Moving plants inside from outside question

I have been forced to move my 4 plants indoors, because of frosty mornings and 4 inches of snow yesterday. They are under the only light I have, and that is a 400 watt metal halide bulb @ approx 14" above the tops of the plants. The crawl space that they are now in is a constant 10 degrees celsius and I am wondering if I need to add HEAT? The plants are now entering their 7th week of flowering. The light itself is not giving off of a lot of heat, and neither is the ballast. Some help with this matter would be greatly appreciated. Thanks pictures to follow, it's dark time now

Yes, add heat, but If your crawl space is uninsulated and vented, then adding heat won't do much. Might make a small difference.

At 10c I would be adding some heat, more so by the roots. MH at this stage of flowering is not great but OK. Switch to HPS if you can and up the Temps for a better return

I moved my last remaining outdoor plant into my garage a couple weeks ago for reasons similar to yours. My garage is heated but I’m cheap and didn’t think I needed to turn the heater on since it was still between 9-12°C in the garage. My plant stalled completely. It’s in week 11 of flower so I wasn’t expecting much growth but the ripening process stopped as well. I turned on the heat to 18°C and the plant has continued to ripen. I wish I would have just given it heat from the beginning, I essentially wasted a whole week hoping it would progress unheated.

Thank you very much for the info, will be adding heat !!