Yeah man you hit the nail on the head bro. The girls have stretched to insane heights. Kinda sucks but it is going to be a good yield by the looks of it already. Anyways I have about 8in to work with. About 5 of the 8 is the HPS. My plan is to move the HPS to the other side while Putting 8 cfls at the top of the big girl. This will give me about 5 more inches I think and I will have 200w on the on big girl. What is your estimate on how much bigger she is going to get?
Well, this is the first grow of blackjack that I've watched, so I'm learning from you. According to this site (
http://en.seedfinder.eu/strain-info/BlackJack/Sativa_Seedbank/), based on two user reports, "
Stretch after the initiation of flowering: ~203 Percent. Initiation of flowering onto around 45 cm (18 in) - Final Height onto around 135 cm (53 in)."
Not sure what kind of wattage they were using. You're only about two weeks into 12/12, so it sounds like you have the more sativa-dom (stretchy) phenos. If I had to guess, I'd say the worst of the stretch is probably over...but it might be wise to have a plan in case they grow more than five inches in the next few weeks. I think ordinarily you shouldn't expect to see any more stretching past the four-week point.
If you have the space, I would favor tying her down a bit. I try to avoid topping during 12/12...but it might be worth an experiment with one of your girls just to see how it works out.
All part of the fun of growing your own! Making those executive decisions...