Right now my plants are still on 24/0 there almost 2 weeks old now and only 2 of the 4 plants have actually turned out to be healthy. One of them is about 6 inches tall, and the other about 3-4. When should i switch to 18/6?
Actually anything between 24/0 and 18/6 is veg. You can give them 1,2,3,4,5 or 6 hours of dark with the same results. Heck i doubt even 7 or 8 would induce flowering much. But......to answer your question, usually you wait until they are a solid 12" inches or taller to get any amount of bud worth your time. I would say 14 to 16 inches. Personally i wait until 24 but i have room for big plants.