The electric heat mat raises the temperature to 10-20 degrees over the room temperature. My green house is in my basement where the temperature is 55 to 60. I have seeds sprouting in four days. The question which I have when I should remove them from the heating pad. I am thinkg when they reach 1/4 inch I am not sure.

linnea56, I keep my house a lot colder than that, 54 at night or during the day when I'm gone to work, 58 when I'm home, actually now it is down to 56. I thought I might have trouble with peppers germinating but they started coming up in 7 days. I think what helped me is I used a piece of pink rigid foam insulation slightly bigger than the mat, I cut out a section for the plug so that it laid flat. Reviews I read said it helped direct the heat up into the tray instead of warming the surface the mat was sitting on and it seems to have worked well for me.

I like to place a thermometer in the tray. I have had a radio shack indoor-outdoor one for years, the one with the electric wire. Depending on what the tray is how the heat is conducted. All ao if the mat is on a metal (like a file cabinet) the heat will be less than on wood or a cardboard insulator. Lots of ways to vary the temp to what you want.

Although I am not in the market for a heat mat, I looked around and could not find one with a built in thermostat. Twenty years ago I was able to buy a heating cable including an inline thermostat, much like in your electric blanket, it worked fine for years when I gave it away. I just don't see how without a thermostat to control the temperature, I could use a heat mat. When I needed a bigger bottom heater, I made my own using a rain gutter defrost cable 300 watt heating an aluminum 10 guage sheet 3x6 feet. A separate adjustable thermostat was added, but is seldom set for more than 70 degrees. My bottom heater is in my unheated greenhouse which in the winter varies in temperature from 45 to 70 degrees. When the air temperature is over 60 degrees no additional heat is detectable from the bottom heater. Al

Thanks! I was thinking about what to put underneath it, too. I save all those sheets of Styrofoam that come with a shipped box, I was thinking about using those.

Is there is list somewhere that says what temperature various seeds like to be at? It's been a long time since I've started from seed. I'd like to start caladium bulbs to get a head start, and mostly flower seeds. 80-90 degrees would be great for caladiums.

I found this site helpful.

Here is a link that might be useful: Cornell growing guide