I wasn’t sure how to title this. Ha! Okay, the clay pot heating solution is no more. It simply wasn’t enough so I had to switch to “plan B.” I am currently using the Fire Bowl from the front porch. It runs on small cans of propane and lasts for about 6.5 hours.
It may not be the best solution because of the open flame, but it’s all I have right now. I have it resting upon the paving stone in the centre of the greenhouse, away from the plants from all sides. It is set on the lowest flame possible so that it will last through the night. Within minutes the inside temperature rises to 16 c. / 61 f. and maintains this temperature through the evening. The propane runs out around the time the sun begins to hit the greenhouse.
The cost of the small propane cans will add up over time so I will investigate how much a larger size propane tank will cost and how long it would last and how much it will cost to refill. I found a propane heater with a thermostat so hopefully this will regulate how much propane is used thereby extending time before refills.