Harvest Timing
Outdoor Harvest Timing: Trichomes, Rain and Bud Rot
The trade-off between ripe trichomes and autumn weather, how to catch bud rot early, and when to chop before the rain.
2 min read
Indoors you choose the harvest day. Outdoors the weather has a vote. The buds are fattening up exactly when the nights get cold and wet, and the last two weeks are a balance between letting the trichomes ripen and not losing the crop to mould.
The enemy: bud rot
Bud rot is caused by the fungus Botrytis cinerea. It enters through wounded or dying tissue and thrives in cool temperatures, around 18–24 °C, with high humidity and moisture from rain or dew.[1] Late autumn is exactly that.
It usually starts inside the densest buds, where water stays trapped. By the time you see it from outside, it has often spread inside the cola. And once a bud is infected, it cannot be cured.[1]
How to spot it early
- A single yellow or dried leaf sticking out of an otherwise green bud. Often the first sign.[1]
- Brown, mushy patches inside the bud when you gently part it.
- Grey fuzz: the fungus producing spores. By this stage, act fast.
Check the biggest colas first, every day after rain. Open them gently from the side.
The trade-off: ripeness vs risk
Every extra day outdoors gives the trichomes more time and the fungus more chances. A simple way to decide:
| Trichomes on the calyxes | Forecast: dry week | Forecast: several days of rain |
|---|---|---|
| Mostly clear | Wait | Wait, protect the plant, check daily |
| Half clear, half cloudy | Wait | Consider taking the biggest colas |
| Mostly cloudy | Wait for some amber if you want it | Harvest before the rain |
| Cloudy with some amber | Harvest | Harvest now |
A mostly cloudy plant harvested a few days early is a good harvest. A rotten cola is no harvest at all. Read cloudy vs amber trichomes for what you give up by chopping earlier.
Lower the risk in the last weeks
- Airflow: remove some inner leaves so air moves through the plant.
- Shake off water gently after rain and morning dew.
- Cover against rain if you can: even a simple roof keeps buds much drier.
- Avoid wounding buds: broken stems and crushed calyxes are entry points.
- Harvest in passes: take the biggest, densest top colas first, give lower buds a few more days.
Harvest day
Cut in the late morning, when dew has dried. Don’t harvest wet plants if you can avoid it. If you must, hang them with plenty of space and airflow; a wet harvest is where drying-room mould starts. Our guide on drying and curing covers the next steps.
Tracking the ratio every couple of days makes the call easier when the forecast turns. GrowBotiq Lab counts clear, cloudy and amber from a phone photo, which helps when you need to decide quickly in the garden.
References
- Utah State University Extension. Hemp Bud Rot (Botrytis spp.). Utah Pests fact sheet. extension.usu.edu