Greenhouse heaters and frost protection
Most UK gardeners heat a greenhouse for one reason: to keep it frost free, so tender plants such as pelargoniums, citrus and young plants get through the winter. That needs far less heat than keeping it warm. An electric fan heater with a thermostat switches on only when the temperature drops, and bubble insulation on the inside of the glazing cuts the heat you lose.
Bio Green Palma 2kW heater
Electric fan heater with a digital thermostat, built for greenhouse use
£170 at Amazon · 4.3 stars (210)
LightHouse 2kW greenhouse heater
Cheaper fan heater with temperature control for small and medium houses
£44 at Amazon · 4.2 stars (432)
Elixir Gardens bubble insulation 1.5 m x 20 m
Enough bubble wrap to line a 6x8 greenhouse and cut heat loss
£41 at Amazon · 4.6 stars (98)
Elixir Gardens bubble insulation 1.5 m x 10 m
Smaller roll for a lean-to or a 6x4
£23 at Amazon · 4.4 stars (169)
Prices and ratings from Amazon.co.uk when we checked. Affiliate links. We have not tested these ourselves.
What to look for
- Set the thermostat just above freezing for frost protection. Every extra degree costs you more electricity.
- Line the inside with bubble insulation before the first frost. Fix it to the frame, not the glass, and leave the vents free.
- Only run an electric heater from an outdoor socket protected by an RCD, and keep the plug away from water.
- Paraffin heaters work without a socket, but they give off water vapour and fumes, so you have to open a vent a little while they burn.