The greenhouse is essentially a shed frame, clad with polycarbonate panels. It was built in the spring of 2011, so I’m still learning how to use it to best effect. One of the challenges is to heat it enough so that the plants being overwintered survive, without breaking the bank!
The greenhouse is heated by a portable electric space heater controlled by a thermostat that turns the heat on at 40 degrees. The polycarbonate panels are single walled, so I’ve been adding plastic sheeting to the inside walls to provide a second “skin”. I’ also have two trash cans filled with water, along with numerous other containers filled with water to provide thermal mass and residual heat. So far, the heater has been keeping the temperature about 12 degrees warmer than the air temperature. This is fine until the temperature starts dipping below about 20 degrees.
Last night the temperature dipped to 18 degrees. I covered the more tender plants with row covers and blankets. Ellen suggest I turn on a shop light to supplement the heater. Voila! The greenhouse bottomed out at about 38 degrees. Not sure what I’ll do if/when it goes below 15! But clearly I need a more powerful heater, and a backup plan for a power outage…
What is the best type of Greenhouse for my use? Will I need to heat my greenhouse in the winter?