Today’s weather forecast is 100% chance of rain. Sad emoji.
At this point in winter, I rarely interact with our garden except to peer at it wistfully from indoors. But now we have an intermediate space — our sunroom — that is nice and dry and usually a bit warmer than the outside temperature. But it needs to be even warmer than that for plants. This will be our first winter using the space and I want to figure out just how much heating power we need to maintain a minimum temperature for the indoor plant forest that I’m slowing building.
Minimum Sunroom Temperature
My low-temperature goal is 55 degrees. This seems reasonable to me given our average temps in the coldest months are highs in the upper 40s and lows in the upper 30s. My 55 degrees goal is a quasi-informed threshold based on a little plant research plus my desire to not have our electric bill shoot through the roof. And safety is key. I’m highly suspicious of space heaters and I don’t want our house to go up in flames all in the name of keeping a few plants warm.
So to start, I installed one 400-watt ceramic wall heater middle of the room, connected to a plug-in thermostat that kicks on when the ambient temperature hits 55 or below. The heater is sturdy (mounted with screws to the wall) and seems pretty safe. But it’s also low-powered – think four, 100-watt light bulbs. It’s really meant to act as a supplemental heat source for chilly rooms inside your house. I have seen the thermometer read below 55 during sub-freezing days and nights, and have had to migrate some sad plants indoors. So I’m considering adding a second 400-watt heater or upgrading to a 1000-watt version of the same type. If you have a newer, better-insulated sunroom, you may get better results with less expense. We are contending with an uninsulated roof and single-pane windows.
Low-Temperature Indoor Plants
I’m trying to limit my collection to plants that tolerate low temperatures, using 55 as a general cutoff. But even if the thermometer reads 55 degrees, areas near the floor and windows will be colder. So in reality, my plants are all guinea pigs. I’m watching them carefully to see how they react. I recently moved a wilty Teddy Bear Vine and another mystery plant indoors. I’m keeping my fingers crossed that they recover!
Sunroom Heating setup
Successful Cold-hardy Indoor Plants
Indoor Plants That Need More Warmth