If you use a heating pad for starting seeds, you need to keep a watch at the temperature of the soil. I measured over 90F in the center of the tray and over 84F at the corners. This is with the plastic dome on and the shop lights switched on. I used a “instant read” type meat thermometer from the kitchen drawers 😉 Of course this temperature is too hot and this is probably why my impatiens seeds are not germinating.