A couple of years ago I built a dry root cellar in our basement in order to keep vegetables and fruits over the winter. I framed in a corner of our basement, put in a door and used a window to give the room access to the cool air from outside. Last year I acquired a half dozen refrigerators in order to store spawn and fresh mushrooms. I decided a walk-in cooler would be more efficient and convenient, so I decided to make our root cellar also work as a walk-in cooler.
The walk-in cooler is essentially complete now, after working on it on-and-off for a couple of months. This just in time for my first order of spawn that came in yesterday – about 100 lbs. of shiitake sawdust spawn.
I started the work in December by papering (can that word be used here?) the walls of the root cellar with rigid insulation, enough to give the room an R-value of at least 20. I didn’t screw the insulation into the walls behind. Rather I just cut the pieces tight enough so that they would stay put.
This photo was taken just outside the root cellar/walk-in cooler. While I used pink insulation for the bulk of the insulating value, I finished it off with the yellow insulation with a foil face, since this surface will shed the condensation that occurs in this type of environment. I also taped all the seams with foil tape and spray-foamed around the receptacles. Unfortunately the yellow insulation in particular is not an environmentally friendly product, but I couldn’t think of a good alternative. Please comment if you have any thoughts about this.
I put insulation on the floor and I used self-tapping screws with a rubber gasket to attach the insulation to the ceiling. Here is a photo of the wood threshold I put in that shows how much I built up the floor. After putting in the threshold I put down some painted plywood sheets in order to protect the floor insulation.
Finally to the fun part! I put in the air conditioning unit that will work in the warmer months and the vents that will bring cool air inside in the winter to cool the space.
Finally, I insulated around the window and hooked up the coolbot, a device that tricks the a/c unit into staying on to cool below the temps it would usually go. My thermostat is currently set at 38 degrees, or about what a refrigerator runs at. So far it is staying at that temp, or a bit cooler.
Growing mushrooms is such a fascinating process, especially with how much temperature and humidity impact their development. Maintaining the right climate is essential for healthy growth, and that’s why I see the value in a commercial smart thermostat. Precise environmental control can make all the difference in optimizing conditions for consistent, high-quality yields. Whether managing a small farm or a larger operation, having an intelligent system that adjusts temperature and humidity automatically ensures efficiency and reduces energy waste. Just like in nature, balance is key—and with smart climate solutions, it’s easier to create the perfect conditions for thriving mushroom cultivation.