Margaret Lauterbach

How to heat and cool your greenhouse in winter

Build a tea lighter heater for your greenhouse.
Build a tea lighter heater for your greenhouse.

Margaret is taking a break during winter from her column. This column ran Oct. 15, 2016

The cost of greenhouses has lowered quite a lot, and if you’ve bought one, you face the problem of heating and cooling it in winter.

You can physically open windows at or near the roof to let heat escape if you don’t want to hire an electrician to set up thermostat controls and an exhaust fan, but heating it on cold days is a different problem. has several clever ways to heat areas using tiny tea lights and flower pots in specific configurations. On the youtube site, search for: tea light heater.

Our winter sun is quite bright and hot enough to raise the interior temperature of a greenhouse to over 100 degrees, even when there’s a foot of snow on the ground. Lest you cook your greenhouse plants, your greenhouse does need cooling, even in winter.

If you’re new to this area, our winter sun appears fairly low in the south, so situate your greenhouse to take advantage of that.

Straw bales make great mouse houses

If you grew plants in straw bales this year, be aware they make great mouse houses, warm and cozy for those four-footed predators. If you don’t want to shelter them, deconstruct the bale, adding it to your compost pile. In my yard, at least, mice and voles haven’t used the compost pile for winter shelter. In spring mice can and will feed on tiny seedlings, foiling your efforts to raise specific varieties of plants for your own use. They’re quite destructive in the garden.

Winterizing your garden involves tending to your compost pile. Ideally, turn it and turn a hose on it for a bit. Then have your sprinklers blown out before we have a freeze that breaks your sprinkler system.

Some folks use spray products to repel spiders this time of year too. Spiders are valuable workers in your garden, so there’s really no need to spray there or around the perimeter of your yard. If you don’t want them in your house, spray around the foundation only. Spraying the perimeter of the yard may kill ground-dwelling bees and other helpful creatures, in addition to the micro-herd in your soil.