Don't know your set-up, so this may not help much...

Can you place the taller plants to the right, and keep the light to the left, and tilted? Would end-up side-lighting the taller ones, but it may buy you enough room to finish without topping 'em, and side lighting still keeps 'em going. (albeit a tad crooked)

I wouldn't keep topping them as needed. The stress could force 'em into hermaphrodism or death. No chance of bending and tying the tops down a bit? At 4 weeks into flower, might be a tad tricky, and the top may snap off. If it does, keeping it as a clone is an option, but it will take longer to revert back to veg cycle and to take root.

Cutting a hole in the ceiling for more headroom isn't an option, huh...?
Rusty Trichome Reviewed by Rusty Trichome on . plants too tall!!!! Blessings All, My lovely ladies are getting too tall for my ceiling!!! They are 4 weeks into a 12 week flowering cycle and I have already raised the lights as high as they go. I gave them bushmaster last week and it slowed the growth but I don't think it has stopped it. What do I do know? Do I absolutely have to top them? How much should I cut off? Just until they are no longer in heat or do I have to cut more to allow them to grow? Should I just determine the maximum height and keep Rating: 5