its very simple... all normal light (ie sunlight) has all the colors of the spectrum in it.. when your eyes see an object that is a certain color, the object that you are seeing is absorbing all the light EXCEPT the color that you see... that color of light is being reflected back to your eyes
(example: white and black are technically not colors.. when you wear white on a hot day, your white clothes reflect ALL colors of light, keeping you cooler.... black on the other hand, is the presence of ALL colors, so your black clothes absorb all colors of light, making you sweat your ass off even more than if you were wearing white )

since plants are green to your eyes, they don't process green light at all, but reflect it so that you can see them. the rest of the colors are used by the plant, but mainly blue and red. so you can use a green light for maintenance during the dark cycle, because the plant can't 'see' green light and will think that it is still dark.... but there is still a possibility of light leaks as you enter/ exit etc if you are not very careful

i prefer to just set my lights to be on when i know i can be home to do the maintenance and not mess with all that, but im paranoid