The Bio Green Palma Greenhouse Heater is the best greenhouse heater for most backyard greenhouses: it was designed for greenhouses, holds temperature with a digital thermostat, has a splash-proof IPX4 rating and doubles as a circulation fan.
Most space heaters are built for living rooms, not damp greenhouses full of water and soil. A good greenhouse heater should handle humidity, hold a steady temperature on its own and move air so cold pockets do not form near the floor.
We compared heat output, rated coverage, thermostat control, splash protection and fuel type for electric and propane heaters sold in the United States. We picked 7 greenhouse heaters for small hobby houses, large walk-ins and greenhouses with no power line.
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Our Greenhouse Heaters Picks
Best OverallBio Green Palma Greenhouse HeaterA 1,500 watt greenhouse heater with a digital thermostat, a fan-only circulation mode and IPX4 splash protection.Jump to review
Best Value ElectricDr. Infrared DR218 1500W Greenhouse HeaterA simple splash-resistant heater rated for 150 square feet, built for greenhouses and workshops.Jump to review
Best Compact Forced-AirDura Heat EUH1465 Electric HeaterA steel-bodied 1,500 watt ceramic heater with an adjustable thermostat, fan-only mode and overheat shutoff.Jump to review
Best for Large GreenhousesDr. Infrared DR218 3000W Greenhouse HeaterA 3,000 watt heater with high and low settings and a rated coverage of 600 square feet, on a 240 V circuit.Jump to review
Best Propane HeaterMr. Heater Big Buddy 18,000 BTU HeaterThree heat settings up to 18,000 BTU, low-oxygen and tip-over shutoff, and runs on 1 lb cylinders or a 20 lb tank.Jump to review
Best Off-Grid with ThermostatMr. Heater 30,000 BTU Vent-Free Radiant HeaterA vent-free propane heater with a built-in thermostat and battery ignition that needs no electricity.Jump to review
Best for Mini GreenhousesVIVOSUN AeroFlux 700W HeaterA compact 700 watt heater with five heat levels, a temperature sensor and app control for grow tents and mini greenhouses.Jump to reviewWhich Pick Fits Your Zone
Find your zone on the USDA Plant Hardiness Zone Map. Colder zones and larger greenhouses need more heat, and a thermostat matters everywhere.
| Your climate | USDA zones | Our pick | Why it fits |
|---|---|---|---|
| Occasional frost only | 8 to 10 | Dr. Infrared DR218 1500W Greenhouse Heater | Enough heat to keep a small greenhouse above freezing on the few cold nights each year. |
| Regular freezes | 6 to 7 | Bio Green Palma Greenhouse Heater | A digital thermostat holds a set temperature all night without wasting power. |
| Long, hard winters | 3 to 5 | Dr. Infrared DR218 3000W Greenhouse Heater | Twice the output of a 120 V heater for larger, colder greenhouses with a 240 V circuit. |
| No power at the greenhouse | Any | Mr. Heater 30,000 BTU Vent-Free Radiant Heater | Runs on propane with a built-in thermostat and battery ignition. |
A standard 120 V outlet tops out at about 1,500 watts. For more heat, add a 240 V circuit or use propane with good ventilation.
Heater Size by Greenhouse
Treat the sizes below as a starting point: they work out to roughly 15 to 31 W per sq ft for a 6 x 8 ft house (750 to 1,500 W over 48 sq ft). Colder zones need more.
| Greenhouse size | Electric heater size | Notes |
|---|---|---|
| Up to 6 x 8 ft | 750 to 1,500 W | Most plug-in heaters fit |
| 8 x 10 ft | 1,500 W | May need 2 heaters in Zone 5 or colder |
| 10 x 12 ft | 1,500 W + backup | Consider propane |
| Over 12 x 12 ft | Propane or natural gas | Check ventilation rules |
A Closer Look at Each Pick
Best Overall
1. Bio Green Palma Greenhouse Heater
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What We Like
- Designed for greenhouses, with IPX4 splash protection
- Digital thermostat from 32 to 185 F
- Two heat levels, 750 or 1,500 watts
- Fan-only mode moves air to prevent cold spots and mildew
What We Don’t Like
- Rated for about 120 square feet, so large greenhouses need two
- Tops out at 1,500 W on a standard outlet
The Palma is our top pick because it was built for the job. Its thermostat switches the heater on and off to hold your target temperature, so you are not running full power all night. Bio Green says it circulates up to 5,800 cubic feet of air per hour.
The IPX4 rating means it can handle splashes from watering. In summer, the fan-only mode keeps air moving, which helps reduce mildew in a closed greenhouse.
Skip it if: either of these is a deal-breaker for you: rated for about 120 square feet, so large greenhouses need two; tops out at 1,500 W on a standard outlet.
Climate fit: Zones 5 to 9 in greenhouses up to about 120 square feet.
| Power | 750 or 1,500 W, 120 V |
|---|---|
| Heat output | 5,118 BTU |
| Coverage | Up to 120 sq ft |
| Thermostat | Digital, 32 to 185 F |
| Protection | IPX4 splash-proof |
| Weight | 11 lb |
Best Value Electric
2. Dr. Infrared DR218 1500W Greenhouse Heater
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What We Like
- IPX4 splash protection
- Rated for 150 square feet
- Simple, low-maintenance design
- Lightweight and portable
What We Don’t Like
- Only one heat setting
- No built-in thermostat is listed, so pair it with a plug-in thermostat
If you want reliable frost protection without paying for extras, the DR218 1500W is a solid choice. Dr. Infrared markets it for greenhouses and workshops, and it carries an IPX4 splash rating.
With a single setting and no listed thermostat, it runs at full power whenever it is on. Plug it into a greenhouse thermostat controller to cycle it automatically.
Skip it if: either of these is a deal-breaker for you: only one heat setting; no built-in thermostat is listed, so pair it with a plug-in thermostat.
Climate fit: Zones 7 to 10 for frost protection in small greenhouses.
| Power | 1,500 W, 120 V |
|---|---|
| Coverage | Up to 150 sq ft |
| Settings | 1 |
| Protection | IPX4 |
| Weight | 11.5 lb |
| Warranty | 1 year |
Best Compact Forced-Air
3. Dura Heat EUH1465 Electric Heater
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What We Like
- Adjustable thermostat
- Fan-only setting for summer air circulation
- Durable steel body
- Overheat shutoff
What We Don’t Like
- No water-resistance rating is listed
- Keep it on a shelf away from watering
The Dura Heat EUH1465 is a tough little forced-air heater with a thermostat, which many budget workshop heaters skip. It lists coverage up to 250 square feet and has a fan-only mode for warmer months.
It does not list a splash rating, so mount it on a shelf or bench away from hoses and drip lines.
Skip it if: either of these is a deal-breaker for you: no water-resistance rating is listed; keep it on a shelf away from watering.
Climate fit: Zones 6 to 9 in small to medium greenhouses.
| Power | 1,500 W, 120 V |
|---|---|
| Heat output | 5,120 BTU |
| Coverage | Up to 250 sq ft |
| Thermostat | Adjustable |
| Safety | Overheat shutoff |
| Warranty | 1 year |
Best for Large Greenhouses
4. Dr. Infrared DR218 3000W Greenhouse Heater
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What We Like
- 3,000 watts, about twice a standard 120 V heater
- High and low settings
- IPX4 splash protection
- Enclosed heating element
What We Don’t Like
- Needs a 240 V, 20 A outlet
- No thermostat listed
Large greenhouses in cold zones need more heat than a household outlet can deliver. The DR218 3000W runs on a 240 V circuit and lists coverage up to 600 square feet.
Have an electrician install the circuit, and add a thermostat controller so it does not run nonstop.
Skip it if: either of these is a deal-breaker for you: needs a 240 V, 20 A outlet; no thermostat listed.
Climate fit: Zones 3 to 6 in greenhouses over 100 square feet.
| Power | 3,000 W, 240 V, 20 A |
|---|---|
| Coverage | Up to 600 sq ft |
| Settings | High and low |
| Protection | IPX4 |
| Weight | 13 lb |
| Warranty | 1-year limited |
Best Propane Heater
5. Mr. Heater Big Buddy 18,000 BTU Heater
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What We Like
- Three heat settings from 4,000 to 18,000 BTU
- Low-oxygen shutoff and tip-over shutoff
- Runs on two 1 lb cylinders or a 20 lb tank with a hose
- Built-in fan and push-button ignition
What We Don’t Like
- Burning propane adds moisture and combustion gases, so ventilate
- Hose and filter for a 20 lb tank are sold separately
When there is no power at your greenhouse, propane is the practical choice. The Big Buddy has three heat levels, a fan to spread warmth and the safety shutoffs Mr. Heater is known for. On low with a 20 lb tank, Mr. Heater lists up to 96 hours of runtime.
Extension services caution that combustion gases can harm plants, so crack a vent while it runs and install a carbon monoxide detector. Follow the maker indoor-use rules for your state.
Skip it if: either of these is a deal-breaker for you: burning propane adds moisture and combustion gases, so ventilate; hose and filter for a 20 lb tank are sold separately.
Climate fit: Any zone for occasional cold snaps in greenhouses without power.
| Fuel | Propane |
|---|---|
| Output | 4,000, 9,000, 18,000 BTU |
| Coverage | Up to 450 sq ft |
| Safety | Low-oxygen and tip-over shutoff |
| Weight | 14.1 lb |
| Warranty | 3-year limited |
Best Off-Grid with Thermostat
6. Mr. Heater 30,000 BTU Vent-Free Radiant Heater
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What We Like
- Built-in adjustable thermostat
- No electricity needed, battery ignition included
- Low-oxygen safety shutoff
- 30,000 BTU for large spaces
What We Don’t Like
- Vent-free combustion adds moisture, so plan ventilation
- Not for use above 4,500 ft altitude
For a large greenhouse or barn with no power line, this vent-free heater adds something most propane heaters lack: a thermostat. It can hold a set temperature through the night on propane alone.
Because it burns inside the greenhouse, keep a vent cracked, add a carbon monoxide detector and watch humidity, which can encourage mildew.
Skip it if: either of these is a deal-breaker for you: vent-free combustion adds moisture, so plan ventilation; not for use above 4,500 ft altitude.
Climate fit: Zones 3 to 7 in large off-grid greenhouses.
| Fuel | Propane |
|---|---|
| Output | 30,000 BTU |
| Thermostat | Built in |
| Ignition | Battery electronic |
| Safety | Low-oxygen shutoff |
| Warranty | 1-year limited |
Best for Mini Greenhouses
7. VIVOSUN AeroFlux 700W Heater
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What We Like
- Five heat levels
- Temperature sensor with app control and day and night modes
- Compact, space-saving design
- Tip-over and overheat protection
What We Don’t Like
- 700 watts is only enough for small spaces
- No water-resistance rating is listed
The AeroFlux is built for grow tents but works well in mini greenhouses and seed-starting shelves. Its sensor and app let you set a minimum temperature and schedule day and night settings.
At 700 watts, it is not meant for walk-in greenhouses. Keep it dry and away from watering.
Skip it if: either of these is a deal-breaker for you: 700 watts is only enough for small spaces; no water-resistance rating is listed.
Climate fit: Any zone for indoor grow tents and mini greenhouses.
| Power | 700 W, 120 V |
|---|---|
| Heat levels | 5 |
| Control | Sensor, app, day and night modes |
| Safety | Tip-over and overheat protection |
| Size | 9.45 x 4.72 x 9.45 in |
How Far Each Heater Lifts the Temperature
Oregon State University Extension puts heat loss from a single-layer hobby greenhouse at 1.2 BTU per hour for every square foot of exterior surface for every degree F of difference between inside and outside.
Its example houses have 242 sq ft of exterior surface at 6 x 8 ft and 338 sq ft at 8 x 10 ft, which is 290 and 406 BTU per hour for each degree. Dividing each heater’s listed output by those numbers shows how many degrees F above the outside air it can hold.
| Pick | Listed output (BTU per hour) | Rise held in OSU 6 x 8 | Rise held in OSU 8 x 10 |
|---|---|---|---|
| Bio Green Palma Greenhouse Heater | 5,118 (maker) | 17.6 F | 12.6 F |
| Dr. Infrared DR218 1500W Greenhouse Heater | 5,118 (1,500 W x 3.412) | 17.6 F | 12.6 F |
| Dura Heat EUH1465 Electric Heater | 5,120 (maker) | 17.6 F | 12.6 F |
| Dr. Infrared DR218 3000W Greenhouse Heater | 10,236 (3,000 W x 3.412) | 35.2 F | 25.2 F |
| Mr. Heater Big Buddy 18,000 BTU Heater | 18,000 (high) | 62.0 F | 44.4 F |
| Mr. Heater 30,000 BTU Vent-Free Radiant Heater | 30,000 | 103.3 F | 74.0 F |
| VIVOSUN AeroFlux 700W Heater | 2,388 (700 W x 3.412) | 8.2 F | 5.9 F |
To hold the 56-57 F night program Oregon State suggests when it is 20 F outside, you need a rise of about 37 F. That takes roughly 10,700 BTU per hour (about 3,150 W) in the 6 x 8 and 15,000 BTU per hour (about 4,400 W) in the 8 x 10.
A single 1,500 W heater falls well short of both. The 3,000 W DR218 comes close in the 6 x 8 but not the 8 x 10, so size the heater to your coldest night, not to the coverage label.
Greenhouse Heaters Compared Side by Side
| Model | Fuel | Output | Coverage | Control | Splash rating |
|---|---|---|---|---|---|
| Bio Green PalmaBest Overall | Electric, 120 V | 750 or 1,500 W | Up to 120 sq ft | Digital, 32 to 185 F | IPX4 |
| Dr. Infrared DR218 1500WBest Value Electric | Electric, 120 V | 1,500 W | Up to 150 sq ft | Not listed | IPX4 |
| Dura Heat EUH1465Best Compact Forced-Air | Electric, 120 V | 1,500 W | Up to 250 sq ft | Adjustable | Not listed |
| Dr. Infrared DR218 3000WBest for Large Greenhouses | Electric, 240 V | 3,000 W | Up to 600 sq ft | Not listed | IPX4 |
| Mr. Heater Big BuddyBest Propane Heater | Propane | 4,000 to 18,000 BTU | Up to 450 sq ft | Low, medium, high | Not rated |
| Mr. Heater 30,000 BTUBest Off-Grid with Thermostat | Propane | 30,000 BTU | Up to 750 sq ft (listing) | Built-in thermostat | Not rated |
| VIVOSUN AeroFlux 700WBest for Mini Greenhouses | Electric, 120 V | 700 W | Grow tents, small spaces | App and sensor | Not listed |
Which Greenhouse Heaters to Buy
If you have power and a small to medium greenhouse
Get the Bio Green Palma. Its thermostat and splash rating make it the easiest heater to leave running.
If you only need frost protection
The Dr. Infrared DR218 1500W is simple and splash resistant. Pair it with a plug-in thermostat.
If your greenhouse is large and your winters are cold
Choose the Dr. Infrared DR218 3000W on a 240 V circuit.
If there is no power at your greenhouse
The Mr. Heater Big Buddy handles short cold snaps, and the Mr. Heater 30,000 BTU adds a thermostat for all-night heat.
If you grow in a tent or mini greenhouse
The VIVOSUN AeroFlux 700W gives fine control in small spaces.
Heater Safety
- Use a GFCI outlet and a thick outdoor cord.
- Keep heaters 3 ft from plastic sheeting and plants.
- Use a thermostat set to your crops. Colorado State Extension lists 45 to 55°F nights for cool-season crops and 55 to 65°F for warm-season crops.
- Vent propane heaters and use a CO alarm.
- Add bubble wrap to the walls to cut heat loss.
Before You Buy
Enough heat for your greenhouse
Heat needs depend on size, panel type and how cold it gets. A standard 120 V outlet supports about 1,500 watts, or roughly 5,100 BTU. Larger or colder greenhouses need a 240 V heater, two heaters or propane.
A thermostat
A thermostat cycles the heater to hold a set temperature, which saves energy and protects plants if the weather changes overnight. If your heater has none, add a plug-in greenhouse thermostat.
Splash and humidity protection
Greenhouses are wet. Look for an IPX4 or similar rating, and keep heaters off the floor and away from hoses.
Air circulation
Oregon State University extension notes that space heaters without a fan heat unevenly. A fan-forced heater, or a separate circulation fan, keeps cold air from pooling near the floor.
Safe combustion
University of Wyoming extension advises venting combustion heaters outdoors, since gases can harm plants at low levels. With any propane heater, add a carbon monoxide detector and some fresh air.
Our Selection Process
We do not run a test garden. We compared heat output, rated coverage, thermostat control, splash protection, safety shutoffs, warranty terms and owner feedback for electric and propane heaters sold in the United States.
We picked 7 greenhouse heaters that cover small and large greenhouses, sites with and without power, and indoor grow spaces.
Why Trust Garden Guide US
We compare garden gear for American yards using manufacturer specifications, product manuals, warranty terms, cooperative extension guidance and patterns in owner feedback. We do not run a test garden, and every claim comes from a maker, a manual, an extension service or owner feedback. Every guide notes which USDA zones and conditions each pick suits. Read how we review.
Our Verdict
The Bio Green Palma Greenhouse Heater is the one to buy for most backyard greenhouses with power. It was designed for greenhouses, holds temperature with a digital thermostat and handles splashes with an IPX4 rating.
Shopping for more than one piece of gear? Our Greenhouses, Raised Beds and Garden Structures buying guides page groups every guide in this category, and readers who land here often compare the best polycarbonate greenhouses and the best lean to greenhouses next.
For bigger greenhouses in cold zones, step up to the 240 V Dr. Infrared DR218 3000W. With no power line, choose a Mr. Heater propane model and ventilate.
Questions Buyers Ask
What size heater do I need for my greenhouse?
Start with your floor area and climate. Use the sizing table above as a starting point, which works out to roughly 15 to 31 W per sq ft for a 6 x 8 ft house.
The Bio Green Palma is rated for up to 120 sq ft and the DR218 1500W for 150 sq ft. Colder zones and poorly insulated greenhouses need more heat, such as a 240 V heater, two heaters or propane.
Is it safe to use a propane heater in a greenhouse?
Yes, with care. Use a heater with a low-oxygen shutoff, like the Mr. Heater Big Buddy, and follow the maker’s indoor-use rules. Crack a vent while it runs and install a carbon monoxide detector, since University of Wyoming extension notes combustion gases can harm plants at low levels.
What temperature should I keep my greenhouse at night?
Set a thermostat to the needs of your plants. Colorado State Extension lists nighttime temperatures of 45 to 55 F for cool-season crops and 55 to 65 F for warm-season crops, with a 55 F minimum night for tomatoes and peppers.
A thermostat avoids wasting power on extra heat. The Bio Green Palma’s digital thermostat holds a target all night. Check what your own crops need, since tender plants may want more.
Can I use a regular space heater in a greenhouse?
Only with caution. Most space heaters are built for living rooms, not damp greenhouses, so look for IPX4 splash protection like the DR218 1500W has. The Dura Heat EUH1465 lists no splash protection, so keep it on a shelf away from watering. Use a GFCI outlet and keep heaters 3 ft from plastic and plants.
How can I cut greenhouse heating costs?
Insulate and control. Add bubble wrap to the walls to cut heat loss, seal gaps and group tender plants together. A thermostat cycles the heater to hold a set temperature instead of running all night, and you can pair a basic model like the Dr. Infrared DR218 1500W with a plug-in thermostat.
Sources and Further Reading
- USDA Plant Hardiness Zone Map, USDA Agricultural Research Service
- Hobby Greenhouses, Oregon State University Extension
- Greenhouse Unit Heaters: Types, Placement, and Efficiency, University of Wisconsin-Madison
- Hobby Greenhouse Design, University of Wyoming Extension
- Heating Greenhouses, University of Florida IFAS Extension
- Greenhouse Production, Penn State Extension
- Growing Vegetables in a Hobby Greenhouse, Colorado State University Extension
