Thanks to our infamous British climate, the growing season here in the UK is disappointingly short. One way to counter this is with a garden greenhouse. A greenhouse provides a sheltered place for your plants and, for most months of the year, offers a warmer environment than the open air. However, in the winter months, glass panes provide little protection against the chilly weather.
That's where a greenhouse heater can come in - a standalone device that can provide a source of essential warmth to stop the inside of your greenhouse from freezing over and protect your plants from the worst of the winter weather. Whether you're looking to further shield outdoor plants you're overwintering in your greenhouse or trying to bring on new growth, the best greenhouse heater can help your outdoor growing space reach its optimum temperature.
The best greenhouse heaters at a glance:
There are a wide range of greenhouse heaters on the market that are powered in a variety of ways. The three most popular greenhouse heater fuel types are electricity, gas, and paraffin. We have a selection of all these kinds in our roundup of the best greenhouse heaters currently available. Take a look at our top choices, and hopefully, you'll find a greenhouse heating solution to suit you…
Best greenhouse heaters
Best overall greenhouse heater
Bio Green A highly recommended product that currently enjoys a 4.4-star Amazon rating, Bio Green's 2KW heater is specially designed for use in greenhouses and can warm spaces up to 12 square metres. This model comes with a digital thermostat that automatically starts and stops the heater when the desired temperature is reached. The range is from zero to 60 degrees.
This heater boasts an air circulation mode that offers fan-style operation. Moving the air around prevents hot spots from building up around certain plants and stops mould formation. It has a sturdy stainless steel case, a foldable carrying handle, and is splash-proof to IPX4 levels.
Pros
- Has fan action which helps circulate the warm air
- IPX4 certification for splash-proof protection
Cons
- Reviewers report this heater is expensive to run
Best propane greenhouse heater
Edenwww.keengardener.co.uk
A propane greenhouse heater is a strong choice for anyone who has a greenhouse on an allotment or can't run electricity to the glass house in their garden. This greenhouse heater is powered by propane cylinders in a size that suits your space. It is designed for smaller spaces, with the manufacturer stating it can warm 5.5 square metres, but one reviewer reports success in using this to heat their six-foot by 10-foot greenhouse.
It has an integrated thermostat, so you can choose the temperature that suits the contents of your greenhouse. The possible temperature range starts at seven degrees and can reach a steady level of 32 degrees. This heater offers a piezo ignition, so it's quick and simple to get it burning.
Pros
- Boasts a narrow footprint to save space
- This is supplied complete with the necessary hose and regulator
Cons
- Thermostat is only accurate to plus or minus three degrees
Best infrared greenhouse heater
Donyer Power If you don't have the floor space for a greenhouse heater, a ceiling-mounted solution could be the best option for you. This heater suspends from a one-metre chain that's adjustable to suit the height level you require. Once installed, this heated lamp is controlled via a pull cord. With two different settings, you pull the cord down once to activate an 800W heating level, again for 2,000W and then pull it again to turn it off.
The beauty of halogen heaters is that the heat is near-instant. The other benefit is there is no noise, so you won't be troubled by the rattle of a heater while you're pottering around your greenhouse. This boasts an IP24 rating, meaning it can withstand the odd splash.
Pros
- Two different heating levels; 800W, and 2,000W
- This halogen heater warms up rapidly in a matter of seconds
Cons
- Not suitable for spaces with low roofs
Best electric greenhouse heater
Palram-Canopia www.keengardener.co.uk
Palram-Canopia is one of the UK's leading greenhouse manufacturers, so you'd expect them to know a thing or two about heating them. This is another electric option that offers thermostatic control and handy fan action to distribute the heat evenly. It can also be used as a non-heated fan in the warmer months of the year.
It boasts an IPX4-certified design for splash resistance, while the temperature sensor probe has earned IP65 certification. This contains a durable stainless steel heating element with an auto reset safety system and low-noise operation.
Pros
- Separate digital climate control unit to set the desired temperature
- Offers a 2,400W output ideal for larger greenhouses
Cons
- Not a particularly compact option
Best paraffin greenhouse heater
CrazyGadgetIf you're confident handling flammable liquids, a paraffin-powered greenhouse heater is an affordable option that's open to you. This large paraffin heater from CrazyGadget has a single chimney design, but it throws heat out on either side to warm your glass house space.
This heater is capable of warming a greenhouse measuring up to six by six foot. The large paraffin tank has a capacity of five litres which means it can burn for up to 80 hours from one fill. Reviewers advise sourcing a small funnel to top up the paraffin tank as one is not included.
Pros
- Paraffin is an affordable fuel type for small heaters
- Can throw out heat for up to 80 hours from one tank of fuel
Cons
- No integrated thermostat or thermometer
Best tubular greenhouse heater
Hylite This slimline solution is ideal for anyone who wants to opt for a space-saving, wall-mounted greenhouse heater. Although this heater has skinny dimensions, it boasts a full, dial-based thermostat control that can automatically adjust the temperature. This heater is sold in two sizes: a very compact 50cm option that could work for smaller potting sheds and a metre-long version that would be better for greenhouses.
It comes with a two-metre cable and plug, giving you flexibility as to where you position it, as well as with the fixings you'll need whether you lay this along the floor or opt for wall mounting.
Pros
- Consumes less electricity than traditional fan heaters
- Thermostat control that automatically adjusts the temperature
Cons
- No fan functionality for distribution of warm air
Best solar greenhouse heater
SirseonThis heater will never generate enough heat to nurture delicate seedlings, but if you position the solar panel in a place that receives a lot of sun, it could work as an eco-friendly way to create gentle background heat and prevent your plants from freezing. In addition to being environmentally friendly, this is also wallet-friendly, as there are no ongoing costs to incur.
This heater comes as a kit; you get the 30W heater, a dedicated battery unit, the solar panel, and all the cables you need to connect them up. The solar panel will easily sit on your greenhouse roof as it measures 20cm by 43.5. It's made of monocrystalline silicon and PET materials which means it can withstand harsh weather conditions.
Pros
- Tough and durable solar panel for year-round warmth
- This is a zero-cost solution once installed
Cons
- Not as powerful as electric, gas, or paraffin options
How we chose the best greenhouse heaters
All of these greenhouse heaters have been hand-selected by our team of Modern Gardens shopping experts. We carefully considered the fuel type, heat output, and effectiveness in our selection of the best. Our team has spent hours investigating and researching all types of greenhouse heaters to make it easier for you to find the very best, and we'd never recommend a product we don't believe in.
Where possible, we also test and share the latest and best products you should know about. And with help from Modern Gardens Magazine, Garden News and Garden Answers, we share expert gardening knowledge to help you get the most from your product.
Greenhouse heaters: Frequently asked questions
What's the best fuel type for a greenhouse heater?
We wish there were better solar solutions available, but the options at the moment are limited. If you have managed to set up an electrical connection to your greenhouse, we'd say using an electric heater is a no-brainer. The electric-powered greenhouse heaters currently available are designed specifically to warm a glass house, have useful thermostatic control, and offer safety cut-out functionality. The only downside is the cost of electricity, but you can try to control usage with the integrated thermostats.
Can I just run an extension lead to my greenhouse for an electric heater?
Nope. This is not a safe or sensible solution, even on a temporary basis. You need to have an electrical connection properly hardwired to your greenhouse, preferably installed by a professional.
How can I keep my greenhouse warm without using a heater?
The short answer is - you can't. The best you can do is try to protect against frost. Keep the glass clean so as much light filters in as possible. Use a transparent silicone filler on any cracks and around the glazing's frames to stop cold air from creeping in. A popular method to try and increase the temperature inside a greenhouse is to line the windows with bubble wrap. The downside of this is that you will lose around 10% of light emission. This shouldn't affect plants you're overwintering as they will pretty much be dormant anyway, but it could affect the development of younger plants you're cultivating. One 'hack' we can suggest is to create a greenhouse within a greenhouse' by placing a cold frame inside your greenhouse to double down on insulation.
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Amy-Mae Turner is a Commerce Content Writer for Modern Gardens, Yours, Take A Break Pets, and A Modern Kitchen. When she's not pottering in the garden or mucking around in the kitchen, she can be found having doggy cuddles with her two beloved cockapoochis.