They will freak out worse with less light than necessary. I have been vegging mine out doors then moving them into tent with a 1000w hps beaming down onto them from 24" away. Havent lost one yet from too much light. If its too close you will notice and can move it up some. Remember lumens= yield. The more light they have the more they produce. I just put some under two 24" T5 flourecents from seed to about 4wks old moved into flower and they are doing great. Hope this helps imp: