Found a surefire way to start Bee-Bee trees, by accident. I received an order of seeds, sowed them in a flat, just covering the seed, watered the flat, and covered it in saran wrap. Placed in a warm location. Monitored moisture level, and waited. And waited, and waited. Nothing. About three to four months later, I forgot about them, one of my pets pulled the saran wrap off and the flat dried out. Death Valley level of drying out. About 5 months later I noticed them again, thought, "Well, they are probably toast, but I have noting to lose, and watered them again. A couple of weeks later, the flat just exploded. I have over 60 trees.
I wonder if the area of Korea they are native to has a dry season, or if maybe they trigger to a drought followed by rain?