I know this is an old thread, but I would like to offer my 2 cents, probably really only worth minus 2 cents. As said by many, a clone is always the age of the parent, so I agree with looking at the little calyx. People say "But I have a limited grow space, I have to keep them small" True, true. USE LED or CFL. Personally, use a 5 Tube 3 foot 325W Panel CFL. You can all put set this so low, the plant has no work to get the light it wants and burn is almost non existent with these lights, be it LED or CFL. I go by a basic formula and one can accept it or deny it. From seed, the plant really needs to follow the natural genetics (Auto-Flower N/A) 45 Days. Again, using NON MH/HPS, burn is just not an issue. As you all know, the less the plant needs to get to light, the smaller and bushy it stays. Also as you know, once turned to Flower, most genetics will end up 18-24 inches higher in that time in Growth. Again, closer light, less stretch. Some will, especially with space issues, keep the LED or CFL (If not using those the whole way) use either. If you want more larger bud, you turn to HPS. I do not even use, wait I do not grow, HPS until the last 3 weeks in the flower mode. I do not take away CFL/LED even then, but place the HPS at least 2-3 feet above the top. Just my minus 2 cents.