You can flower out a 3x3 canopy with proper coverage. You can do it in a 4x4 tent, but the light intensity will be lacking on the outer perimeter. Think in terms of canopy size, not number of plants. You could grow one plant scrogged out or 9 smaller plants flipped to 12/12 early. End result will prob be better and more manageable with one plant, but the veg period will be much longer, like 6 to 8 weeks veg.
Good luck! Peace
![Peace :peace: :peace:](/styles/smilies/peace.gif)