Blue Dream is one of my favorite weeds ever! When leaves on the bottom die too soon might also be that theyre taking nutes from them because they cant find them in the soil. Im guessing they all eat the same, that one might need a bit more. Just my thoughts, if someone disagrees youd be better off listening to them probably. It could just be normal for that plant, I noticed that my blueberry tends to get rid of the first leaves quicker than other autos I planted before. I also has a shorter lifespan.