Plants reflect green, thus their green appearance... so "who the hell knows" I do, they reflect it thus doing nothing for them.
There are some that believe that a little green is beneficial, it has to do with secondary pigmentation regarding 530nm or something along those lines. Personaly I don't belong to that camp, and use a 530nm Green Inova X1 as a night light if I must go in the growroom in the night cycle.
The reason I 'm skeptical is that I've never prolonged a plants cycle by interfering with the plant transisioning from veg to flowering from using a 530nm green nightlight. I could be wrong, but this is why some LED growlights add a one or two green leds in their fixture.
I didn't read all the replies in this thread, but saw the Prostar emitters being discussed. Let me be the first to mention, the Prostar red and blue emitters are NOWHERE in the same league as CREE XLAMP emitters. I have plenty of Prostar emitters that I've tested and they are not as good as what the spec sheets state in my observations and testing. I've tested almost every emitter on the market and thus far the CREE offerings are the best on the market, thats why Procyon and others use CREE Xlamp emitters, even thought the Prostars cost less per emitter.
Here's my 530nm night light if I have an emergency and must enter the growroom while the plants are sleeping.
It's bright enough, not nearly as bright as the Q5 emitter it's light is shining on though, then again, the Q5 bin isn't a grow light blue or red emitter. The Q5 is great for flashlights, but not so much as a grow light emitter, but it could be used since if memory serves, its 6200k
PS, You can buy a Inova green X1 530nm for $7.99 at Beachaudio.com