I was wondering what it is, I know it traps humidity inside but whats it good for when growing MJ? I've heard of putting half of a 2 lt bottle over your plant works as a greenhouse effect. If anyone can help that'd be great! i'll give you some rep too
Isolating warm air inside the structure so that heat is not lost by convection. I can only think of cold weather grow where a greenhouse makes gardening possible. I don;t think they are used to trap moisture.