Large Electra Grow Heat Mat
The wire grid holds the flats 1 1/4 inches above the mat. The surface temperature of the mat ranges from about 15 to 20 degrees F above room temperature. It's a little tricky on sunny days, so I added a timer. Now the heat mat is only on from 5pm to 11am. I use this from December through March to germinate seeds. I also set my Geranium cuttings near by to take advantage of the radiant heat. A grow light is suspended above to assist germination during the grey cloudy winter days.