[stonedragonfarms]

A. Which cymbidiums are you growing?
B. What is your average night time temperature?
C. What is your average day time temperature?

Around here, this sort of thing happens if spikes are initiated and then left to grow on where night time temps are too warm; you will see the spike rapidly elongate, but when the buds clear the sheath they will rapidly begin to yellow and fall off. The few "warmth tolerant" cymbidiums in my collection are less prone to doing this, though they still show better colors when grown under cooler conditions (in my experience). Hope this helps a bit,
Adam