noissee
Mame
First of all, I agree with Tom about the lava rock. I use mostly lava with a little bit of pine bark for all my ficus. It really keeps the humidity level up in the pot. If you will be leaving this in the greenhouse all year round, then your options are greatly increased than if you were planning on bringing it out in the summer. Ficus love humidity; and if they have a warm, humid environment, then you can do just about anything to them. As for the apex... Are you asking should you graft on a branch for the apex? Or are you asking about bending the trunk upright to make it centered? Well, since this is a ficus; and since this is in the greenhouse; I would just make a wedge-shaped notch in the trunk and bend it over. They seem to recover very well from this, and you can put bends into really thick trunks this way. If you want to read about trunk notching just google "trunk notching bonsai."