Germination box
When i was just starting with farming i initially used heating mats big enough for 1 flat. After 2 wasnt enough and i needed like 8 or 10 flats on a heat mat at once i decided to build one.
I decided 12 flats would be enough for a germination box. I could always build another one if i needed it. I measured the dimensions i needed for 12 flats to fit on my bench system in the greenhouse. I added an extra couple inches for ease of getting trays in and out and then built a box out of plywood. I then added eaves trough melter cable as evenly as i could on the bottom of the box. Finally covering the cables with a layer of sand to help even out the heat hitting the trays.
The cable is plugged into one of the inkbird controllers i use for everything (multiple uses for each item) and set to 75 degrees.
Lastly i built a frame lid and put greenhouse plastic on it so that it closes all the way
The result is i can set the temperature in my greenhouse to 12 degrees celcius and my warm weather starts are unaffected. The cost saving of the lower temps in the greenhouse are quite significant.
This same box has worked for the past 4 seasons. I had to replace the plastic on the lids once as they got stored badly one summer and were damaged. I have rarely needed more than 12 flats in the germination box at a time with my staggered start for my summer crops.
Sage peasant 