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Greenhouse Heaters

What Options For Your Greenhouse Heater?
There are several types of heating methods suitable for greenhouses. Warm air heating is perhaps the most suitable and economical for the average greenhouse owner. Other options do exist but they are mainly warm water pipe heater systems which are very expensive to install. An electric greenhouse heater has many advantages. They are comparatively cheap to install, they can easily be moved, they provide all the additional benefits of air circulation and they provide a very quick response to sudden changes in temperature.



Almost all electric greenhouse heaters come with a thermostat and this is an essential feature. Easily available heaters for small to medium sized greenhouses are 1,250 watt (1.25k W), 2,000 watt (2k W) and 3,000 watt (3k W). If you want to relate these to heating costs, then the respective Btu (British thermal unit) values are:

1,250 watt 4.3 Btu

2,000 watt 7.6 Btu

3,000 watt 10.2 Btu

There are a couple of disadvantages with an electric greenhouse heater and they relate to the fact they do not distribute the heat as evenly as warm water pipe heating systems. This results in cool spots in the greenhouse which occur in corners and areas which are are in the direction of the warm air being blown by the heater. It is best therefore to have two or more electric heaters in a greenhouse so that the area heated is maximised.

The second disadvantage of the electric air greenhouse heater is that any plants in the direct flow of the blown warm air may suffer damage from loss of moisture and too high a temperature. Consider this carefully when positioning your electric heater in the greenhouse. Plants on benching will not be affected because the heater can be placed on the floor and well below the plants on the benching.


First decide which power you require for your greenhouse heater - we would recommend you go for a 2,000 or 3,000 watt heater. If these have a thermostat then there seems little benefit in going for the lower power models. Anything more powerful than 3,000 watts will significantly increase the risk of damaging plants through too much heat or water loss.

It's quite common on greenhouse heaters to have adjustable fan strengths (high or low are normal) and a feature to blow unheated air. These features are worth having and they will not increase the cost significantly. One final point before considering which model to choose is safety. Always select electric heaters designed specifically for greenhouses. Household heater models are not safe in the greenhouse.



We have looked for models of greenhouse heater available online and we recommend one company particularly for buying online, Harrod Horticultural. They offer safe, well-designed models of electric, paraffin and propane greenhouse heaters. They have been established for several years and will provide a reliable service. Click here to view or buy greenhouse heaters online. They also an excellent range of greenhouse insulation products which will significantly reduce your heating costs.

When considering the economics and cost of greenhouse heaters also consider soil-warming cables. These considerably reduce the requirement for greenhouse heaters. Finally, dont forget the obvious, only heat the part of your greenhouse which you need at any one time. Partioning off a section of your greenhouse and only heating one part of of it will greatly reduce the cost of greenhouse heating.


If you don't have an electric supply to your greenhouse then a propane gas heater is probably your best option. The key advantage is that they do not require electricity. They can however be bulky and they do give off carbon monoxide. Condensation can also be a problem with propane gas heaters. For both reasons you need to make sure that that propane greenhouse heaters are only used where there is adequate ventilation.

Another disadvantage of propane greenhouse heaters is that they don't have a fan and therefore heat distribution can be uneven resulting in cold pockets. But if you have no electricity then a propane gas heater is your best bet. It's probably wise to keep plants in your greenhouse which only require frost protection in the coolest winter months.