So why do some people use green porch lights? This one doesn’t have to do with Halloween or Christmas, but it is related to another holiday. What does a green porch light mean?

SAIKI, Oita prefecture--A “light farming” technique that stimulates ... Researchers found that raising flounder for 12 hours a day under green LED lights significantly speeds up growth ...

The position of the lights varies between models, however, each light is labeled according to its meaning. Note that if you're using a Raspberry Pi Zero, there's only a single green LED — you ...