Ed Rosenthal has already answered all the questions! If you are new to growing like myself you owe it to yourself to pickup a few of his books! Go to Barnes and Noble or Borders books and you will see how many grow books they carry. A shitload! I have been doing this for under a year and Have learned so much from reading his great books and making mistakes. Book knowledge and hands on experience. This forum is great for discussing techniques, methods and ideas, but not for learning the basics folks. Support the people who have brought years and years of knowledge to us and purchase one of their books, they are doing their part to help everyone become better cultivators!