Hi Thea, I agree with Ken, you can check the root ball. The only time before I saw my Plumie getting that dried out stem, when there were no roots formed, and the leaves were not formed either but it did manage to bloom.
But your plant has good formed leaves, so it is also possible it is very thirsty. Being thirsty, the plant is conserving available moisture so it is dropping the older, lower leaves early. Maybe up to this last week of October, you can still water it thoroughly till you see water gushing out the other end. But don't do it daily, our temps at night are starting to cool down. Eventually you have to scale back watering and just let the plant naturally go dormant. In our area, once we start getting temps below 50F, it is too cold for the Plumies. It is different in SoCal, their low temps are more stable there, but here in NorCal, just have to protect them when temps start going down.
I think we still have this last week of October to safely keep them outside. By November, have to bring them in and let them go dormant. It is a temperature game now, we may still have nice 70's during the day but daytime is much shorter and overnights cooler.
