Couple questions. What was the average humidity during the period that your green leaf was curing in the shed? How closely did you space the leaves between one another?
I agree with Bob and Charly 100%, but I also suspect your average humidity during that period was low. (average humidity over, say, three day chunks) Being the knucklehead that I am, I get a little happy while priming and will occasionally grab a few leaves a little early (Sometimes more than occasionally). I still managed to cure them by keep the leaf alive while curing from green to yellow by opening and closing the shed doors to work with the available humidity available with my climate. Keeping the leaf alive from green to yellow means it needs enough moisture not to dry green but not so high that the leaf rots. It could be dry during the day, and humid at night. I would allow the high nighttime humidity to come in the shed with door open, then close the door in the morning before the air could dry back out, trapping a better humidity on the inside. I have also had to space my leaves very tightly so they would dry more slowly, and therefore die more slowly, allowing them to yellow. I have also had to fight the other direction and turn on fans during rainy periods to keep the air circulating while the humidity was too high. When the humidity was too low for a period, I have had to wet the floor, or suspend towels from buckets so the towels would wick up and add humidity to the air in the shed. The best thing you can have during curing is a thermometer, hygrometer, and watch the weather reports.
Heres a photo of my strung leaf during a period of low humidity when I was fighting to keep the leaf from drying green. Note how closely packed the leaf is during this period. If I had been getting periods of rain, the leaf would have been spaced further apart, but we were in a severe drought at the time.
Got a good soaking rain right now in guntersville. knuck.hope your getting some of it. Is all this rain this late in your grow good or bad?
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