Factors including long time finishers are:


  1. Heat
  2. How much lighting
  3. How close the lights are
  4. PH going in and out
  5. Feeding schedule (how often give nutes)
  6. Type of CFL lights
  7. How many CFL light (lumen output)
  8. and so on and so forth

You can't just base that a paper says it takes 6-8 weeks and go by that, because like above there are tons of factors that make a plant take longer and depending on how bad the situation it may not even get bigger, it may just mature rather than fill in. Heat will do that especially if not tended to correctly!