i am going to draw on sawleaf for inspiration and patience when answering this question. Vegetative period begins as soon as the plant emerges from the soil, or grow medium. Normal light periods for veg growth is 24 hours a day light, or 18 on 6 off, known as 18/6. I've had no adverse affects from using 24/0, but some people use 18/6 to let their lights and growrooms cool off a bit. You switch to a flowering cycle of 12/12 when your plants are mature enough and have reached a suitable height. For 85 posts you would think you would know this... but oh sawleaf give me the strength......