Heating is necessary in your greenhouse in winter if you wish to keep it frost free, except of course if you live in certain southern regions. If you have a tropical greenhouse, heating will be useful for most of the year, as this type of greenhouse requires an average temperature of 20°C.
Choose your heating system according to the surface of the greenhouse – you don’t heat a 10m² greenhouse in the same way as one measuring 100m².
Electric radiators are the best suited to small surfaces. However, make sure to use special greenhouse heaters, as these are waterproofed and therefore correspond to this type of usage.
These radiators use hot air for heating, but ones which radiate heat using infrared lamps also exist and can be hung from the roof of the greenhouse. This type of heater is used for surfaces of less then 6m² and a portable model also exists.
Tubular radiators can be installed along the sides of the greenhouse, but these are bulky and not easy to install.
For bigger surfaces, a hot air generator can be useful. The level of air blown out can be adjusted by an atmospheric thermostat and certain models are remotely controlled. These are the top-of-the-range models of electric heating.
Used both as a back-up heater for small surfaces and for cold greenhouses, this type of heater is easy to install, transportable and economical. Be careful, however, to use sulpher-free petrol, as the presence of sulpher may be toxic for certain plants.
As this type of heater doesn’t have a thermostat, it needs to be closely monitored. Make sure to fill it regularly, though some models can run for 7 days without being refilled.
Town gas isn’t used for heating as it is expensive and difficult to install. Gas heating is thus caried out by Propane gas in bottles. Butane is not suitable as it is too sensitive to frost. Recent models are very safe and are leak-proof.
Gas heaers are 30% more economical than petrol heaters and some models are equipped with a very useful thermostat, which can be adjusted according to your needs. Gas heaters also offer more autonomy than petrol heaters.