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. 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.
What's happening
At harvest, flower is ~75–80 % water (typical fresh-to-dry weight ratio ~4:1 to 5:1)being reviewed. 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 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 weightbeing reviewed [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)being reviewed. 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 (long-term storage) |
| 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/wbeing reviewed | [7] |
| Finished weight | ~20–25 % of wet weightbeing reviewed | Grower practice |
How to do it
- Before the chop, clean the dry space, set the climate and check the hygrometer (salt test).
- 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.
- Hang with space between branches; buds shouldn't touch.
- Log RH/temperature; aim for slow, steady weight loss.
- From day 5, test small stems: bend → wait; snap → nearly ready.
- 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: 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 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 contentbeing reviewed.
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.
