Choose, install, and set up a space heater to keep your greenhouse within a temperature range suited to your plants. This guide is for home gardeners who can measure the growing space and use basic hand tools. Plan for 1–3 hours to prepare and install the heater, then check its performance overnight before relying on it during cold weather.
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Buyplus 1500W Greenhouse Heater with Digital Thermostat – Red
- ✔ Power: 1500 watts
- ✔ Rated output: 5118 BTU
- ✔ Listed coverage: Up to 215 sq ft
Greenhouse Heater with Thermostat, 1500W Outdoor Heater for Patio, Auto Temp Control & Overheat Protection, Non-Slip Cushion, Ele…
- ✔ Power output: 1500 watts
- ✔ Voltage: 120 V AC
- ✔ Amperage: 13 A
Buyplus Greenhouse Heater with Digital Thermostat, 1500W Electric Space Heater for Patio, Garage, Greenhouse (Black)
- ✔ Power: 1500 watts
- ✔ Listed coverage: Up to 215 sq ft
- ✔ Thermostat range: 40°F–108°F
Difficulty: Beginner | Time: 1–3 hours for setup; allow an overnight check
What You’ll Need
Tools & Materials:
- Tape measure
- Thermometer with minimum and maximum readings, or a greenhouse temperature monitor
- Heater manual and mounting hardware, if supplied
- Outdoor-rated extension cord only if the heater manual permits one
- Fire extinguisher rated for the heater’s fuel and electrical risks
Knowledge:
- Basic familiarity with your plants’ minimum temperature needs
- Ability to read heater labels and follow the manufacturer’s installation instructions
Check local electrical and fire-safety requirements before installation. In a damp greenhouse, use equipment rated for the environment and a correctly protected circuit. Never use a household heater, damaged cord, or fuel-burning heater in an enclosed space unless the manufacturer explicitly approves that use and specifies the required ventilation.
Buyplus 1500W Greenhouse Heater with Digital Thermostat – Red
For greenhouse growers who want temperature feedback beyond the heater housing, the Red Buyplus is our leading choice. Its digital thermostat pairs with a waterproof probe, which can be positioned to monitor conditions where plants are growing rather than relying only on the air next to the unit. That makes its control setup more greenhouse-focused than the Black Buyplus, whose description lists a digital thermostat but does not specify a separate probe.At 1500W, it shares the same basic output as the other two picks and is listed for spaces up to 215 square feet. That figure is a guide, not a guarantee: a drafty greenhouse or a sharp overnight temperature drop may overwhelm a portable heater of this size. The fan-only mode can circulate air without full heat, and the adjustable angle and 7.5-foot cord support flexible floor placement. By comparison, the third pick has an additional low-heat mode, which may suit growers who prefer a stepped power choice.Overheat protection and a self-resetting heat breaker add safeguards, but they do not remove the need for careful clearance from plants, plastic coverings, and other materials. We would skip this unit for a large uninsulated greenhouse or a site without a suitable outlet. Its strongest case is more informed thermostat placement, not greater heating capacity.
Pros:
- Digital thermostat with waterproof probe
- Two modes: fan-only and 1500W heat
- Adjustable 0–45° angle and 7.5-foot cord
- Overheat protection with self-resetting heat breaker
Cons:
- 1500W output may be insufficient for larger or poorly insulated greenhouses
- Requires AC power and does not provide fuel-free placement flexibility
Best for: Growers heating a small greenhouse who want to monitor temperature with a separate waterproof probe.
Not ideal for: Owners of large, drafty greenhouses or locations without a suitable AC outlet.
Bottom line: Choose the Red Buyplus when probe-based temperature monitoring is more useful to us than the third model’s extra low-heat setting.
“Choose the Red Buyplus when probe-based temperature monitoring is more useful to us than the third model’s extra low-heat setting.”
Greenhouse Heater with Thermostat, 1500W Outdoor Heater for Patio, Auto Temp Control & Overheat Protection, Non-Slip Cushion, Ele…
When we want a middle setting between air circulation and full heating, this three-mode PTC heater has the most operating flexibility in the group. Its fan-only, low-heat, and high-heat modes create a stepped choice the two Buyplus heaters do not list. That can be useful when a greenhouse needs some supplemental warmth without immediately running the unit at its full 1500W setting.The built-in thermostat and clear temperature display support basic temperature management, while the portable handle, non-slip cushion, and adjustable angle help with repositioning. Compared with the Red Buyplus, however, the description does not specify a waterproof remote probe. We would weigh those features differently: choose the Red for the stated probe, or this model when selectable heat levels matter more. Its stated two-second heat-up is a product claim, not a reason to expect it to warm a whole greenhouse instantly.The main limits are familiar: it draws power from a 120V AC outlet, and the supplied details do not give a coverage figure. Without one, we should be cautious about assuming it can handle a particular greenhouse size. It is a practical fit for smaller areas where low-heat operation is valuable, but less compelling when coverage certainty or remote temperature sensing is the priority.
Pros:
- Three modes: fan-only, low heat, and high heat
- Built-in thermostat with temperature display
- Portable handle, non-slip cushion, and adjustable angle
- 1500W output with overheat protection
Cons:
- Requires a standard AC outlet
- No remote or smartphone integration
- Description does not provide a heating-area rating
Best for: Growers with a compact greenhouse or grow tent who value a low-heat setting alongside fan-only and full heat.
Not ideal for: Buyers who need a stated coverage area, a specified waterproof probe, or remote and smartphone controls.
Bottom line: Pick this heater for its extra low-heat step, while choosing the Red Buyplus if probe-based monitoring is the deciding factor.
“Pick this heater for its extra low-heat step, while choosing the Red Buyplus if probe-based monitoring is the deciding factor.”
Buyplus Greenhouse Heater with Digital Thermostat, 1500W Electric Space Heater for Patio, Garage, Greenhouse (Black)
The Black Buyplus is a straightforward choice for buyers who want a digital thermostat and two operating modes without prioritizing a separate probe or extra heat levels. It shares the Red Buyplus’s 1500W rating, 40°F–108°F thermostat range, and stated coverage of up to 215 square feet. For a buyer comparing those two, the Red version has the more clearly specified greenhouse monitoring setup; the Black model’s appeal is its simple combination of thermostat control and fan-only or full-heat operation.Its fan-only setting uses 25W, offering air movement without full heating power. The 7.5-foot cord and portable handle can help us position it where an outlet allows, and the non-slip base is useful on a stable floor. Against the three-mode heater, though, it lacks a listed low-heat setting, so the choice is essentially circulation or 1500W heat. The description also specifies no built-in timer or remote, which means we should expect to adjust settings at the unit.Like its near-twin, this model is best viewed as supplemental heat for a suitably sized, reasonably protected space. The up-to-215-square-foot figure should not override local conditions such as insulation or cold exposure. We would choose it for basic thermostat-led heating, but move to the Red for probe placement or to the three-mode model for a lower heat step.
Pros:
- Digital thermostat with a 40°F–108°F range
- Fan-only and 1500W heating modes
- Listed coverage up to 215 sq ft
- Portable handle, non-slip base, and 7.5-foot cord
Cons:
- No built-in timer or remote control
- No low-heat setting is listed
- 1500W capacity and AC power requirement limit where it is suitable
Best for: Buyers who want a digital thermostat and fan-only option for a small greenhouse and prefer simple controls.
Not ideal for: Growers who want a separate waterproof probe, low-heat mode, timer, or remote operation.
Bottom line: Choose the Black Buyplus for basic thermostat control, but compare it closely with the Red model if probe-based monitoring matters.
“Choose the Black Buyplus for basic thermostat control, but compare it closely with the Red model if probe-based monitoring matters.”
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Before You Start
Find the coldest temperature your plants can tolerate and choose a thermostat setting that keeps the greenhouse above it. A heater’s output is usually listed in watts or BTU per hour, but the required capacity also depends on greenhouse size, insulation, glazing, wind exposure, and the difference between indoor and outdoor temperatures. Use the manufacturer’s sizing guidance or a reputable heat-loss calculator; do not select a heater by floor area alone.
Inspect the greenhouse for gaps and damaged glazing. Seal drafts where practical, while preserving any ventilation required for plants and fuel-burning equipment. Keep water away from electrical connections and identify a clear path from the heater to an outlet or approved fuel supply.
Step-by-Step Instructions
Step 1: Measure the greenhouse
Measure the interior length, width, and height, and note the glazing type, insulation, and major drafts. Record the lowest outdoor temperature you expect the heater to handle. Use these details with the heater maker’s sizing chart or a heat-loss calculator to estimate the required output.
Tip:Keep the calculation and the plant temperature target separate: the calculation helps size the heater, while the thermostat setting protects the plants.
Check: You have the greenhouse dimensions, a realistic cold-weather design temperature, and a heater output range to compare with product specifications.
Step 2: Choose a heater and power source
Select a greenhouse-rated heater with a thermostat and appropriate safety features, such as overheat protection and tip-over protection where applicable. Match its output to your estimate. Confirm that the electrical circuit can support its wattage, or that the fuel model is approved for greenhouse use and has clear ventilation requirements.
Tip:Electric heaters avoid combustion gases but can overload circuits. Fuel-burning heaters can add moisture and combustion products, so use only models approved for the setting and follow their ventilation and clearance instructions.
Check: The heater label and manual specify an approved use, adequate output, required clearances, and a compatible power source.
Step 3: Prepare the installation area
Choose a level, stable location that meets the manual’s clearance distances from plants, plastic, fabric, stored fuel, and other combustible materials. Keep the heater away from irrigation spray and standing water. Clear leaves, pots, and tools from the surrounding area.
Tip:Do not place a portable heater where it can be knocked over or where its hot airflow will strike leaves at close range.
Check: The heater location is dry, stable, unobstructed, and meets all clearances printed in the manual.
Step 4: Install the heater safely
Mount or place the heater exactly as its manual directs. For an electric model, connect it directly to a properly rated outlet unless the manual explicitly allows a specific extension cord. Keep cords off wet floors, away from sharp edges, and out of walkways. For a fuel model, use the specified fuel and regulator, check connections as instructed, and provide required ventilation.
Tip:Do not use a power strip or undersized extension cord for a high-wattage heater. Stop if a plug, cord, or outlet feels hot, smells burnt, or shows damage.
Check: The heater is secure, the power or fuel connection follows the manual, and the required ventilation and clearances remain open.
Step 5: Set up temperature monitoring
Place a thermometer or temperature sensor near plant height, away from the heater’s direct airflow, doors, and glazing. Set the thermostat to the minimum temperature your plants require, allowing a small margin for sensor variation. If the heater has a separate thermostat probe, position it as directed by the manufacturer.
Tip:A sensor beside the heater can read warmer than the rest of the greenhouse and switch the heater off too soon.
Check: The monitor displays a stable reading from a representative growing area, and the thermostat target is recorded.
Step 6: Run a supervised test
Turn on the heater while you are present and observe it through a full heating cycle. Confirm that the thermostat starts and stops the heater near the set point. Check for unusual noise, smoke, fuel odor, hot plugs, or airflow blocked by nearby objects. Follow the manual for any first-use odor or commissioning procedure.
Tip:If you smell fuel, see smoke, or notice a hot electrical connection, switch the heater off if safe, leave the area if needed, and address the cause before use.
Check: The heater cycles as intended, the temperature begins to rise, and there are no warning signs or abnormal smells.
Step 7: Check overnight performance
After the supervised test, monitor the greenhouse overnight during representative cold weather. Review the minimum and maximum readings in the morning. If the temperature fell below the plant-safe target, check for drafts, sensor placement, thermostat setting, and heater capacity before increasing the setting or adding another heater.
Tip:Do not leave a heater unattended overnight until you have confirmed stable operation and safe clearances. Continue to follow any supervision limits in the manual.
Check: The recorded minimum stays above the target temperature, and the heater and surrounding area show no signs of overheating or moisture damage.
Common Mistakes to Avoid
- Choosing a heater based only on greenhouse floor area. — Account for glazing, drafts, insulation, and expected outdoor lows using the maker’s sizing guidance or a heat-loss estimate.
- Putting the thermostat sensor beside the heater. — Place it near plant height in a representative growing area, away from direct heat and cold drafts.
- Using an unsuitable extension cord or power strip. — Follow the heater manual’s connection requirements and confirm the outlet and circuit rating before use.
- Blocking ventilation or placing combustibles too close. — Maintain the manufacturer’s clearances and ventilation requirements; keep leaves, plastic, pots, and fuel away from the heater.
Troubleshooting
Problem: The greenhouse stays colder than the thermostat setting.
Solution: Check that the sensor is not near a draft, verify the thermostat setting, inspect glazing and door seals, and compare heater output with the sizing estimate. Add insulation or use a correctly sized approved heater if heat loss exceeds capacity.
Problem: The heater switches on and off very frequently.
Solution: Move the sensor away from direct airflow and sunlight, check for a loose probe, and confirm that the heater is not too large for the space. Follow the manual’s guidance on thermostat placement and cycling.
Problem: A breaker trips or a plug becomes hot.
Solution: Turn the heater off and unplug it if safe. Do not reset repeatedly or continue using a hot or damaged connection. Have the circuit and heater checked by a qualified electrician, and use a properly rated dedicated circuit if required.
Problem: Condensation increases or there is a fuel odor.
Solution: Turn off a fuel-burning heater if safe, ventilate the greenhouse, and leave the area if the odor is strong or persistent. Check the manual’s ventilation and fuel connection instructions; have leaks assessed by a qualified technician before restarting.
What Success Looks Like
The heater is installed according to its manual, connected to a suitable power or fuel source, and clear of water and combustible materials. A thermometer at plant height shows that the greenhouse remains at or above the chosen plant-safe minimum through a cold overnight period. The heater cycles normally, and there are no hot connections, fuel odors, smoke, or signs of overheating.
Next Steps
Check the temperature monitor each morning during cold weather and inspect the heater, cord, fuel connections, and clearances regularly. Clean and maintain the unit on the schedule in its manual, with power disconnected and the heater cool. Recheck performance when you change glazing, add insulation, move the heater, or face colder weather. If the heater cannot maintain the target safely, consult a qualified electrician or heating technician before changing the electrical supply or fuel setup.
Frequently Asked Questions
What temperature should I set a greenhouse space heater to?
Set it to the lowest temperature your plants can safely tolerate, using a thermometer near plant height to confirm the actual conditions. Different crops and growth stages have different limits; check reliable care guidance for your plants.
Can I use a household space heater in a greenhouse?
Use one only if its manufacturer approves it for the greenhouse’s damp conditions and the installation meets the heater’s electrical, clearance, and ventilation requirements. Many household models are not designed for damp environments.
Can I leave a greenhouse heater on overnight?
Follow the manual’s supervision instructions. Before relying on overnight operation, complete a supervised test, verify safe installation, and confirm with overnight temperature readings that the heater maintains the target without overheating or electrical problems.
Should I use an electric or fuel-burning greenhouse heater?
Choose based on available power, heater capacity, operating conditions, and installation requirements. Electric models avoid combustion gases but need a suitable circuit. Fuel-burning models need approved ventilation and careful fuel handling, and may add moisture.
