Best for
Owners of a 6x8 to 8x12 greenhouse who need frost protection or a modest overnight hold on a single GFCI-protected 120 V circuit.
#16 in the buying orderHeatingBuy when needed
Bio Green Palma 1500W Greenhouse Heater
The default heater for a 6x8 to 8x12 twin-wall greenhouse: 5,120 BTU, a real thermostat, IPX4 splash protection and a two-year warranty on a standard outlet.
- Current price
- $149.99 at biogreen-products.com
- Checked September 20, 2026
- Review type
- Independent desk review
- Not a physical product test
Skip if
Your heat-loss math needs more than about 5,000 BTU per hour, you have single glass in a cold climate, or you cannot give it a GFCI-protected outlet of its own.
Hidden cost
About 27.5 cents per hour at full duty at the June 2026 US residential rate of 18.34 cents per kWh, plus a GFCI outlet if the greenhouse does not have one.
Why it made the list
The buyer case
Bio Green sells it as a greenhouse heater, not a household one: switchable 750 or 1500 W, a manual thermostat, IPX4 splash protection and a two-year replacement warranty, in stock on September 20, 2026.
Compatibility comes first
110 V, one heater per outlet. Bio Green rates it for rooms up to 130 square feet; by extension-service heat-loss math it covers a 6x8 twin-wall house at a 30 degree gap with margin and an 8x12 without one.
Installation boundary
Set it low on the floor, aimed along the length of the house, away from drip lines and the watering path. Put a remote thermometer at plant height on the far end to confirm the heat arrives.
Our verdict
The right first heater for a small polycarbonate house. Size it with the heater guide first; if the number comes out over 5,000 BTU, buy the Phoenix or a 240 V unit instead of a second Palma on the same circuit.
Primary sources
Product facts come from these direct sources. They are kept separate from the purchase button, and none is rewritten through an affiliate redirect.
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Canopia Portable Greenhouse Fan Heater 1500W NA
Check a current US distributor
A purpose-built 1500W fan heater is a better fit than an exposed household space heater, but the greenhouse heat-loss math still decides whether it is enough.
- Best for
- Small North American greenhouses needing frost protection on a correctly sized circuit.
- Skip if
- Your heat-loss calculation exceeds the output, the greenhouse has no safe GFCI-protected supply, or you expect a 1500W heater to hold warm-growing temperatures through severe cold.
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Bootstrap Farmer 24V Greenhouse Thermostat
$115.99
This is a proper 24V climate-system thermostat, not a universal plug-in controller for any heater or fan.
- Best for
- A greenhouse heating or cooling system designed for 24V thermostat control.
- Skip if
- You are trying to plug a normal 120V appliance directly into it. That is not what this thermostat is for.
#17Buy when neededHeating
Bio Green Phoenix 2800W Greenhouse Heater
$299.99 at biogreen-products.com, down from $329.99
The step up when one 1500 W heater is not enough: 9,554 BTU on a 240 V circuit, with a thermostat that runs from minus 58 to 79 degrees F.
- Best for
- A 10x12 or 12x16 twin-wall greenhouse, or a smaller single-glass house, where the heat-loss number lands between 5,000 and 9,500 BTU per hour.
- Skip if
- You do not have, and will not install, a 240 V circuit in the greenhouse. On 120 V this heater does not exist as an option.