How dark is dark? lol

some growers claim a desk lamp 20 feet away will interrupt the grow cycle, but outdoors the plants do ok with moon and star light, so you're probably ok if you can only see shapes. alternately, hang an extra set of drapes inside the current curtains. look into the blackout curtains night shift workers use, it makes noon into midnight.

Darkest is better..If its in a tent how are you seeing the outline of your plants through the material? Go to wall mart by Black out curtains. They block 99% of light and cost like $19

I believe I read that there should be no more than a foot-candle of light. I'm not sure how to take that measurement exactly, but as Dr mentioned above, the amount of light from the moon and stars doesn't bother them, so neither will a similar amount of light during your dark period.

Oh, and now that I think of it, outdoors the sun creeps up slowly from the East, it doesn't just "turn on" anyways. So I'd say you're good all around.

I go by the simplest rule there is when it comes to dark..step into your grow with lights off, (giving time for eyes to adjust, all though human eyes cannot adjust to total darkness) 2min. later if you can see your hand in front of your face or anything else for that matter its not total dark...

I can always see my hands when I'm outside at night. Just sayin.

I was growing in my spare rooms closet, and there was a window in the spare room. I had some light coming through in the morning during my dark period too, so I covered the window with a heavy blanket and that basically took care of the majority of the light coming through that window. It took care of enough because I was able to grow from seed to harvest without any problems due to light leaks.

either cover it as they said, or make sure it stays consistent. IMO its the changing of the ammount of light during dark cycles that cause problems (hence the moonlight coments). THis is just a theory, no facts backing it. I use tarps to cover the windows, on the outside of the curtains, blocks most of the light between a tarp a curtain and the shades.

I can't believe you can see the outline of your plants from the outside of your tent. What tent do you have?