Except I don’t live on 10th Avenue, and Bruce Springsteen was not available to lend me a hand with this Southwest Michigan crisis!
Because I only thought, researched, and planned, and did not act, I opened the greenhouse Saturday only to find that everything in there—and I mean EVERYTHING—was frozen solid. Every pot of dirt, the tomatoes, the 55-gallon barrel of water in the corner… solid ice.
I sat down on a VERY cold chair and thought about how I was going to remedy this situation! I decided that a slow thaw was the way to go. I brought my old oil heater out of the basement and set it up next to the solid barrel of ice. After a trip to the World’s Surliest Ace Hardware for a thermometer, I saw the damage: less than 30 degrees.
The “Small but Mighty” Greenhouse Heating Strategy
Sunday morning, I hit Lowe’s for concrete blocks and a small forced air heater. If you’re gardening in Michigan Zone 6b, you know that heat is only half the battle; you need air circulation to keep that warmth moving.
I set the oil heater next to the “iceberg” (the water barrel) and set the forced-air unit blowing diagonally across the space. Safety was clutch, so I used a high-rated extension cord and ran both heaters on low to avoid sparks. I blocked the vent louvers with the concrete blocks to bar that cold.
By Sunday afternoon, the iceberg was finally starting to give up a little ground. It was still pretty solid, though. At this point both heaters had been running on low all day.
Turning the Tide with Thermal Mass
I left them both on low overnight Sunday and Monday morning the barrel was thawed more, and we gained a couple degrees. I unplugged both heaters when I went to work because I was concerned about safety.
Monday after work I came home and unplugged the oil heater and left the forced air heater on high overnight. This morning I decided to leave it on all day. Imagine my joy to come home to find how balmy it was in there! That forced air heater is small but mighty!!
I have an aquarium heater coming soon. Once that 55-gallon barrel is warmed up, it acts as a thermal mass radiator, which will regulate the greenhouse temperatures overnight and ensuring that “iceberg” never returns. The tomatoes are toast, but I have high hopes for my greens and herbs. They’re cold tolerant anyhow, and I’ll have things figured out by the end of the week to where I can put the forced air heater on a timer to run on low overnight.
Lessons from the Michigan Cold
I know I need to figure out the cord situation. Right now the door is cracked a tiny bit for the cord and that’s less than optimal. I may drill the smallest possible hole in the side of the greenhouse and use spray foam insulation to seal it up some but still allow for some room for cord movement. I’m open to suggestions.
So that’s what I’m up to, trying to make this a functioning greenhouse in Zone 6b southwest Michigan. I’m learning, and by next winter I’ll be an old pro!
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