The problem will not be speed of growth it will be male flowers popin out on the lower branches.But you can just pick em off if you can catch em before they pollinate the rest of the plant(Sometimes the hermie male flowers have no pollin)
You can grow em outside just look for those males everyday until harvest...are you willing to do this?
If not plant a different strain outside and save your OG for a indoor Air conditioned grow.Or get a OG cross...I have OGer's kush x Herijuana!!!I'm about to pop em tomorrow.I'll leasve a link to Motarebel's forum when I get em up there.