Generally pbulbs should live several years, I believe - but sometimes things happen - at least I have had pbulbs die and don't always know why. I leave them til they are good and dead, so long as the rest of the plant looks OK - tho I don't know that it is recommended or not. I actually have one plant with a couple dead, dried pbulbs that have been there quite some time. Plant has been growing well otherwise. I will remove them when I repot.