For me, if I grow any of my old sativas that I have bred for seeds indoors, plants like my 72 colombian gold or my 74 lambs breath, I have to keep topping the top until they start internoding because if I don't I will run out of room, height wise. But usually when I am growing them indoors, I just top them 2 times and then kick them into flower when they are between 15" to 18" and they still end up being 5 to 5 1/2 foot plants in 4 gallon nursery pots, which really are only 3 gallon pots. Both my colombian gold or my lambs breath can grow up to 5 times whatever size they were when they are flipped. Anyhow... I myself cannot grow them outside because where I live the season is just to short here, they are both 16 to 22 weeks strains, but a buddy of mine who lives in South Texas where I use to live grows them outside all the time and most times they end up being over 25 feet tall even if topped a few times.