there a few things that you can do to control that beautiful beast of yours... it seems like its going to be hard considering how tall they gotten, but you might be able to pull through. You can go ahead and use LOC NAR's advice and tie it down, you can also set a net at the top of it and anchor it enough so that it applies SOME pressure to the plants... you can also try using like a clear platic tray with some ventilation wholes to allow humidity to escape and then tie some type of anchors to it (fishing weights, etc), just make sure not to apply to much pressure and hurt/snap your baby.

Good luck bro, Im using the clear plastic tray to keep my cannopy even... just started using it and seems to be doing fine. Good luck bro :]