you only need a 10˚F drop at night. It is not necessary to go into the low 60's. It will stunt growth to go much below 60˚F. Generally if you have a healthy Phal, it is usually lack of light that will stop a phal from spiking. Some phals prefer to spike in the spring, some in the winter, some all year. A healthy phal with good culture should remain in bloom for most of the year. I have spikes that are over a year old that continue to bloom. I suggest that you don't cut the spike, a healthy plant is very able to support new growth and flowers.