I don't know myself. The phals just seem to spike when they feel like it in the late fall or winter, once in a while in the summer if they are outside and the nighttime temps are low enough. I have an Encyclia cochleata that was part of the group of orchids that were given to me. A few weeks ago I noticed what I thought were new leaves coming out of the center of the mature growths. I just found out that they are sheaths, but it may not bloom until spring. Still, I am thrilled!