Also will add I like to use a Black light in my last weeks of flower,,,You do not grow with a black light ,,,,But that being said ,,there is a benefit it produces UV rays mostly A type ,,this will stress the plants some,,A UV light from a aquarium will work as well I run it 24/7,,it will not bother them at lights out,,I leave it run,,,,I will explain the best I can,,during the last 2-3 weeks of flower a plant is producing resign and tricombs ,,,,What makes you buds smell great and taste great are things called Terpens and Terpiniods ,,the flowering plant produces these on her own,,if the plant is stressed in the last weeks of flower and I said stress not killing or damaging it as you need it to grow not suffer,,,,It produces higher then normal amounts of terpens and terpeniods ,,So I go threw and fleece the plant of most of it's leaves to cause a bit of stress and to make sure all remaining energy goes to buds,,I also use the black light as UV is stressful to a plant and can burn it the same way it can burn you and I,,,,The plants natural defense is to increase resign production to protoect it self from the stressful UV,,,I will add you can use a UVB style of light and are suppose to be effective in growing ,,,I just use my black light for some added stress ,,,and that is how it works to stress them a bit