Garden & Lawn

Top 7 Best Greenhouse Heaters, how to choose the right one and Reviews

Last updated on May 11th, 2021

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You’ve gone to such trouble to build a greenhouse to create the perfect environment for your plants, from seeds through to insulation. But do you have a greenhouse heater to ensure that the greenhouse air temperature is the correct warmth in cooler days and nights (and the correct coolness on warmer days and nights)? And it’s not just the time of year you need to worry about. In their different growing stages, plants often need to be in differently heated air. And it’s usually not the same for diverse species of plants. Yes, it’s all very complicated. But your starting point is to decide which greenhouse heater suits your needs.

That’s where this review of the Best Greenhouse Heater comes in. We look at a selection of heaters – electric, paraffin and gas-powered – and explain the pros and cons of each one, along with their best features and our recommendation. Our Buyer’s Guide goes more in-depth into the standard features the best greenhouse heaters have.

Thermostat for checking greenhouse heater is keeping greenhouse as consistent temperature.

Our Best Pick for greenhouse heater is the Bio Green PAL 2.0/GB 2KW Palma Heater with Digital Thermostat. This electric heater allows you to control the temperature adjustments in your greenhouse all the way from frost protection to +99°C. The air circulation rate ensures that the environment remains extremely healthy for your plants.

The Botanico Greenhouse Heater is our Runner-up choice. While this heater doesn’t have the sophisticated temperature controls of the Best Pick, it does offer a choice of two power levels, at 1KW and 2KW, ideal for at least keeping your greenhouse first free and warmer than outside. In addition, you can use the fan without heat to just circulate the air which helps prevent rotting.

BEST PICK
Bio Green PAL 2.0/GB 2KW Palma Heater with Digital Thermostat
RUNNER-UP
Botanico 2kw Greenhouse Heater
LightHouse 915mm 135W Eco Heat Greenhouse Heater
Eden Gas Greenhouse Heater 2kW
Title
Bio Green PAL 2.0/GB 2KW Palma Heater
Botanico 2kw Greenhouse heater
LightHouse 915mm 135W Eco Heat Greenhouse Heater
Eden Gas Greenhouse Heater
Pros
Powerful, energy-efficient, compact and safe. Thermostat controlled, maintains the temperature within +/- 2°C, IPX4 Rated splash-proof with fan for better air-circulation.
Affordable with built in thermostat and frost watch feature to protect tender plants
Very affordable to run, perfect for keeping greenhouses above freezing to protecting tender plants
Efficiently keeps the greenhouse at a consistent temperature, thermostatically controlled, no electric needed
Heat output
2kW
1kw or 2kw
135w
2kW
Power source
Electric
Electric
Electric
Gas
BEST PICK
Bio Green PAL 2.0/GB 2KW Palma Heater with Digital Thermostat
Title
Bio Green PAL 2.0/GB 2KW Palma Heater
Pros
Powerful, energy-efficient, compact and safe. Thermostat controlled, maintains the temperature within +/- 2°C, IPX4 Rated splash-proof with fan for better air-circulation.
Heat output
2kW
Power source
Electric
Buy from Amazon
RUNNER-UP
Botanico 2kw Greenhouse Heater
Title
Botanico 2kw Greenhouse heater
Pros
Affordable with built in thermostat and frost watch feature to protect tender plants
Heat output
1kw or 2kw
Power source
Electric
Buy from Amazon
LightHouse 915mm 135W Eco Heat Greenhouse Heater
Title
LightHouse 915mm 135W Eco Heat Greenhouse Heater
Pros
Very affordable to run, perfect for keeping greenhouses above freezing to protecting tender plants
Heat output
135w
Power source
Electric
Buy from Amazon
Eden Gas Greenhouse Heater 2kW
Title
Eden Gas Greenhouse Heater
Pros
Efficiently keeps the greenhouse at a consistent temperature, thermostatically controlled, no electric needed
Heat output
2kW
Power source
Gas
Buy from Amazon

BEST PICK

Bio Green PAL 2.0/GB 2KW Palma Heater with Digital Thermostat
The Bio Green PAL 2.0/GB 2KW Palma Heater is a top-of-the-line electric greenhouse heater with several extremely useful features for the serious gardener. First is its accuracy of temperature control. You control your greenhouse temperature to within +/- 2°C; that should be more than enough precision for even the most temperamental of plants. Then is the temperature adjustment range of -50°C to +99°C. That’s an enormous range within much most, if not all, of the plants you could ever want to grow. This heater is splash-proof with an IPX4 rating so incidental drops of water won’t hurt it or cause it to spark. It can heat a medium-size greenhouse up to 3.6m2 making it ideal foremost domestic greenhouses. If you need almost absolute control over the internal air temperature of your greenhouse, the best of the best, this is the heater for you.

The best greenhouse heaters in our review are:

1. Bio Green PAL 2.0/GB 2KW Palma Heater with Digital Thermostat – OUR BEST PICK

2. Botanico 2kw Greenhouse Heater – RUNNER-UP

3. LightHouse 915mm Eco Heat Greenhouse Heater

4. CrazyGadget Large Paraffin Super Warm Heater Single Burner

5. Biogree WM-P5 Warmax Power5 Paraffin Heater

6. Eden Gas Greenhouse Heater 2Kw

7. Biogreen PHX 2.8/GB Phoenix Electric Fan Heater

RUNNER-UP

Botanico 2kw Greenhouse Heater
The Botanico Greenhouse Heater is another electric heater but without the precision temperature controls of our Best Pick. However, you can select from two output power ratings – 1KW and 2KW – which each have pre-set temperatures to heat the greenhouse too. This works well if all the plants in your greenhouse need the same broad range of air temperature. You can also use the heater fan without heat to circulate the air and cool it down a bit. The frost watch function is a useful feature on this model. It automatically heats the greenhouse just enough to stop the air from being “bitten” by frost, great for tender plants. Your overwintering plants won’t freeze because you haven’t listened to the weather forecast in late autumn. This heater is worth a serious look if you want an affordable fairly basic electric heater for a small to medium greenhouse.

TOP 7 GREENHOUSE HEATER REVIEWS

1. Bio Green PAL 2.0/GB 2KW Palma Heater with Digital Thermostat

BEST PICK

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Bio Green PAL 2.0/GB 2KW Palma Heater with Digital Thermostat

The Bio Green PAL 2.0/GB 2KW Palma Heater with Digital Thermostat is a marvel of temperature control for greenhouses. Its first top-of-the-line feature is temperature accuracy. Whatever temperature you set the control thermostat to, your greenhouse environment will be at within +/- 2 degrees Celsius within that number. If you grow plants in your greenhouse that are extremely sensitive to temperature, this is very welcome news.

The second not-so-common feature is that you can select a negative temperature thanks to the digital thermostat. All told, the impressive temperature range of this heater is 50°C to 99°C which suits pretty much anything you want to grow. It simple terms it’s very accurate and you can pretty much set it to any temperature you need.

As mentioned, this model comes with a digital thermostat that lets you control the temperature accurately. The air circulation rate of 163 m3/h makes certain the air is properly circulated. The digital display will indicate the figures as you go along with your activities. The cord length supplied of 1.9m is sufficient for most greenhouses.

The unit is designed to survive the conditions inside a greenhouse. The design lets the unit sit safely even when you are irrigating. It is splash proof with a splash proof rating of IPX4. However, splash proof does not mean waterproof, so be sure to place out of range of sprinklers or soaker hoses.

The unit has rubber handles and feet to make it easy to use. The handles make it easy to pick up and the feet raise the unit above the ground. This is all to make sure that your space is effectively heated. The unit is not designed to heat up large spaces; rather, it is meant for small compact spaces which makes it perfect for domestic greenhouses but with professional specifications.

The dimensions of the unit are l28cm (width) x 19.5cm (depth) x 31.5cm (height) which means it’s compact with a small footprint. It fits comfortably into a small greenhouse without getting in the way. This is not an inexpensive greenhouse but gives you tight control over the growing environment for your plants. Don’t forget you can also use just the fan without heat to help circulate air to help prevent mould and rotting.

PROS

  • Electric heater with a top-of-the-line features for delicate and fine control of the greenhouse temperature.
  • Very durable with steel outer casing.
  • You can select the temperature adjustment from – 50°C to a very high 99°C using the digital thermostat.
  • Splash proof making it perfect for moist setting.
  • Inexpensive to run.
  • Designed for greenhouses up to an impressive 3.6m2

CONS

  • Quite pricey.

Final conclusion

The Bio Green PAL 2.0/GB 2KW Palma Heater is probably the best heater for a small greenhouse where accurate temperature control is of the utmost importance. The option to choose between fan only and hot air settings makes it a versatile unit to have around.

We love that it can survive water splashes and the moisture levels that are present in greenhouses. The fan makes certain that the air is ventilated to prevent the growth of mould and to keep the plants healthy. The price is a bit high but considering the features offered it is not too bad.

This unit is recommended for small greenhouses. Larger ones will need more heaters (or a larger one) so as to make sure that the heat is able to sneak into every nook and cranny. The only real deal breaker for some will be the price. It is expensive compared to most other models, but the temperature control accuracy and range can’t be beat.

We’ve made the Bio Green PAL 2.0/GB 2KW Palma Heater with Digital Thermostat our Best Pick for greenhouse heater. We like the accuracy and range of its temperature control along with its digital thermometer. If you have a small to medium size greenhouse and plants that are sensitive to temperature changes, this is the greenhouse heater for you.


2. Botanico 2kw Greenhouse Heater

Runner-up

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Botanico 2kw Greenhouse Heater Review

The Botanico Greenhouse Heater doesn’t have the delicate temperature control of our Best Pick, but you do have the choice of heat output of 2KW or 1KW depending on how warm you want the environment in your greenhouse to be. This model has pre-set temperatures and then puts out the appropriate amount of heat to warm the greenhouse air to that level. This amount of power/heat is best suited for a small to medium size greenhouse.

You’re not limited to just heating your greenhouse environment though. If the day comes that you need to give the plants a cool breath of air, the fan can be used to ventilate the area. The ability to circulate both hot and cool air makes this unit more flexible than some other heaters on the market.  

As we said before, heaters that are used in moisture-rich environments need to be waterproof or at least splash-proof. The Botanico Greenhouse Heater is water-resistant with its specifications of IPX4 stated in its credentials. This shows you that it is safe to use in moist environments but not in the direct line of water streams. The unit can be depended upon to provide adequate heat without moisture build-up inside the unit.

The frost watch function is a great feature which heats the greenhouse just enough to keep the frost out. This is perfect for anyone who overwinters plants that don’t need heat but are frost tender and must to be kept just above freezing.

The electric cable provided is only 1.8m long which may be a limit in some greenhouses. If your greenhouse is large, you may need a couple of these units. The dimensions of the unit are 20cm (height), 27cm (width) and 24cm (length). It’s a compact size that won’t get under your feet.

PROS

  • Electric greenhouse heater both heats and cools air depending on what your plants need.
  • Lightweight and sturdy.
  • Build in thermostat for setting the correct temperature.
  • Active frost watch function for protecting tender plants over winter.
  • Waterproof rated for safety.
  • Affordable price and good value for money.

CONS

  • Cannot be wall-mounted.
  • Thermostat doesn’t have many setting choices.

Final conclusion

The Botanico 2kw Greenhouse Heater is a very effective small heater which is perfect for small home greenhouses. It is not designed for bigger greenhouses but you could perhaps run two if needed. This heater’s waterproof rating is not as high as we would like so don’t turn sprinklers on over it. It’s fine for areas that are moist which are everywhere within a greenhouse environment.

The unit is really light weight so moving it around isn’t an issue, even for more mature gardeners. We really like the ‘frost watch’ feature which is great for overwintering more tender plants such as some perennials and young potted plants. 

Overall this little greenhouse heater has all the features needed for effectively heating a greenhouse; it’s reliable, easy to use and comes at a very affordable price. It’s our choice for Runner-up in our Best Greenhouse Heater review. We also noticed it was one of the best selling greenhouse heaters on Amazon with lots of reviews at the time of our review.


3. LightHouse 915mm Eco Heat Greenhouse Heater

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LightHouse 915mm 135W Eco Heat Greenhouse Heater

The LightHouse 915mm 135W Eco Heat Greenhouse Heater works as more of a radiator than the heater. It can raise the temperature of a small space easily so your greenhouse has a consistent temperature. The tube design provides direct heat to the internal environment while keeping the plants healthy. This is best environment for plants that are still at the growing stage and need constant and reliable heat, but a regulated amount. This heater produces more of a frost-free environment for tender plants or seedlings.

The tube heater will not increase your utility bill; it may actually reduce it as it only consumes 135W of power. That is not much electricity compared to some electric heaters. It’s probably the cheapest greenhouse heater to run we have seen. However, this is mainly because it does not generate lots of instant heat like a fan style heater.

This heater is splash resistant, so the occasional splash of water from your greenhouse irrigation system that lands on the tube will not damage the unit. However it is not water proof so be careful not to place it under a water system or water over it. Ensure you position it somewhere dry.

You can decide where to place this heater as you can mount it on the wall or leave the unit free standing. It has stable feet to make certain that the unit stays where it should. If you decide to put it on the greenhouse wall, you can use the screws provided or suspend it from the roof.

PROS

  • Electric greenhouse heater that’s wall-mountable to keep it out of the way.
  • Very cheap to run and available in 3 different lengths.
  • Great for using to keep the frost out of your greenhouse.
  • Reasonably priced.
  • Splash resistant.

CONS

  • Cannot cater to plants that need higher heat levels.
  • No thermostat to control the amount of heat discharged.

Final conclusion

The LightHouse Eco Heat Greenhouse Heater is perfect for using more as a frost protection heater to keep the temperature a little above freezing, perfect for tender plants and seedlings in the winter

The unit is eco-friendly as it produces no offensive emissions. In addition, it doesn’t consume large amounts of electricity. In fact, it’s probably the cheapest model to run that we have seen.

The price varies with the length of heater you select. Choose the one that’s best for your size greenhouse or buy a combination of lengths to heat whatever growing area you have. You are constrained by the lack of thermostat to whatever heat the heater emits, and that’s why we suggest using this as a heater to keep the frost away from your plants.

If you’re looking for an affordable way to keep your greenhouse plants from freezing in the winter, and want a heating system you can build on, the LightHouse Eco Heat Greenhouse Heater is a great choice.


4. CrazyGadget Large Paraffin Super Warm Heater Single Burner

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The CrazyGadget Single Burner Large Paraffin Super Warm Heater uses paraffin to burn to generate heat. If you have an access as to where you can fetch cheap fuel, this unit will be of utmost help and is worth considering. The unit has a capacity of 5 litres which is fairly large and will give plenty of time before needing refilling.

The CrazyGadget Single Burner Large Paraffin Super Warm Heater is a single chimney heater uses paraffin as the fuel to generate heat. If paraffin is your fuel of choice for other garden appliances, you know how energy efficient it is as long as you have access to a cheap source of the fuel. This heater has a tank that holds 5L of paraffin which gives you around 80 hours of heating time.

Burning the paraffin as a fuel source does create emissions that are considered environmentally unfriendly. However, one of them is carbon dioxide, and plants love this as it helps with photosynthesis. Water is also a by-product of burning paraffin so that helps to keep your greenhouse environment moist and at a good humidity.

There are some considerations to be aware of with a paraffin greenhouse heater. It’s important to adjust the wick to the right length as this is the only way you have of controlling the amount of heat that the heater produces. In addition, always keep the wick trimmed as if it’s too long, it may deposit a black residue over your greenhouse. A paraffin heater is best for keeping the frost out of the growing environment rather than raising the air temperature to a certain level. Plus, of course, there’s always the fact that any open flame is a fire hazard, but these heaters are designed to be safe. Just don’t let kids and pets into the greenhouse when the heater is on, and take care yourself.

On a plus note, this is a heater that you can easily move from space to space and between greenhouses if you need to. You don’t have to worry about finding an electric outlet or heaving large propane tanks around.

The recommended dimensions for proper coverage by this paraffin heater is for a 1.8 by 1.8m greenhouse. Any space larger than that renders the unit inefficient and needs either two heaters of this size or one larger model.

PROS

  • Paraffin single chimney heater keeps the frost away when overwintering your plants.
  • Large capacity, thus will run for longer (average 2-3 days).
  • Portable design, no power cables to worry about.
  • The carbon dioxide and water vapour emissions provide stable growth.
  • Affordable price.

CONS

  • Can be expensive to run if fuel is expensive.
  • Has to be turned off manually.
  • No thermostat.

Final conclusion

The CrazyGadget Large Paraffin Super Warm Heater Single Burner is a large unit compared to some other paraffin models we looked at during our research. We specially like the large 5 litre capacity because it can run for around 80 hours without refilling which gives you around three days of consistent heating.

The price of this unit is at the lower end of our price range as long, and is inexpensive to run as long as you have an affordable source for the paraffin fuel. You have to physically turn the unit off and on and you shouldn’t leave it completely unattended without checking in on it occasionally.

If you’re OK with using paraffin as a fuel source and have ready access to an inexpensive supply, the CrazyGadget Large Paraffin Super Warm Heater Single Burner is a handy greenhouse heater to have.


5. Biogreen WM-P5 Warmax Power5 Paraffin Heater

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Biogreen WM-P5 Warmax Power5 Paraffin Heater

The Biogreen WM-P5 Warmax Power Paraffin Heater is a twin chimney heater for your greenhouse. The 4.5L tank holds enough paraffin to run for 16 hours. This may seem strange as our previous paraffin heater, the CrazyGadget Single Burner, runs for a full 80 hours on just a little more paraffin, 5L. However, the second chimney of this Biogreen heater lets you put out twice the hot air, if you want, but does take more fuel to do so.

The twin chimneys distributed the hot air over a wider area. This model heats up to 5 m² of greenhouse area (at a regular height). The unit is made of stainless steel which makes it rust proof (useful in the humidity of a greenhouse) and durable. As with any other paraffin heater, the by-products of carbon dioxide and water vapour help to create a healthy climate for your plants to flourish in.

You do need to turn the heater on and off manually though. There isn’t a thermometer to monitor the air temperature so you’re on your own to decide when to do that. This is a floor-standing heater, but it does come with brackets to anchor it firmly to the floor so you don’t accidentally trip over it and upset it.

PROS

  • Paraffin as fuel, great if you don’t have an electricity supply nearby.
  • Portable, no electric supply needed.
  • Twin burners for extra heat.
  • Inexpensive to run as long as you get paraffin at a good price.
  • Lightweight durable construction.
  • Can be bolted to the floor.

CONS

  • Soot produced if you don’t maintain the wick correctly.
  • No options for timers or thermostat.

Final conclusion

The Biogreen WM-P5 Warmax Power5 Paraffin Heater is a heater with twin chimneys for double the heat output. Or run with just one chimney on milder days. You can decide to switch both of the heaters on or decide to have one running. We do like that the unit can be bolted to the floor to make sure that there are no accidental spills.

This is a good heater if you don’t have an electricity supply near your greenhouse and want a heater with a choice of heat outputs. Admittedly your choice of actual heat temperatures relies on adjusting the wick, but at least it’s something.


6. Eden 2Kw Gas Greenhouse Heater

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Eden Gas Greenhouse Heater 2kW

The Eden 2KW Gas Greenhouse Heater uses propane gas for maximum performance. The heater has a valve that you attach a propane source such as a standard gas bottle, readily available at garden centres, petrol stations and local DIY stores.

The 2KW heater is very effective. It comes with a controllable thermostat that lets you change the temperature with a numbered dial similar to that of a thermostat on a radiator. You don’t get a precise temperature but you can manoeuver it from high to low heat through the pre-set numbers provided.

The unit is well made and can stand comfortably on its own. It cannot be mounted since no brackets are provided which is a shame. The unit is lightweight and that means you can move it easily from place to place.

The unit is designed with an oxygen depletion system. This makes certain that the carbon dioxide levels are high enough to support the plants as they grow. Propane heaters produce carbon dioxide as much as the paraffin heaters. This is why these heaters are popular when raising seedlings in a greenhouse setting.

The dimensions of the unit are 30cm (width), 13cm (depth) and 48 cm (height).

PROS

  • Propane heater is standalone and lightweight, so it’s easily moveable about the space and into different greenhouses.
  • Efficiently keeps the greenhouse at a consistent temperature.
  • Inexpensive to run if you shop around for the best gas prices.
  • Emits carbon dioxide as a by-product that’s beneficial for plants.
  • Contains a safety valve and piezo ignition for reliability.

CONS

  • Temperature control is not very precise.
  • Hose pipe is a little short.

Final conclusion

The Eden Gas Greenhouse Heater offers excellent value for money when you take into consideration the features provided. The unit runs on propane gas which can be expensive in some areas, so it’s worth checking prices first. The unit is of a simple construction and emits heat from the top.

The unit provides 2KW of output which is about right for most small greenhouses. Since the unit is well built, you can expect many years of service from it if you look after it well, including having it regularly serviced.

If you like gas appliances and have a small to medium greenhouse, the Eden 2KW Gas Greenhouse Heater is a sturdy and safe choice.


Biogreen PHX 2.8/GB Phoenix Electric Fan Heater 1.0/ 1.8 /2.8KW

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Biogreen PHX 2.8/GB Phoenix Electric Fan Heater 1.0/ 1.8 /2.8KW

The Biogreen PHX 2.8/GB Phoenix Electric Fan Heater is a slightly larger model than our Best Pick, the Bio Green PAL 2.0/GB 2KW Palma Heater, and has the thermostat built in. This is handy for you to select the temperature you want the greenhouse inside air to be at. You have a choice of three power levels to run this heater at: 1KW, 1.8KW and 2.8KW (which is the result of running the first two heating parts together).

This Biogreen PHX 2.8/GB model has many of the same structural features as the Best Pick. It’s made of stainless steel, a rustproof metal which is handy in the damp environment of a greenhouse. Stainless steel is also durable and lasts many years. The heater itself is spray proof and can withstand the occasional spraylet of water from your irrigation system or watering can; it cannot stand up a deluge though. You can use the heating part with the fan or the fan alone to circulate and cool the air and to slow down any mould or fungus growth.

You have a choice of a temperature adjustment range of 0°C and 26°C with this heater. That’s enough of a range to produce hardy young seedlings and to facilitate the growth of strong and healthy mature plants. However, unlike the precision of the thermostat in our Best Pick, this model’s temperature control is reported by online reviewers to be within 4°C or so of the requested temperature.

PROS

  • Electric greenhouse fan with choice of three heating powers.
  • Heating and cooling settings on the fan allow you to use this heat to just move the air around for better ventilation.
  • Floor mounted safely with brackets or roof mounted with (included) hanging chains so fits into any greenhouse set up.
  • Spray proof and comes with the IPX4 certification to prove it.
  • Stainless steel for rust-proof operation and durability in a moist environment.
  • Heats a growing space up to 9.3m2 so make sure you’re using your space efficiently.
  • Frost protection in a space of up to 16.7m2, so you can overwinter large and fully grown plants.
  • Temperature range between 0°C and 26°C suits both young seedlings and fully grown plans.

CONS

  • Thermostat is not as accurate as a digital one.

Final conclusion

The Biogreen PHX 2.8/GB Phoenix Electric Fan Heater is a powerful electric greenhouse heater that offers you a choice of heating outputs. Choose for whatever your plants need at the time or for how quickly you want to heat the greenhouse air. Your choice of temperature adjustments is in a range that’s suitable for all stages of most domestic plant’s lives, though the thermostat is not very precise. Instead of opening the roof vent on a hot day, use the heater’s fan to circulate the air and cool down the greenhouse interior.

If you have a larger greenhouse and want to grow plants with changing temperature needs, the Biogreen PHX 2.8/GB Phoenix Electric Fan Heater is worth considering.


Buyers Guide

Buying a heater for your greenhouse is not quite as simple as it first seems. It’s not that the heaters themselves are complicated, it’s that you need to put quite a lot of thought, planning and even some basic maths into your decision. But don’t worry, this Buyer’s Guide explains the basics of all of this.

Size

Let’s get the maths over with right at the start. Conveniently, the specifications of most heaters tell you what floor area (in m2 or ft2) they can efficiently heat. These measurements assume a standard height greenhouse as the space inside is really in m3 or ft3. You just have to measure your greenhouse floor dimensions and work out the area.

If your greenhouse area is larger than your intended heater can handle, you have several choices: move up to a larger heater; buy two or more of your chosen heaters; or insulate your greenhouse if you have not done so already. On the other hand, if your chosen heater puts out too much hot air for your growing space, select a smaller heater. You don’t want your plants to be too hot or to have to keep your roof vent or door open when the heater’s on – that’s just wasting electricity/gas/paraffin.

How to heat a greenhouse and everything you need to know

So, the obvious question is, how do you know how much heat your plants need? What temperature should you keep the inside of the greenhouse at? Well, that’s where your/your neighbours horticultural knowledge/reference books come in or a google search.

Plus knowledge of how hot it gets inside your greenhouse at different times of the year. Plus investment in a really good thermometer. Plus your plans for what to grow when. Are you going to be starting your seeds in early spring? Are you going to be overwintering your plants. Are you growing orchids and other exotic hothouse plants? Please spend time on these considerations as they really determine the type and size of heater that’s best for your growing plans.

Power Source

You have three different kinds of power source for your greenhouse heater. Your choice may come down to personal preference, the availability of any one of these or the cost.

Paraffin

The more traditional heaters use paraffin as a fuel source. They don’t need much maintenance. While they do produce some emissions as by-products of burning the fuel, two of them are carbon dioxide and water. These by-products are beneficial to plants and help to create a healthy environment inside the greenhouse.

CrazyGadget Large Paraffin Super Warm Greenhouse Heater

Paraffin heaters don’t allow you to regulate the temperature much. They’re best suited for keeping the frost out of the greenhouse in autumn, winter and early spring rather than regulating the temperature to a particular degree. They don’t have built-in thermostats or thermometers and you have to manually turn them on and off. The heater will continue running by itself until it runs out of fuel.

While the water produced adds wonderfully to the humidity in the greenhouse, too much moisture encourages mould, so watch out for that. In some places, paraffin fuel is expensive, more so than electricity of propane gas. This might affect your purchasing decision.

Paraffin heaters are useful if your greenhouse is out of the way, without access to the electric grid.

Electricity

Electric heaters are the easiest to use as long as you have a power outlet to plug them in. The best ones have an inbuilt thermostat which you set to the required temperature. The heaters switch themselves on until that temperature is reached and then turn themselves on. When the temperature drops a set amount, back on comes the heater, just like the central heating in your home.   The not-so-top-of-the-line electric heaters may have just a couple of power settings that you choose and they run at that setting.

heating greenhouse with electric heater

Putting an electric appliance in an environment which, at the least, is humid and at the most has a running irrigation system can be risky. Look for heaters that are splash-proof. A certification of IPX4 or IPX6 (even better) is necessary for your safety.

Heaters with fans make your life and greenhouse environment easier. Fans remove excessive water from the air as they circulate the warm air. You can even run the fans without the heating element being on if you want to cool the greenhouse air.

Some electric fans are freestanding and others can be mounted on the wall to keep then out of the way. Of course, as with any electric appliance, you can hook a timer up to your electric heater, if you have a schedule on which you heat your greenhouse, in the evening for example.

Propane

Propane heaters use the familiar and readily available propane gas bottles as their fuel source. Just like paraffin based heaters, propane units produce a great deal of carbon dioxide which is important in the photosynthetic process. The only drawback is the moisture produced, which may create too much humidity if left unattended.

Eden Gas Greenhouse Heater Review
Eden Gas Greenhouse Heater

Keep track of how long you’ve used the gas bottle for and how much running time the manufacturer says each bottle gives. The difficulty with propane greenhouse heaters is finding models with thermostats; we found just one gas model that we would recommend.

Most units measure the output in kilowatts (KW) The higher the KW, the more heat is output and the more space can be heated. Most basic models range from 1KW to 3KW.

Insulating your greenhouse

We just want to briefly encourage you to insulate your greenhouse to save on your heating costs. One way is to pin bubble wrap to the walls. The air in the bubbles provides an efficient and low-cost insulating layer to the air inside the greenhouse. We have a step-by-step guide to doing this. We also review the four best materials for insulating your greenhouse. These materials include the above-mentioned bubble wrap and also fleece.

Learn how to heat a greenhouse without electricity or keep it frost free we have some tips from better insulating your greenhouse to other heater alternatives to electric

Safety

Putting any kind of heater inside an environment designed to have moist, humid air, a working irrigation system and organic matter needs some safety considerations. Please read carefully the safety instructions that come with any heater and any other garden appliance you have in the greenhouse. Keep out kids and pets and be careful when you’re pottering around in there yourself.

FAQ

Do I need to be near an electric outlet to have a greenhouse heater?

No. The greenhouse heaters we review here are powered by either paraffin, gas or electricity. Each of these methods has its own advantages and drawbacks. Electricity is clean and cheap, but you do need to be by an outlet. Paraffin is the traditional method of heating, gives your plants beneficial carbon dioxide but can be expensive. Propane gas is readily available and relatively inexpensive but may produce too much water in the air. See our Buyer’s Guide for this information.

How do I know how much to heat my greenhouse?

Your greenhouse’s inside temperature should be suitable for the plants you want to grow there.

The natural inside temperature depends on:

  • How many windows and doors there are and where they’re sited (Does warm air rush out or cold air rush in when they’re opened?)
  • Where the greenhouse is sited (North, south etc) and how much sun it gets
  • The time of the year
  • How insulated is your greenhouse (What is the glazing made of? Is there additional insulation?)

You need to calculate the difference between the outside temperature and the inside temperature of your greenhouse and heat or cool it so that it’s the temperature your plants need.


Our Final Conclusion

Finding a good heater for your greenhouse may seem like a complicate process. What you need to remember is that the size of your greenhouse will determine the amount of power that you use. It is better if you find those that produce carbon dioxide since it will benefit your plants. The amount of power you use will affect your monthly bill so choose wisely.

An easy to maintain unit will always be of benefit to you. Having a thermostat allows you to have more control over the temperature in your greenhouse climate.

Below is a quick roundup of some of our favourite greenhouse heaters:

Best Pick

Bio Green PAL 2.0/GB 2KW Palma Heater with Digital Thermostat

Bio Green PAL 2.0/GB 2KW Palma Heater with Digital Thermostat

We looked at the products presented and we analysed the pros and cons of each greenhouse heater. After careful consultation, we chose the Bio Green PAL 2.0/GB 2KW electric Palma Heater as the best greenhouse heater for most gardeners.

The 2kw model can warm up small places pretty quickly. The warm air is distributed evenly and fast.  It has precise temperature controls and a wide range of temperature adjustment selections. It is not that expensive to run since it has a thermostat that switches it off once optimum temperature are reached.

Overall an excellent greenhouse heater and one that is also affordable to run.


Best Paraffin Heater

The CrazyGadget Single Burner Large Paraffin Super Warm Heater uses paraffin to burn to generate heat. If you have an access as to where you can fetch cheap fuel, this unit will be of utmost help and is worth considering. The unit has a capacity of 5 litres which is fairly large and will give plenty of time before needing refilling.

For our paraffin heater choice, our recommendation is that the CrazyGadget Large Paraffin Super Warm Heater is the best. This is because the unit will run for up to 80 hours without requiring a refill. The large unit can supply enough heat and carbon dioxide to make certain that your plants grow healthy.

If you have a cheap source of paraffin, then this unit will be inexpensive to run. If not, you may incur large bills, especially if you have several units running inside a larger greenhouse. Remember to put moisture control mechanisms in your greenhouse to adjust the moisture levels to reduce the growth of mould and fungus.

Best Gas Greenhouse Heater

Eden Gas Greenhouse Heater 2kW

Eden Gas Greenhouse Heater 2kW

This is the only gas greenhouse heater that we included in our review. This propane gas model works the same as a paraffin heater by producing carbon dioxide as part of its emissions. This promotes plant health, especially for seedlings. The unit has only one port to dispense the heat through. But it is splash resistant. Propane gas is usually relatively inexpensive and widely available at gas stations and camping stores.


Other product reviews you may also be interested in (Links will open in new window)

We review the best heated propagators and compare the features to see which would be the best choice for you

How to insulate your greenhouse

Read our reviews of the best automatic greenhouse vent openers

Best mini greenhouses for small gardens


Last update on 2021-10-15 / Affiliate links / Images from Amazon Product Advertising API

Welcome to my site, my name is John and I have been lucky enough to work in horticultural nurseries for over 15 years in the UK. As the founder and editor as well as researcher, I have a City & Guilds Horticultural Qualifications which I proudly display on our About us page. I now work full time on this website where I review the very best gardening products and tools and write reliable gardening guides. Behind this site is an actual real person who has worked and has experience with the types of products we review as well as years of knowledge on the topics we cover from actual experience. You can reach out to me at john@pyracantha.co.uk

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