This is the finished product. I capped our walk-out basement stairs with a very simple greenhouse made of scrap wood and 3 mil painting dropcloth. This should help me extend the season a bit.
Just open the door from the laundry room and you’re there.
This afternoon the outdoor high reached 42. The greenhouse was 81. It seems promising. I’m going to start some butter crunch lettuce seeds in the containers on the steps in the pictures. I just need to figure out what to do about nighttime freezing. I wonder how much help a 5 gallon bucket of water warmed with an aquarium heater would be?