Charlie got it exactly right. Short, bushy indicas seem to re-grow best. Here is the best part about doing a re-grow-
You will usually get 150-200% yield off the re-grown plant as you did the same plant the first time! Plus, if a strain
took 6 weeks to finish flowering it would only need 4-5 weeks flowering to finish as a re-grow. So, harvest like Charlie
says then kick your lights back to 18/6 or 20/4 and give her 4 weeks to re-veg. After 4 weeks go back to 12/12 and
wait for an early and large harvest. NOTE -- It works out perfect if you have another grow ready to go when you harvest.
Good Luck, BigSteve.