This was my takeaway lesson this winter. I had a good lighting setup and a very nice grow tent for ficus, portulacaria etc, but they still didn't have a good winter. Essentially spent winter dropping leaves and regrowing them at the same pace. I think air circulation was the missing ingredient. That, and the fact that it was cool-ish inside the tent.
So I ended up taking mylar and taping it to cardboard or white styrofoam and hanging it creating false walls. It let's air flow in. Wasn't too much money either. It's also not pretty. I used a pallet for a table. Then I put white styrofoam on the pallet to reflect light back up.(I had a sheet of 4x8 sheet)