to tell the bud is done:** small stems **snap**; a sample **sealed 12–24 h** reads a stable 58–65 %; and the flower has lost roughly three-quarters of its wet weight, ending at about **20–25 % of wet weight** (depends on cultivar, density and stem). Weigh a tagged branch at the chop and every day or two: a slow, even fall is a good dry.

## Numbers that matter

| Parameter | Target | Evidence |
|---|---|---|
| Temperature | 15–21 °C (60–70 °F) | Grower practice; grower survey average ~65 °F [4] |
| RH | 55–62 % | Grower practice; survey average ~53 % [4] |
| Duration | 7–14 days | Grower practice |
| Light | Dark | Light degrades [THC](https://genetixbay.com/knowledge/glossary/thc.md) ([long-term storage](https://genetixbay.com/knowledge/harvest-cure/long-term-storage.md)) |
| Air | Gentle circulation in the room, not on the buds; exchange to remove moisture | |
| End-point aw | ~0.60–0.65 to start cure; final 0.55–0.65 | Established standard [1] |
| "Needs more drying" | aw > 0.68 | [2] |
| Hygrometer in jar test | Stable 58–65 % RH after 12–24 h sealed (aw ≈ RH / 100 once equilibrated) | Grower practice |
| Moisture content at end-point | ~8–12 % w/w | [7] |
| Finished weight | ~20–25 % of wet weight | Grower practice |

## How to do it

1. Before the chop, clean the dry space, set the climate and check the hygrometer (salt test).
2. Cut whole plants or large branches and remove big fan leaves. Then **trim wet now or dry later**: it's grower preference (see below). Weigh and tag one branch so you can track weight loss.
3. Hang with space between branches; buds shouldn't touch.
4. Log RH/temperature; aim for slow, steady weight loss.
5. From day 5, test small stems: bend → wait; snap → nearly ready.
6. Buck, trim if you haven't, and jar to measure: seal a sample with a hygrometer or aw meter and leave it untouched; if it reads above ~65 % after 12–24 h, keep drying.

## Wet trim vs dry trim

> **House position: grower preference.** Both work, and both make excellent flower. The founder has trimmed hundreds of pounds by hand and prefers to **dry trim**: brushing the sugar leaf off a dry bud is far easier on the hands than scissoring a wet, sticky one, even at the cost of a little trichome loss, and that loss doesn't matter much because it all gets used anyway (the trim and the shake go to hash or edibles). Plenty of skilled growers wet trim for good reasons. Pick the one that suits your room, your hands and your volume.

| | Wet trim | Dry trim |
|---|---|---|
| Speed of drying | Faster (less leaf to buffer); good in a humid room where mould risk is high | Slower (sugar leaves act as a jacket); good in a dry room where buds would otherwise crisp |
| Space | Trimmed buds take less hanging or rack space | Whole branches need more hanging space |
| Hands and labour | Sticky resin gums scissors; slower, harder on the hands | Leaves are crisp and brush or snip off easily; far easier on the hands at volume |
| Trichomes | Fewer heads knocked off while handling the wet, pliable bud | A little more trichome loss from handling dry flower; it ends up in the trim, which still gets used |
| Look | Tight, precise manicure | Slightly looser look; handle gently |
| Who prefers it | Humid climates, rack dryers, growers who want the finish done on day one | The founder; terpene-focused growers who want a slower dry; anyone trimming a lot by hand |

## Other drying methods

- **Freeze drying and [water curing](https://genetixbay.com/knowledge/glossary/water-curing.md):** *Contested*. Neither is proven to give better flower, and GenetixBay doesn't recommend either. A slow hang dry and a proper cure remain the standard.

## How to confirm it worked

Buds feel dry outside but slightly springy; small stems snap; aroma is intact (not "hay" or "grass"); [jarred](https://genetixbay.com/knowledge/glossary/curing-jar.md) aw settles at 0.58–0.65.

## Common mistakes

- Drying in the grow tent with lights or heat running.
- Fans blowing directly on buds.
- 3-day "fast dries" in summer heat. Expect harsh smoke and a hay or grassy smell; **a cure will never fix a bad dry** (house position). Hay smell means bacteria, over-drying or drying too fast, and it never truly comes out.
- Over-drying below aw 0.55 (brittle, terpenes lost, hay smell).
- Ignoring mould: break open the largest colas; grey fuzz or brown inner tissue = discard that bud.

## Safety

Mouldy cannabis can carry *Aspergillus* and other fungi that are a health risk, particularly for people with weakened immune systems. When in doubt, throw it out.

## Evidence

Wet vs dry trim is grower preference (house position): we found no independent peer-reviewed comparison of terpene or trichome retention, which makes it an open GenetixBay trial. The rejection of freeze drying and water curing is a house position (*Contested*). One 2023 study compared freeze-drying with other drying methods for terpene content.


The aw range is *Established* as an industry standard [1][2]. Terpene loss on air-drying is *Supported* [3][5]. The 60/60 recipe and 7–14 days are *Grower practice*; there's no published study that optimises cannabis drying rate for terpenes.

## Sources

1. ASTM D8197. Standard Specification for Maintaining Acceptable Water Activity (aw) Range (0.55 to 0.65) for Dry Cannabis Flower. ASTM International. https://store.astm.org/d8197-22.html
2. ASTM International, Standardization News. Two cannabis standards you should know about (D8196 water activity measurement; D8197 range). https://sn.astm.org/node/2445/printable/print
3. Ross SA, ElSohly MA, 1996. The volatile oil composition of fresh and air-dried buds of Cannabis sativa. Journal of Natural Products 59(1):49–51. https://diverdi.colostate.edu/C442/references/analysis/GC/j_nat_prod_1996_v59_p49.pdf
4. Cannabis Business Times. Special report: cannabis post-harvest benchmarks (grower survey; average drying ~53 % RH, ~65 °F). https://www.cannabisbusinesstimes.com/business-issues-benchmarks/cannabis-post-harvest-operations/article/15689633/post-harvest-benchmarks-with-room-to-experiment
5. University of Georgia (thesis). Effects of drying method and storage on cannabinoids and terpenes in hemp. https://openscholar.uga.edu/record/27813
6. Punja ZK, 2021. Emerging diseases of Cannabis sativa and sustainable management. Pest Management Science 77:3857–3870. https://pmc.ncbi.nlm.nih.gov/articles/PMC8451794/
7. Modern Canna Laboratories. 2025. Validation of moisture content and water activity methods in cannabis flower (method-validation white paper; cured flower typically 5-9 % moisture by water-specific methods at aw 0.45-0.60; 103 °C oven loss-on-drying overstates moisture). https://moderncanna.com/wp-content/uploads/2026/04/Method_Validation_Study_Moisture_Content_and_Water-Activity_in_Cannabis_Flower.pdf