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About Our Greenhouse Heaters
A heater turns a summer greenhouse into a year-round one. Hold it just above freezing and you can overwinter geraniums, fuchsias and citrus; push it to 10°C and you can sow weeks before anyone with an unheated house. We stock electric, gas and paraffin heaters from Eden, Palram Canopia and Elite, from £145.
Two things decide which heater you need: the size of the greenhouse and whether you have power to it. A 2kW electric heater holds frost off a 6x4 or 8x6. Larger or glass-to-ground houses lose heat faster and need 3kW or a gas heater. No mains supply? Gas or paraffin run independently, though they add moisture you must vent.
Why We Chose This Range
"People ask me which heater is cheapest to run, and the honest answer is the one with the best thermostat, whatever the fuel. I have watched a cheap heater with a crude dial burn money holding a greenhouse far warmer than it needed. Electric with a proper thermostat is the cleanest for most people. I keep gas and paraffin for plots with no power, but you have to crack a vent because they put water into the air as they burn."
— Matt, Founder of Greenhouse Stores💡 Tip: Heat a smaller space, not the whole greenhouse. Curtaining off one end with bubble insulation, or standing tender plants together under fleece, lets a 2kW heater do the work of a much bigger one.
🔧 Expert Tip: Get electric power in safely
A greenhouse is a wet place full of metal, so electric heating needs an outdoor-rated supply on an RCD, ideally a proper armoured cable run by an electrician, not an extension lead trailed across the lawn. Stand the heater clear of foliage and let it draw and blow air freely.
Matt, Greenhouse Stores Co-Founder
Matt's Pick: Palram Canopia 2400W with thermostat
Best For: A mains-powered 6x4 to 8x6 that needs reliable frost protection.
Why I Recommend It: The built-in thermostat is the bit that saves you money. It holds your set temperature and switches off the moment it is reached, so you are not paying to overheat.
Price: from £199
Greenhouse heater fuels compared
| Fuel | Best for | Watch out for |
|---|---|---|
| Electric ⭐ Matt's Pick | Clean, thermostatic, set and forget | Needs a safe mains supply |
| Gas / propane | Powerful heat, no mains needed | Adds moisture, must be vented |
| Paraffin | Cheap backup, frost protection | No thermostat, adds damp |
Frequently Asked Questions
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What size greenhouse heater do I need?
A 2kW heater suits a 6x4 or 8x6. Larger, timber, or glass-to-ground greenhouses lose heat faster and need 3kW or more. Match the heater to the space, then set the thermostat to the temperature you actually need.
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Is electric or paraffin cheaper to run?
It depends on control, not just fuel. Paraffin is cheap to buy but has no thermostat, so it burns constantly. Electric with a good thermostat only runs when needed, which often makes it cheaper overall and far easier to manage.
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What temperature should I keep my greenhouse?
Aim for 3 to 5°C to keep frost off most tender plants. Raise it to around 10°C if you want to start seeds early or grow on through winter. Every degree higher adds running cost, so heat only as much as the plants need.
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Do gas and paraffin heaters need ventilation?
Yes, always crack a vent with gas or paraffin. Both give off water vapour as they burn, which raises humidity and can encourage disease. A little ventilation clears the moisture while still holding useful heat.
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Do I need to heat my greenhouse in winter?
Only if you grow tender plants or sow early. An unheated greenhouse still keeps off the worst frost. A heater matters if you overwinter pelargoniums, citrus and similar, or want a head start in spring.