I know this isnt the season but im planning ahead for my next grow. I want to use a grow tent 4'x4'x7' with a 600w MH light. Only using it to start my seedlings and veg them for a month or so in soil during the winter months so they will be a nice size to put outside all summer. The tent will be in a building that has zero heat and zero insulation. Here is my question and concern: Will the 600w light heat the tent enough so the plants wont die. I live in canada and it gets -20C in winter. I will have a fan in the tent moving air around along with having a couple vents open on the tent to let fresh air in. Need some info since i have never tried this before.