The real limit is first frost. Any thing green, whether out in the field, or hanging inside an unheated shed, will freeze, and never amount to much. Last year, the evening before first frost, I primed the last of the leaf in the field, then hung it indoors, surrounded by plastic wrap (partly vented) to prevent it from drying too fast. This worked, but was a nuisance to manage.
As for color-curing being easier in cool temps with stalk-cut plants, I don't know the answer. Some varieties seem to cure more rapidly on the stalk, while others take longer on the stalk. Humidity in the shed plays a large role. Stalk-hung leaf seems to tolerate lower humidity without drying green than primed leaf. But even that seems to be variable.
Bob
