All of the above mentioned apply as possibilities (although I doubt nitrogen is an issue...developing paph spikes will need it...). However, there is a very sensitive time when a paph initiates a spike...during this time, the bud is clearly visible...either in sheath or just starting to poke out. This stage may even last a few weeks, and it is when a spike is most vulnerable. Anything can be a factor in bud blast at this time...including a variation in moisture level and increases in temperature or decreases in air movement. I lose a lot of paph buds because many are just initiating spikes when they are brought in for the winter...the climate change hits many of them hard, particularly the complex hybrids. I also find that summer time is also rough on the few paphs that spike in the heat...But...once the stalk begins to elongate, the danger zone is passed. While paph buds can blast at any point, 95% blast in the early stages. Take care, Eric Muehlbauer