Since im at school, i leave my house at 7:00am and get back at 4:00 pm. thats a total of 9 hours. this is what i use for my DARK PERIOD. This leaves from 4:00-7:00, a total of 15 hours of light. Every1 says that 18 hours of light is needed, and 6 hours of complete dark. Will my plants be "less-good", flower early, or just all around not as good if i keep it this way. these time frames are my only options. i cannot leave the lights on while im at school, long story.