Choosing a greenhouse space heater is less about picking the hottest unit and more about matching heat delivery to the building, available utilities, and the cost of keeping plants above their safe temperature. Electric and propane heaters are the two common choices, but they solve different problems: electric models make temperature control straightforward where power is available, while propane models can provide strong heat in spaces where electrical service is limited or during outages.
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SmterCon Greenhouse Heater with Digital Thermostat and Auto Power Control
- ✔ Heat output: 1500 watts
- ✔ Fuel type: Electric
- ✔ Amperage: 15 A
VEVOR 1500W Greenhouse Heater with Thermostat, Fan & High Heat Modes, Adjustable Angle, IPX4 & Overheat Protection
- ✔ Power output: 1500 watts
- ✔ Voltage: 120 V
- ✔ Amperage: 12.5 A
VEVOR 1500W Electric PTC Greenhouse Heater with Fan, Adjustable Angle and Overheat Protection
- ✔ Power output: 1500 watts
- ✔ Voltage: 120 V
- ✔ Amperage: 8.33 A
The central tradeoff is convenience and control versus fuel independence and heat output. Electric heat is often the better fit for a small or medium greenhouse that has a suitable circuit and needs steady, closely managed warmth. Propane makes more sense for a larger or poorly served structure where a fuel supply is practical and the owner can provide proper ventilation and safety controls. The comparison below focuses on operating costs, capacity, control, installation, safety, and resilience so you can choose for your actual growing conditions.
At a Glance
| Criteria | Electric greenhouse space heaters | Propane greenhouse space heaters | Winner |
|---|---|---|---|
| Heat output and greenhouse size | Commonly suited to smaller or well-insulated spaces; capacity is limited by circuit and unit rating. | Can provide substantial heat for larger spaces, subject to heater rating and ventilation requirements. | Depends |
| Operating cost | Depends on electricity rates, heat loss, and runtime; can become costly in a leaky or cold greenhouse. | Depends on propane prices and consumption; can be economical where electricity is expensive, but fuel costs vary. | Depends |
| Temperature control | Generally easy to pair with a thermostat; no combustion process to regulate. | Thermostat control is available on some models, but settings and operation vary by heater. | A |
| Installation and utility needs | Needs an appropriately rated electrical circuit and weather-appropriate placement. | Needs propane cylinders or a tank, safe fuel connections, and adequate ventilation. | A |
| Moisture, combustion, and air quality | No combustion gases or combustion-generated water vapor at the heater. | Combustion adds exhaust and water vapor; venting and air exchange matter for plant and human safety. | A |
| Outage resilience | Stops working during a power outage unless backed by a suitable backup system. | Can operate without grid electricity if the heater does not require powered ignition or fans. | B |
| Ongoing upkeep | Usually simple: inspect cords, plugs, housing, and thermostat. | Requires fuel-level checks and inspection of connections, burner, and safety components. | A |
SmterCon Greenhouse Heater with Digital Thermostat and Auto Power Control
For growers who want a heater to respond to temperature changes rather than rely on manual switching, the SmterCon is our best overall pick. Its digital thermostat is described as automatically turning the unit on and off to maintain a selected temperature. That is a more useful greenhouse distinction than simply offering 1500W: repeated manual adjustments are inconvenient, while automatic cycling can help us keep conditions steadier when the space cools. The listing also describes adjustable ventilation, so the unit can circulate air when active heating is not the priority.Compared with the two VEVOR heaters, SmterCon puts more emphasis on set-point control than on aiming heat. The larger VEVOR provides a wider 25° angle adjustment, and the compact VEVOR is lighter, but neither supplied description specifies a digital thermostat with automatic on/off control. If we want to maintain a target setting with less intervention, SmterCon has the clearest advantage. Its stated coverage of about 120 square feet may help small-space buyers assess fit, but actual performance will depend heavily on greenhouse construction and outdoor conditions.There are practical qualifications. The listing specifies a 15A requirement, so we should confirm that the intended circuit can support the heater and follow the manual rather than assume any outlet is suitable. Fan noise may also matter in a quiet indoor growing room. And although the product description mentions fire-proof materials and independent overheat protection, those features do not remove the need for proper clearance, a dry and appropriate location, and supervision consistent with the manufacturer’s guidance. Choose this model for control, not because its coverage claim guarantees warmth in every greenhouse.
Pros:
- Digital thermostat with automatic on/off control helps maintain a selected temperature with less manual switching.
- Adjustable ventilation provides an air-circulation option beyond heating.
- Independent overheat protection is listed as part of the safety design.
- Stated coverage of about 120 square feet gives small-space buyers a reference point, subject to real conditions.
Cons:
- The stated 15A requirement may limit which circuits are suitable.
- Fan operation can be noisy in quiet growing areas.
- Coverage is limited and will vary with insulation, drafts, and outside temperature.
Best for: Small-greenhouse growers who value a digital set point and automatic on/off temperature control, and who can meet the stated 15A electrical requirement.
Not ideal for: Buyers with a circuit that cannot support the stated requirement, anyone especially sensitive to fan noise, or owners of large or poorly insulated greenhouses expecting one compact heater to cover the entire space.
Bottom line: We rank SmterCon first for its automatic digital temperature control, provided its electrical requirement and fan noise suit the growing space.
“We rank SmterCon first for its automatic digital temperature control, provided its electrical requirement and fan noise suit the growing space.”
VEVOR 1500W Greenhouse Heater with Thermostat, Fan & High Heat Modes, Adjustable Angle, IPX4 & Overheat Protection
The larger VEVOR is the better match when where the air goes matters as much as heat output. Its 25° adjustable angle gives us more room to point airflow toward a bench or plant area than the compact VEVOR’s 15° adjustment. It also has heating and fan modes, allowing the unit to move air without selecting heat. For a small greenhouse where one location needs more directed airflow, that combination is more versatile than a heater that only offers a fixed direction.Its built-in thermostat is listed with two temperature settings and a range of 40°F to 108°F, but the supplied information does not say that it automatically cycles digitally around a chosen set point. That makes it less compelling than the SmterCon for hands-off temperature maintenance. Conversely, the VEVOR’s clearer angle adjustment makes it a more flexible choice for positioning heat than the SmterCon, whose description stresses adjustable ventilation rather than a specified aim angle. At 7.1 pounds, however, it is nearly twice the listed weight of the 3.7-pound compact VEVOR, so moving it repeatedly between beds is less appealing.The listed 1500W output and 120V supply make this a substantial plug-in heater for a small growing area, but we should still verify the circuit and follow the product’s electrical instructions. IPX4 and overheat protection are listed, yet we should not read those details as permission to expose the unit to water or leave it in unsuitable conditions. This pick makes the most sense when directional airflow and a broader thermostat range are more important than portability or digital automation. Skip it if frequent relocation is part of the routine or if precise automatic control is essential.
Pros:
- 25° adjustable angle offers more direction-setting range than the compact VEVOR’s 15° adjustment.
- Heating and fan modes support both warmth and air circulation.
- Built-in thermostat has a stated 40°F–108°F range.
- Portable handle, stable base, and listed IPX4 and overheat protection add practical features.
Cons:
- At 7.1 pounds, it is heavier than the compact VEVOR and less convenient to move often.
- The listing gives two temperature settings but does not specify digital automatic cycling like SmterCon.
- A 1500W heater may not meet the needs of a large or poorly insulated greenhouse.
Best for: Growers who want to angle airflow toward a specific section of a small greenhouse and also want a fan-only mode.
Not ideal for: Anyone who frequently carries a heater between locations, needs clearly specified digital auto-cycling, or is heating a large greenhouse with substantial heat loss.
Bottom line: We choose this VEVOR when adjustable direction matters more than low weight or the SmterCon’s automatic digital control.
“We choose this VEVOR when adjustable direction matters more than low weight or the SmterCon’s automatic digital control.”
VEVOR 1500W Electric PTC Greenhouse Heater with Fan, Adjustable Angle and Overheat Protection
When space and carrying weight are the deciding factors, the compact VEVOR PTC heater is the easiest of these three to place and reposition. It measures 8.27 × 6.3 × 8.66 inches and weighs 3.7 pounds, compared with 7.1 pounds for the other VEVOR. Its 1500W output is the same on paper, but the smaller body makes it a more practical choice for a grow tent, flower room, or compact greenhouse where a larger heater would be awkward to position. Heat and fan modes also allow air movement without using the heating setting.We would choose it over the larger VEVOR when portability beats a wider aim angle; the tradeoff is a 15° adjustment instead of 25°. Its low and high heat settings are straightforward, but they offer less fine-tuning than SmterCon’s digital thermostat and automatic on/off control. The listed 8.33A draw is also lower than the SmterCon’s stated 15A requirement, although buyers should check the product instructions and circuit rather than relying on a spec comparison alone. For someone who wants a compact, manually controlled heater, that balance can be more useful than paying for control features they do not need.Its limits are equally important. Two heat settings are not the same as a precise thermostat, and the supplied listing does not establish a greenhouse coverage area. The stated maximum temperature of 75°C describes a product specification, not a promise that the heater can bring a greenhouse of any size to a suitable growing temperature. This is a small-space, close-range option, not our pick for maintaining conditions across a broad or drafty structure. Choose it for a modest area and easy repositioning; choose SmterCon for automatic set-point control or the larger VEVOR for more angle adjustment.
Pros:
- Listed at 3.7 pounds, making it much lighter than the other VEVOR model.
- Compact dimensions suit tighter growing spaces and make placement easier.
- Low and high heat settings plus fan mode cover basic heating and circulation needs.
- 15° adjustable angle and overheat protection are included.
Cons:
- Two heat settings provide less fine control than SmterCon’s digital thermostat.
- Its 15° adjustment is narrower than the larger VEVOR’s 25° range.
- The supplied information does not state a coverage area for greenhouse sizing.
Best for: Growers with a compact greenhouse, grow tent, or flower room who want a lighter heater with basic heat and fan modes.
Not ideal for: Buyers who need precise thermostat control, wider airflow adjustment, or evidence that a single unit can heat a larger greenhouse.
Bottom line: We recommend this compact VEVOR for small spaces where low weight and simple controls matter more than thermostat precision.
“We recommend this compact VEVOR for small spaces where low weight and simple controls matter more than thermostat precision.”
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Key Differences
Electric heaters favor controlled, low-hassle operation. A thermostat can cycle the unit as temperatures change, and the heater does not add combustion exhaust or water vapor to the growing space. That makes electric a strong default for a greenhouse with a suitable circuit, especially when the goal is frost protection or stable temperatures in a compact structure. Its limits are practical: a heater cannot exceed the capacity of its circuit, and the cost of running it depends on local electricity rates and how quickly the greenhouse loses heat.
Propane shifts the burden from electrical capacity to fuel management and air safety. It can deliver considerable heat and may keep working through a grid outage, which matters in cold climates or at sites with unreliable service. But that independence is not automatic: some models need electricity for ignition or a fan, and all combustion appliances must be operated according to their instructions, with suitable ventilation and working safety features. Propane can be a sensible answer to a specific capacity or outage problem, but it is not a universal upgrade over electric.
The better purchase depends on heat demand, not just heater type. Insulation, glazing, drafts, greenhouse volume, desired night temperature, and local utility and fuel prices all affect the result. Before buying either, estimate the heat loss and check the manufacturer’s greenhouse-use instructions, circuit requirements, and clearances. If the space is poorly sealed, reducing heat loss can improve comfort and operating cost more than moving to a more powerful heater.
Detailed Comparison
Heat output and greenhouse size (moderate difference)
Winner: Depends on the site and unit rating; moderate difference. Propane models can suit larger spaces when electrical service is constrained, while electric units are often enough for small, insulated greenhouses. Neither fuel type guarantees adequate heating: the heater’s rated output must match the greenhouse’s heat loss, and electrical circuit limits can rule out a high-wattage electric unit. For a small hobby greenhouse, propane’s extra capacity may be unnecessary. For a large structure, calculate the load rather than assuming any portable heater will keep it warm.
Operating cost (major difference)
Winner: Depends on local rates and heat demand; major financial difference over time. Electric heaters are simple to price using the unit’s power draw, local electricity rate, and expected runtime. Propane cost depends on fuel price and consumption, which can fluctuate and may include delivery or cylinder-refill costs. A well-insulated greenhouse with short heating periods may favor electric, while a high-demand site with expensive electricity may make propane attractive. Compare estimated seasonal costs before treating either as the cheaper option.
Temperature control (Electric greenhouse space heaters wins — moderate)
Winner: Electric; moderate difference. Many electric heaters pair readily with a thermostat, making it easier to maintain a set temperature without manually tending the unit. Propane heaters also come with thermostat features in some designs, but the control options vary, and operation can involve fuel and ventilation checks. For seedlings, tropical plants, or any collection sensitive to temperature swings, electric is generally the more straightforward choice. Check that a thermostat is rated for the heater and environment rather than assuming one is included.
Installation and utility needs (Electric greenhouse space heaters wins — moderate)
Winner: Electric for a site with a suitable circuit; moderate difference. Electric units avoid fuel storage and connection work, but they still need the correct circuit, safe placement, and protection from moisture as directed by the manufacturer. Propane avoids dependence on a high-capacity electrical circuit, but requires an appropriate cylinder or tank and sound fuel connections. For a greenhouse without reliable electrical service, propane can be the practical winner. Where power is already available, electric usually asks less of the owner.
Moisture, combustion, and air quality (Electric greenhouse space heaters wins — major)
Winner: Electric; major difference for indoor air management. Electric heaters produce heat without combustion at the unit, so they do not release combustion exhaust or combustion-generated moisture into the greenhouse. Propane combustion produces exhaust and water vapor, and poor ventilation can create dangerous conditions for people and plants. Use propane only in a model approved for the intended setting, following its ventilation and clearance instructions. If managing exhaust or extra humidity is difficult, electric is the clear choice.
Outage resilience (Propane greenhouse space heaters wins — moderate)
Winner: Propane when the model can operate independently; moderate difference. A propane heater with non-electric ignition and no required fan can provide heat during a power failure, a valuable safeguard when a cold night could damage plants. Some propane units still require electricity, so verify the exact model before counting on backup heat. Electric heaters stop when grid power does. If outages are common, a properly chosen propane unit can add resilience; otherwise this advantage may not justify fuel handling.
Ongoing upkeep (Electric greenhouse space heaters wins — minor)
Winner: Electric; minor-to-moderate difference. Electric units generally need routine visual checks of the cord, plug, housing, and thermostat. Propane units add fuel monitoring and inspection of the burner, connections, and safety parts, with servicing determined by the manufacturer. Neither should be ignored, particularly in a damp environment. If you want the least routine involvement, electric is usually easier; if you already manage propane equipment, the extra checks may be minor.
Electric greenhouse space heaters: Pros and Cons
Pros:
- Straightforward thermostat-based temperature control on many setups.
- No combustion exhaust or combustion-generated moisture at the heater.
- No cylinders, tank, or fuel connections to manage.
- Usually simpler routine upkeep.
Cons:
- Requires an adequately rated electrical circuit.
- Cannot provide heat during an outage without backup power.
- Long runtimes can be expensive where electricity costs are high.
- Capacity may be insufficient if the greenhouse loses heat quickly.
Propane greenhouse space heaters: Pros and Cons
Pros:
- Can supply substantial heat where electrical capacity is limited.
- Some models can provide heat during grid outages.
- May have a lower operating cost in locations where propane is economical.
- Does not depend on a high-capacity electrical connection if the model operates without power.
Cons:
- Requires fuel storage, refills, and safe connections.
- Combustion exhaust and added moisture make ventilation a serious requirement.
- Operating costs depend on variable propane prices and usage.
- Some models need electricity for ignition or fans, limiting outage use.
Who Should Choose What
Choose Electric greenhouse space heaters if:
- You have a suitable circuit and want simple thermostat-controlled heat.
- Your greenhouse is small or medium-sized, reasonably insulated, and needs steady frost protection.
- You want to avoid combustion exhaust, added combustion moisture, and fuel handling.
- You prefer low-maintenance operation and can rely on grid power.
Choose Propane greenhouse space heaters if:
- Your greenhouse needs more heat than its electrical service can practically support.
- You need backup heat during outages and have verified that the model operates without grid power.
- Propane is readily available and its expected seasonal cost compares favorably with electricity.
- You can follow the heater’s ventilation, clearance, fuel-storage, and maintenance requirements.
Skip both if: Skip portable heaters as the sole solution if the greenhouse is highly drafty, the required temperature cannot be maintained safely, or neither fuel can be used within the available circuit, ventilation, and installation limits. Improve insulation and sealing, or seek a properly sized fixed heating system.
Value for Money
There is no reliable price winner without local rates, fuel prices, and a realistic estimate of runtime. Electric often delivers better value for modest heat needs because installation and routine operation are simpler. Paying more for propane equipment can be worthwhile if it solves a real constraint—limited electrical capacity, high electricity costs, or a meaningful need for outage heat. It is poor value if the greenhouse is small, power is reliable, and the propane heater’s additional capacity will rarely be used.
Compare total seasonal cost, not just the sticker price: include expected energy use, circuit or fuel setup, refills or delivery, and any equipment needed for safe operation. Also account for heat loss. Weather stripping, insulation where suitable, and reducing drafts can lower the required runtime for either heater. A lower-cost heater that cannot hold the needed temperature is not a bargain, while paying for excess capacity does not fix a poorly sealed structure.
Final Verdict
For most owners with a suitable electrical circuit and a small or medium greenhouse, choose an electric heater. It is easier to control, avoids combustion inside the growing space, and asks less of you day to day. Choose propane when electrical capacity or outage resilience is the deciding problem and you can manage ventilation and fuel safely. The biggest deciding factor is whether your greenhouse needs propane’s fuel independence and potential capacity enough to justify the added operating and safety responsibilities. If heat demand is unclear, size the system to the structure before buying either.
Frequently Asked Questions
Are electric or propane heaters cheaper to run in a greenhouse?
Neither is always cheaper. Compare local electricity and propane prices against the heater’s rated consumption and expected runtime. A leaky greenhouse can make either option expensive, so estimate heat loss and seasonal use before choosing.
Can I use a propane space heater inside a greenhouse?
Only use a heater whose manufacturer permits the intended setting, and follow its ventilation, clearance, fuel, and operating instructions. Propane combustion produces exhaust and water vapor; never treat a greenhouse as safe for an unvented heater without checking the product’s requirements and applicable safety guidance.
Will a propane greenhouse heater work during a power outage?
Some will, but not all. Check whether the exact model needs electricity for ignition, a fan, or controls. A model that requires power will not provide dependable outage heat unless you have an appropriate backup source.
What matters more: heater type or greenhouse insulation?
Both matter, but insulation and draft control can cut the amount of heat either system must supply. If the structure loses heat rapidly, a larger heater may raise costs without fixing the underlying problem. Reduce heat loss, then size the heater for the remaining demand.
