I have just started to learn about growing under lights. I have a 4 bulb, 4 foot fixture with T5 grow lights. I set it up, filled a tray with seed starting mixture, watered it, put on the dome and turned on some bottom heat. The Fixture hangs just above the dome. Before I put any seeds in, I wanted to see how warm the soil was going to get. I don't have a thermostat for the heat mat; and I'm not sure I want to invest in one now.
So I let it be over night; and measured the soil temp in the morning with a water/meat thermometer that I trust. It read 114 degrees! So I unplugged the heat mat and let it stay set up like that for the day. I got home this afternoon and measured the soil temp at 94 degrees. Yikes! Now, I've got a small fan running on the area; but I'm not super hopefull because the dome is going to block most of that air movement.
All my seed packs (all flowers), say to have temps at about 75 degrees for germination.
Is it normal for things to be running this warm?? This is the fixture I have: