Late flower mold window: the numbers that matter

We are entering the danger zone out here in the PNW and I want to share what has saved my runs the last few years. Once you hit weeks 5 and 6 of flower, your buds are dense enough that internal moisture gets trapped, and botrytis moves fast. The environmental targets I hold are below 50% RH during the day and below 55% at night. If you cannot hit those, you are gambling. Temperature swing is the one people underestimate. When nights drop and you still have warm days, that swing causes condensation inside the canopy. I try to keep the day-to-night difference under 10 degrees Fahrenheit. That is harder outdoors obviously, but even partial control helps. Airflow is the other piece. Defoliation in late flower is controversial but i pull any large fan leaves that are trapping moisture against bud sites. Not a full strip, just opening the canopy so air moves through. Static, humid air is where bud rot starts every single time. I also start checking the forecast 10 days out once i'm in late flower. Any multi-day rain event coming and I seriously consider pulling early. A week of grey wet skies will do more damage than losing a few percent potency to an early harvest. Anyways, these are the numbers I work with. Dial in your environment now, not after you see the first grey patch.

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