Advice
RHS Help & Advice
Greenhouse heaters
To grow greenhouse plants successfully it is important to provide and maintain suitable temperature levels throughout the year for the specific plants being grown.
Select heaters with sufficient output to maintain the required minimum winter night temperatures efficiently, taking into account installation and running costs.
Electric heaters
These provide the most adaptable source of heating for smaller greenhouses and the most efficient means of maintaining specified temperatures. Thermostatic control ensures no wastage of heat in changing external conditions. There are no fumes and no need for ventilation when the heaters are in use.
Moveable fan heaters or fixed tubular heaters are both effective heat suppliers, fans providing moveable sources of warmth for sectional greenhouses (and changing crops). Installation may be somewhat expensive, but do not use an extension from a house or outbuilding.
Gas heaters
Gas heaters fuelled by bottled and natural gas (from the mains) are less efficient and convenient than electric heaters. They discharge the products of combustion into the greenhouse atmosphere and some ventilation is required. Thermostat settings may be less precise. A safe place is needed for gas cylinders, which need regular monitoring and replacement.
Paraffin heaters
These provide the most basic means of greenhouse heating. They need frequent re-filling and wick-trimming; the need for fuel deliveries and storage are further disadvantages. Paraffin direct discharge heaters release water vapour and fumes into the greenhouse as they burn and some ventilation is important, (reducing heating efficiency); but they are useful for reducing the risk of frost damage in smaller greenhouses and as an emergency standby.
Further information
Energy conservation in greenhouses