One of the challenges with our greenhouse has been keeping it heated during the winter. Currently, I use a combination of methods to heat ours. I have two 1500 watt electric heaters, one Big Buddy Propane heater, and a 119-gallon heated solution tank. The solution tank heaters usually run all winter. They keep the irrigation water for the plants at 72-78 degrees. For temperatures 22 degrees and above, I typically use only the two electric heaters. The propane heater is more for temperatures below 22 degrees and when there is a winter power outage.

Our winters are usually relatively mild in North Carolina. Our lows get no lower than the upper 29-25 degrees Fahrenheit. However, during the past 2-3 years, we have been getting more arctic blasts from up north. These arctic blasts can bring temperatures down to as low as 9 degrees Fahrenheit.

If the arctic blast lasts only one night, it can be managed with only my propane heater, heated tanks, and the residual heat absorbed by everything in the greenhouse during the daylight hours. It becomes a problem when we get multiple days like this. Usually, on those days, the temperatures never get out of the 30's eliminating any residual heat from sunlight during the day so the heater and storage tanks have to do all the work of trying to keep the greenhouse above freezing.

I am always looking for new ways to manage this issue. In the future, I am planning to install a temperature switch on the pump in the heated tanks. I would have the pump set to turn on a few degrees above freezing to circulate the heated water to the plants to help protect them from the lower temperatures.