Pretty well regardless of where you live in the USA or Canada, at least at some time during the winter, you’re more than likely going to have to consider heating a greenhouse to protect your treasured and prized plants.
Depending on the plants you keep in the greenhouse, the greenhouse heaters might only need to keep the temperature above freezing, whilst other plants may well need a certain constant minimum temperature for them to thrive later on in the growing season. Needless to say there are a range of greenhouse heaters and systems suitable to meet your requirements.
Economical Greenhouse Heaters
There can be little doubt that the most economical greenhouse heaters to run are those that use either a liquid fuel like kerosene or bottled gas like LPG/Propane. However, liquid and gas fueled greenhouse heaters do have several drawbacks.
The first disadvantage is that you’ll need to make fairly regular visits to the greenhouse to keep checking that the fuel hasn’t run out; which, if you need to use the greenhouse heater a lot, can become tedious.
Secondly, any burning fuel creates condensation and, in the relatively confined space of a garden greenhouse in which you obviously won’t want the vents open – a lot of condensation can quickly occur. Perhaps of lesser importance is also needing to check that the wick is burning properly and the need to keep the burner parts clean. Also, ideally you really should have a flue/chimney for any waste gases to be vented through.
Solid Fuel Heat for Heating a Greenhouse
Perhaps the least common type of greenhouse heater is a solid fuel one burning coal, wood, or possibly even peat if available locally. Small solid fuel greenhouse heaters can be inside the greenhouse, but will require a chimney to be fitted and will simply heat the surrounding air.
Alternatively, they can transmit their heat by heating water that passes around the greenhouse in 4 inch pipes. The same as for liquid and gas greenhouse heaters, you will still need to regularly check that the fuel doesn’t need topping up.
Electric Greenhouse Heat
Electric greenhouse heaters can win over their rivals simply by being the one type that you don’t need to be regularly checking on. They’re all thermostatically controlled to help both keep that all important even temperature and not waste fuel. You can have an electric green house heater that is simply a heater or one that also has a fan to blow the heated air evenly around the greenhouse.
Should you wish to you can install under-soil electric heaters in your greenhouse to ensure that every plant gets the same amount of heat delivered to it, These under-soil heaters are more efficient than any other type of greenhouse heater as they are not wasting energy heating air, but only heat the plant directly via the earth it is growing in.
Other Points to Consider
Apart from the points already mentioned, the following are other points to consider about your choice of greenhouse heaters. Electric greenhouse heaters do have several advantages over the other models, but the one big drawback for them is that they are the most expensive to run, unless you have access to a very cheap energy supply. Speaking of which, although expensive to initially install, if you have your own wind turbine generating electricity or a geothermal heat pump, then you can heat your greenhouse incredibly cheaply.
Although modern liquid, gas and solid greenhouse heaters can all be thermostatically controlled these days, having thermostatically controlled ones will add to the overall cost as you’d have to run an electric line out to the greenhouse, which means getting a qualified electrician to do it for you, being an outdoor connection.
Photo by flickr user Wendy Piersall