I was getting ready to throw away an old Coleman camping cooler and happened to set one of my propagating mats on top of it, and I had a BFO (Blinding Flash of the Obvious) and got to thinking that I might be able to place a propagating mat in the bottom and run the power cord out the drain hole (and keep it from flooding) and then set my rootrainers/flats inside the cooler.

With it being so well insulated, and having a attached lid, this would give me the ability to set the cooler outside over the "winter" months (or what passes for winter here in the mid-south).  It would give me constant bottom heat to the root zone, and on days it's above freezing I could leave the lid opent to keep the tops cool/cold, but provide natural sunlight. On cold nights close the lid entirely or leave it propped open just enough to keep the tops from freezing.

Thoughts?

I like the idea - always looking for a cheap way to do things - though I would want to see 65+ degrees temp inside the cooler (heater?) 24/7. Sun isn't that important to the rooting process. It should be small enough to put in the garage, or a family room, or ? through the winter.

So far, so good! Overnight low 31°F
Internal soil temperature inside closed heated cooler 80°F
On nights that do not get below freezing, I keep the lid either open or partially closed.