Auto Grand Daddy Purple

This will be our outdoor strain for this year, a very long grow... we start seedlings under 16.5 hours and will take outside near ro the solstice when we receive about 15.5 hours... we do this to prevent re-vegging but its not a perfect science and we usually get 1 that will go into an early flower regardless.. in sure there's a better way to do this but I'm yet to discover one...suggestions are definitely welcome :)