well, first, when you water, saturate the soil and let it dry; wet spotting is very bad, and is essentially the same as underwatering. 90% of your roots will wrap around the inside of the pot, so watering the center is a bad idea.
as for heat, exhaust is important. take the heat out of the grow area by using a fan to pull it out. leave a hole somewhere and you'll create a passive intake, and you should see a differece right away.
btw, what are the temps, are you using fans, what kind, how big is the grow box... and anything else that may be helpful in helping you...
love, kp