Many people avoid getting a greenhouse because they fear the additional electricity costs. It can be tough to pay energy bills in the current circumstances (especially when Covid-19 was still around the town). So, how to heat a greenhouse in winter using energy-efficient solutions? Fortunately, some clever tricks can be cost-saving and keep the plants under the above-freezing temperature.

One trick, for example, is choosing a design that can maximize the sun’s advantage. People with limited resources should choose a greenhouse design that can absorb most sunlight whenever available. These options can lower the need to use electricity to heat your greenhouse. Moreover, there are a few more solutions besides absorbing sunlight, which we will discuss later in this article.

#1. Making Compost Inside The Greenhouse For Extra Heat

Every gardener needs compost and has probably noticed that it is usually quite warm when you dig it up. That is because the decomposition of vegetative matter causes an exothermic reaction. In short, when any plant material breaks down, it will generate heat.

Sometimes a compost pile can get as hot as 100°F and maintain that temperature if we turn it over regularly for oxygen. Therefore, making compost inside the greenhouse offers the added advantage of keeping the greenhouse warm.

You can also add wood mulch or kitchen vegetable waste to the sides of the path or the potting beds. This way can also add natural heat to the greenhouse. It also turns the conservatory into an eco-friendly potting shed.

#2. Use Heat-Absorbing Materials

Thermal mass can be beneficial while passively heating the greenhouse with solar energy. Objects like bricks, clay, and rocks can absorb the heat from the sun and release it into the air slowly once the temperatures start going down at night. Water can also trap heat and dissipate it slowly inside the greenhouse environment.


You can consider choosing a design such as a dwarf wall to add thermal mass to the greenhouse. The limestone rock is another option to retain the ground’s warmth. Some gardeners place black water barrels inside their greenhouses to keep the daylight’s heat after sunset.

#3. Add Double-Pane Glass

Even houses in icy locations tend to have windows with double glass panes. Double glass panes allow the sun’s heat to come in during the day and minimize heat loss at night.


If you find the double-pane windows costly, you can add a layer of plastic or bubble wrap next to the glass to create the same effect. Some people even build a mini greenhouse inside their big one using plastic sheets to keep the heat longer.

#4. Insulate The Northern Side

It does not make sense to have glass on the northern side of the greenhouse for people living in the northern hemisphere. The greenhouse will never receive any sunshine from the north, so it is best to insulate that side.

That way, the greenhouse will lose less heat and stay safe from the freezing northern winds during winter. People who consider getting a lean-to greenhouse should always install it on the southern wall to stay insulated on the north side of the greenhouse.

Gardeners can also consider painting the south-facing interiors white or covering them with reflective metal like tin. That way, the sun rays will bounce from the wall onto the plants and potting beds, allowing more sun and warmth during the day.

Read more: The Benefits of Greenhouse Gardening

#5. Sink The Floor

Most people think that basements are colder than the rest of the house. But underground spaces can be much warmer than the surface temperature during winters. So gardeners can consider sinking the greenhouse floor below the surface to maximize heat retention if possible.

The warm earth can keep the greenhouse temperatures moderated and prevent the garden beds from freezing at night. Greenhouse owners can also consider adding solar-heated water pipes under the potting beds to keep them warm overnight.

Final Words

These methods may not be sufficient to keep a greenhouse in a tropical climate. But they can keep the insides warm enough for plants in temperate climates. Gardeners can also use these tricks to grow certain fruits and vegetables through the winter without adding to their energy bills.


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