GrowCNanswered grow question 3 years ago Yes, you can use a heat mat. I found them to not have enough power to be useful. I tried two 20 watt pads sitting next to the plants as a heater (not under the pots to warm the soil) and it hardly made a difference in the temperature inside the tent. 40 watts simply wasn't enough to make a difference. I ordered a small 200 watt forced air space heater (added a thermostat to control it) and was enough power to keep the tent warm and needed to run less than 20% of the time to keep the tent warm. A larger tent or colder temps might require a higher wattage heater but I like using the smallest heater that can do the job. I don't want a 1'500 watt heater blasting out super hot air that might damage the tent, toast roots or burn leaves.