Heating a Greenhouse in Winter

Your joy of gardening does not have to go dormant during the winter. A greenhouse is a good way to continue the process all year ‘round. However, many climates in the country can be bitter cold during the winter and there could be a need to provide some extra warmth for the greenhouse.

This can be achieved using solar-heated water, electricity, or even kerosene or propane.

A passive solar greenhouse. (Courtesy: The First Awards at flickr.com)

A passive solar greenhouse.
(Courtesy: The First Awards at flickr.com)

Heating With Water

For those of you who are committed to promoting sustainable energy and wish to save some money, you might want to look into heating your greenhouse using water and the sun.

In this case, you need to plan ahead a little. Take a few moments in the spring and summer to gather plastic bottles and jugs and keep rather than discard them for recycling. Be sure to rinse out these containers thoroughly and be certain to keep the bottles’ and jugs’ caps and lids. Store the collection somewhere until winter.

Just prior to the onset of winter measure the inside of the greenhouse wall that receives the most sunlight per day.

Measure the jugs and bottles and calculate how many you will need to cover the wall. Adjust the shelving to permit the stacking of the jugs and bottles along the wall. It may be necessary to purchase or build more shelving.

Fill the jugs and bottles with regular tap water and add a bit of black dye to the liquid. Gardeners who have used this method to heat advise that you use Rit fabric dye. It doesn’t matter whether you use the powder or liquid form. Add just enough of the dye to turn the water black and then cover the bottles and jugs with their caps and lids.

Stack the water-filled jugs and bottles against the sunniest wall. It’s best if you cover the entire wall or at least two-thirds of it from bottom to top.

During the day the water will absorb the heat generated by the sunlight and then at night the water will release the heat and warm the interior of the greenhouse.

Heating Using Electricity

This may not be the cheapest way to assure that the greenhouse plants remain warm during the winter, but it is effective.

Measure the distance between an electrical outlet outside or inside your home to the greenhouse and purchase a heavy-duty power cord of that length from the neighborhood hardware store.

Route the cord from the outlet to the greenhouse.

Before winter arrives, dig a shallow trench next to the greenhouse that goes up through the base and into the floor, route the cord through and then cover with dirt. This will help ensure that the greenhouse remains insulated during the winter.

Purchase an appropriate heater. There are heaters specifically designed for use in this application. If you can’t find one, then measure the dimensions of the greenhouse and check with a hardware store salesperson for the appropriate size. Usually, the smallest heaters will suffice. Adjust the heat setting in accordance to the heater’s directions based on the greenhouse materials. A greenhouse made of poly sheeting will probably require lower heat than one made of polycarbonate or glass.

Heating With Kerosene or Propane

Keeping your greenhouse warm during a deep freeze can also be achieved using propane or kerosene.

Purchase a gas-powered heater from a garden or greenhouse supply company.

Next, be sure to read the instructions that come with the heater. You may discover that you will need to vent the greenhouse when the heater is running. Proper venting is essential to prevent a build up of fuel exhaust that can be hazardous to one’s health.

Refill the gas tank when necessary.

About Robert Janis

Written by Robert Janis for LawnEq - Your specialists for Lawn Mower Parts and Small Engine Parts. We offer genuine premium OEM parts for Land Pride, Toro and many more dependable manufacturers.