The closer to the light the more lumens they get. (Be careful don't burn them). You can get them within few inches with flouros and about 10-12" away with up to 400w HID. The light is most intense directly under the light so put smaller plant there and bigger ones around. Called the 'stadium' arrangement cause with enough plants can look like a bowl. If you are growing indoors, you will seriously want to consider starting 12/12 with the larger one (If you have more than one light) then you can continue vegging the others until they catch up. This will cause different harvest times, but not by much and you can't smoke it all at once anyway.