hempie said:
dumb question inc... if they are outside there is no absolute darkness especially during a full moon. so why would a teeny tiny amount of light hurt?
Consider the light source. In your grow room your sun is only a couple inches away from the plant while outside the sun is millions of miles away from your plant. Your sun produces anywhere from 10,000 to 100,000 lumens directly on your plant while the outside sun produces about 10,000 lumens per square foot. A full moon produces roughly .03 lumens per square foot, while any lightbulb or TV that infiltrates your grow room may produce a couple hundred lumens per square feet. This is a HUGE percentage of lumens compared to the little amount of light that is reflected off of a full moon.
To make the math simple, let's say that 100 lumens seep through a crack in your closet door from a light in your room and that you have an amazing HPS setup that produces 100,000 lumens for your plants. 100/100,000 = .001 x 100 = .1%. Compare that to a full moon in an outside grow .03/10,000 = .000003 x 100 = .0003%. You're allowing roughly 1000% more light to reach your plants than what would occur outside...and that's assuming that you have a lighting setup that produces 100,000 lumens. The less lumens you are able to provide, the more devastating the effect of outside light.