In this guide we’ll look at the best greenhouse heaters for the UK market.
I’ve compared performance, size, build quality and cost
to give you my top recommendations.
What Is The Best Greenhouse Heater?
In a rush? Here’s my top choice…
Powerful greenhouse heater with excellent digital thermostat!
This Bio Green PAL 2.0/GB 2KW Palma Heater is a powerful electric heater which is economical to run. It will keep your plants happy by keeping your greenhouse warm, with a digital thermostat that can be set up to 99°C. It’s splash-proof, so can be used in damp conditions, and works effectively in spaces up to 12 m².
Things to Know Before Buying a Greenhouse Heater
Ah, greenhouses! Also known, in the UK, as ‘our best bet for keeping plants alive that are used to warmer climates’. In the summer they are extremely effective. However, during a UK winter sometimes even a greenhouse isn’t enough to keep plants content.
Using a greenhouse heater will not only help keep your plants healthy, it will also help protect the structure of the greenhouse. If there is too much static moisture in a greenhouse, mildew and mould can grow. This might affect the greenhouse itself just as much as the plants.
A greenhouse heater will maintain a good temperature and keep air circulating around the greenhouse, as well as protect the environment from unwanted damp.
As you can see, these heaters can be invaluable when it comes to looking after your garden over the winter; but how can you make sure you’re buying the best greenhouse heater?
Well, look no further! I’ve put together the following information so that you can be sure you’re making an informed purchase:
The heating output from a greenhouse heater varies from model to model. How much heat you’ll need also depends on what you’re hoping to achieve with your heater.
The following shows roughly how much power your heater will need to heat various size greenhouses:
1 kW – Heat greenhouse of 14.6 m²
2 kW – Heat greenhouse of 18 m²
3 kW – Heat greenhouse of 36.5 m²
4 kW – Heat greenhouse of 45.7 m²
6 kW – Heat greenhouse of 70 m²
And the following information shows roughly how much power your heater will need to offer frost protection in various size greenhouses:
1 kW – Frost protection in greenhouse of 24 m²
2 kW – Frost protection in greenhouse of 36.5 m²
3 kW – Frost protection in greenhouse of 79 m²
4 kW – Frost protection in greenhouse of106.7 m²
6 kW – Frost protection in greenhouse of 152.4 m²
The majority of electric heaters have a variety of heating settings and a thermostat so you can adjust them according to your needs. Some gas heaters also offer a range of heat settings, depending on the model.
Most greenhouse heaters are designed to be as energy-efficient as possible. By nature, electric heaters are known to be ‘100% energy efficient’ because they convert all power into heat – but that doesn’t necessarily mean they’re the cheapest to run.
Gas heating in a greenhouse it generally considered to be the cheapest option, and they run at around 80% efficiency. Using a gas heater can keep costs down because you know exactly how much fuel you have put in the heater before it starts heating. Therefore, it’s a little bit like one of those pay-as-you-go electricity meters – you’ll be aware of all running costs up front.
As mentioned, an electric heater is 100% energy efficient. They don’t produce fumes, as gas heaters do, and therefore don’t require any ventilation in the greenhouse which leads to heat escaping. However, it may be very costly to leave an electric heater on for days on end.
The cost of running an electric heater depends on the kW setting of the heater. If you pay your electricity company 0.14p per kWh (this is roughly the UK average, but you should check your specific rate) then it will cost 0.14p to run a 1 kW heater for an hour. Therefore, it will cost approximately 0.42p to run a 3 kW heater for an hour. And if you run a 3 kW heater for 8 hours… well, you’re looking at a running cost of £3.36 for that time period.
As a result, you should look carefully at the power of the heater you’re thinking to buy. Make sure you don’t buy an unnecessarily powerful heater, look for adjustable settings, and work out how long you can realistically afford to keep it running for (and if that will actually serve your desired purpose or not).
As mentioned above, under ‘Running Costs’, gas heaters can be cheaper to run than electric ones. However, there are other pros and cons to both electric and gas powered heaters which are worth knowing.
The fact that gas heaters are generally low cost to run tends to be their biggest selling point.
The one other main factor working in their favour is that they don’t require a power outlet. So if you don’t have a way to connect electricity in your greenhouse, a gas heater is probably going to be your best option.
There are also a few problems that can arise from using a gas heater. Open flame heaters can emit fumes which will likely cause damage to plants, especially blossoming ones. They may fail to blossom at all.
You will generally have to create an ‘exhaust hole’ in your greenhouse if you choose to use a gas heater. This will make sure that it doesn’t cut out if it’s not got enough oxygen (greenhouses can be so well insulated that they are almost air-tight, so there may not be enough oxygen to keep a gas heater running with the doors closed for hours). If the heater were to cut out overnight, it could spell disaster for your plants.
So, when looking at running costs, we’ve seen that these electric heaters could become expensive to run.
They also require you to have a power outlet in or near your greenhouse. This might be fine for some gardeners, but impossible for others. No electric socket, no electric heater.
However, on the plus side, electric heaters don’t release any fumes which might be damaging to plants, and will continue to run regardless of the oxygen levels in the greenhouse.
The best greenhouse heater will be a convection heater: one that warms the air in the greenhouse, not just transferring warmth through radiation.
A thermostat is a very handy feature on a greenhouse heater as it will ensure that the area remains at your preferred temperature all the time. In addition, a thermostat ensures you don’t waste energy heating your greenhouse to a higher temperature than you need.
Everything We Recommend
More Detailed Greenhouse Heater Reviews
Bio Green PAL 2.0/GB 2KW Palma Heater with Digital Thermostat Review
The Bio Green PAL 2.0/GB 2KW Palma Heater is the best electric greenhouse heater on the market. It’s powerful, economical and comes with a digital thermostat!
This electric greenhouse heater is compact and durable, featuring an IPX4 rating which means it’s splash-proof – ideal for damp greenhouses!
The build quality is excellent, with a stainless steel construction, and the unit looks great too!
The heater features a handy carry handle so it is easy to move around. Plus, the decent 190 cm cable makes it easy to position in the right place.
This heater has a separate digital thermostat which can be set to temperatures from -50°C to +99°C. This makes it easy to maintain the perfect temperatures for your plants.
The 2 kW motor is effective at powering the fan, providing an air circulation rate of 163 m³/h. This means it creates an even temperature throughout the greenhouse with no hot or cold spots.
Good air circulation is also vital to prevent mould, mildew and fungal diseases.
The heater is suitable for greenhouses and other spaces up to roughly 12 m².
Overall, this is an effective and simple to use heater that you can just set up and leave to protect your plants over the winter. It is light and easy to carry, making it the an excellent portable greenhouse heater; hassle-free to move around as required.
2kw Electric Greenhouse Heater Review
This 2KW Electric Greenhouse Heater is robust and reliable, offering good value for money considering all of its features.
It has a useful thermostat that will allow you to protect your greenhouse plants with no fuss. You can rest assured knowing that it will maintain your desired temperature.
The handy carry handle makes it easy to move around depending on which plants need to be closer to the heat source or further away.
With a 3-speed fan that runs continuously to increase air circulation, you can choose how much power you want the heater to be using at any given time. The fan provides air circulation at a rate of 186 m³/hr which keeps your plants healthy and prevents the growth of mould and mildew.
This reliable and sturdy greenhouse heater offers excellent build quality and range of features, making it incredible value for money. It’s the best small greenhouse heater in this price range – I strongly recommend!
Biogreen WM-P5 Warmax Power5 Paraffin Heater Review
The Biogreen WM-P5 Warmax Power5 Paraffin Heater is the best paraffin greenhouse heater on the market, offering a simple yet effective way to keep your greenhouse frost free without the need to connect to mains power!
This heater is simple to use. You simply insert the wick, fill the canister with paraffin, and light it. It is important to trim the wick quite low to prevent smoking.
This tiny little heater will keep the average 2.5 x 2 m greenhouse frost-free in the harshest weather conditions.
It has a traditional design, is reasonably priced and super cost-effective. 4 L of paraffin is enough to keep it alight night and day for a week!
Overall, this is a simple product that keeps your greenhouse frost-free and is ideal for use if you have no access to mains power in your garden.
Dimplex ECOT1FT Tubular Heater Review
The Dimplex ECOT1FT Tubular Heater is compact, effective and well designed.
It is easily mounted onto brackets, keeping it out the way and allowing you to benefit from more floor space in your greenhouse. The mounting brackets and full instructions are included.
This heater is IPX4 rated, making it splash-proof and safe for use in greenhouse conditions.
It has a low wattage of 40 W so is safe and cheap to run, yet will still provide a frost-free environment for your plants!
The thermostat is easy to set and super accurate; you can maintain just the temperature you need which your plants will undoubtedly thank you for!
The heater comes with a 1.5-metre cable and a 3 pin plug.
It offers a safe, cost-effective option for keeping your greenhouse frost-free this winter!
Bright Spark Portable Gas Heater Review
The Bright Spark Portable Gas Heater is a convenient and cost-effective unit that offers instant heat for the greenhouse!
This light and portable heater has a handy carry handle so can easily be moved wherever it is needed. Despite its lightness, the steel construction feels durable and long-lasting.
The heater provides instant heat and is fuelled by a butane canister. It features piezo automatic ignition for easy lighting, so you won’t have to waste time trying to turn it on.
Each butane canister will give you up to 3 hours on full heat, and you’ll get even longer from it on lower heat settings; the heater also has an easy-to-use temperature control dial.
The Bright Spark Portable Gas Heater is a great low-cost solution to heating your greenhouse during periods of very cold weather. As a portable gas heater, it’s really handy if you have no mains power in your greenhouse!
Greenhouse Heater FAQs
The size of heater required will depend on the size of your greenhouse, the material it is made from, and any insulation you have fitted. It will also depend on the temperature you want your greenhouse to be.
As a rough guide, the information below will show the power you need for different size greenhouses:
1 kW – Heat greenhouse of 14.6 m². Frost protection in greenhouse of 24 m².
2 kW – Heat greenhouse of 18 m². Frost protection in greenhouse of 36.5 m².
3 kW – Heat greenhouse of 36.5 m². Frost protection in greenhouse of 79 m².
4 kW – Heat greenhouse of 45.7 m². Frost protection in greenhouse of106.7 m².
6 kW – Heat greenhouse of 70 m². Frost protection in greenhouse of 152.4 m².
This will depend on the size of your greenhouse, your access to mains electricity and the specific conditions your plants require.
If you have mains electricity, then an electric fan heater with a thermostat will be your best choice. This will ensure you can maintain your greenhouse at the right temperature over winter and increase air circulation to prevent mould, mildew and fungal diseases.
If you don’t have access to mains electricity, a gas-powered heater will be the way to go.
There are a lot of tactics for keeping your greenhouse warm over winter, with or without using electricity.
A greenhouse heater is a sure-fire way to keep your greenhouse warm and at a steady temperature. You could also move your composting facilities into the greenhouse – composting materials create heat. Wrapping up a small greenhouse with insulating material such as bubble wrap is another option, or you could section off part of the greenhouse with plastic to keep that smaller section warmer and more insulated.