Realsis, I use a reptile heating pad, I expect the same thing you use for your seedlings and tortoises.
Blooie, I initially made the cave from welded wire (hardware cloth) wrapped wth jute, but then I thought when there was a breeze in my greenhouse it got cold fast. The cardboard box is really well insulated and unexposed.
Blooie, I initially made the cave from welded wire (hardware cloth) wrapped wth jute, but then I thought when there was a breeze in my greenhouse it got cold fast. The cardboard box is really well insulated and unexposed.

. We have some old oatmeal that we got before we found out that oats grown where wheat has been grown can pick up wheat gluten. DD1 is intolerant. So when it is really cold I sometimes make the working girls breakfast (only time this year). Today it was oatmeal, old wheat based pasta a bit of meat scraps and fat and about a half cup of BOSS. Took that down at 11 AM when it was merely -7F and laid out the fare for the girls. As you can see it was about 0F in the barn (click the pictures to get the full size ones): 