Green orchid root tips turn non-green

[Charles]

This is why I theorize that the plant will grow roots where it "thinks" it needs them. Responding to light, temp and moisture (all either more or less) the plant will shape accordingly. I have orchids that seem to "react" to different needs and stimuli.
I also know that conditions like dormancy and vigorous growth do come and go. Fertilizer can also cause a plant to "stop".