Stonerdanswered grow question 4 years ago That is a huge dip in temps during the night cycle and what probably causes your plants' stunted growth!
The difference between light and dark temps should not be over 6-8 degrees Celsius (with 8 being in the extreme).
Try adding a small space heater for your grow space and turned on during the night, preferably placed near the intake vent for better, and more even heat spread!
*28 degrees Celsius/ 82f is perfect temp for non-supplemental (Co2) cannabis grows so you light temps are perfect, it's the night temps that need adjustment.
Hope this helps! Good luck and happy growing :)