5 Best Heaters For Greenhouses

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If you have a greenhouse where plants are sensitive to cold temperature conditions, you need not worry about the weather. The new range of heaters from trusted manufacturers is more reliable, durable, and efficient at sustaining a constant temperature across the region of your greenhouse.

So, say goodbye to those plastic-clad heaters that you used before and get sturdy, hard-built, safe-to-use, and technologically advanced heaters that will not only improve your user experience as they are easy to use, but they will also serve well your greenhouse, with a wide range of operating temperatures.

These new portable heaters are convenient to carry, and they can be placed on the ground. They also confirm the new standards set for such greenhouse heaters. Now, the weather will not inhibit you from working in these greenhouses as the new heaters are user-friendly and cost-effective. Moreover, these heaters are versatile so that you can use them in any other small space too. 

How Many Heaters Will I Need For My Greenhouse

It may seem a confusing task, knowing if a heater will be sufficient to heat your greenhouse to the required temperature. Perhaps, you may need more than one heater to get your greenhouse at an optimal growing temperature, but how can you know for sure.

You need to know how many BTUs (British thermal units) are needed to keep your greenhouse at its required temperature (Use the calculator below)

Then ensure the BTU measurement is closely matched by the BTU output of the greenhouse heater; either by using 1 heater or by using multiple heaters.
(Check out the product description table below)

British thermal units

The amount of heat required to raise the temperature of 1 pound (0.4 kilogram) of water 1°F.


To find out how many BTUs your greenhouse needs, use the BTU calculator below and then match that measurement to greenhouse heaters BTU output measurments in the product description table below.

Greenhouse Heater BTU Calculator

Use the calculator below to give a BTU measurement specific to your own greenhouse.

Taking that BTU measurement, compare it against the greenhouse heaters you want and see how the BTUs match up. You might need 2 or 3 greenhouse heaters to match the BTUs needed to heat your greenhouse to the perfect temperature.

First: Input the surface area in sq ft of your greenhouse.

Second: Input the coldest outside temperature while your heater will heating your greenhouse – A rough estimate will be enough

Third: Input the temperature you’ll consistently like to keep inside the greenhouse.

Forth: Using the heat loss table below the calculator, input the heat loss value that’s applicable to your greenhouse.

Fifth: Check the right side of the calculator to see how many BDUs your greenhouse needs.

Greenhouse Heater BTU Calculator

Heat Loss Calculations

4 mil polyethylene1.204 mm (5/32″) twinwall polycarbonate.70
6 mil polyethylene1.156 mm (1/4″) twinwall polycarbonate.62
6 mil poly double layer (inflated).706mm polycarbonate roof & glass walls.90
11 mil woven polyethylen1.058 mm (5/16″) twinwall polycarbonate.58
3 mm (1/8″) glass (single layer)1.1310mm (3/8″) twinwall polycarbonate.53
Double layer insulated glass.4510 mm (3/8″) triple wall polycarbonate.48
Polycarbonate / fiberglass (single layer)1.2016 mm (5/8″) 5 wall polycarbonate.33

If the greenhouse needs 10,000 BTUs to keep it at 70 degrees.
And the greenhouse heater outputs 5,000 BTU per hour
You will need 2 x 5,000 BTU heaters to keep your greenhouse at its desired temperature.

Buying the Best Heater for Greenhouse

To maintain a specific temperature in your greenhouse for the plants, you will inevitably need a heater that fixes the temperature to the one you want. The plants in your greenhouse may not survive in other temperatures, so you want the heater to function efficiently, without supervision too.

The new range of heaters for the greenhouse is designed to solve your problems. They also come in an affordable range for price and have a minimum effect on the electricity bill. You need a portable greenhouse heater to not only maintain a specific temperature for the plants but also for you to work in your greenhouse.

The chilling cold temperature in the greenhouse may inhibit you from working there. This is when an efficient greenhouse heater comes in handy, as they are easy to assemble, safe to use and keep a warm temperature across the greenhouse.

Moreover, you no longer need to worry about electricity bills while purchasing these energy-efficient heaters as they will incur a minimum cost of operation and maintenance. These new heaters are durable and have long cords for use in many places. They are also not costly and have minimal maintenance needs. 

BEST overall
  • BTU/h 5,118
  • 1500 W
  • Heating for L or M space
  • Electric
  • Cable length 48 Inches
  • Thermostat included
  • BTU/h 50,000
  • Gas
  • Heating for XL or L space
  • Gas & Electric
  • Thermostat included
  • BTU/h 5,118/2559
  • 1500/750 W
  • Heating for M or S space
  • Electric
  • 96 Inches
  • Thermostat included
iPower Electric Heater Fan
  • BTU/h 5,118
  • 1500
  • Heating for L or M space
  • Electric
  • 75 Inches
  • Thermostat included
Buyplus Electric Greenhouse Heater
  • BTU/h 5,118/2559
  • 1500/750 W
  • Heating for M or S space
  • Electric
  • 89 Inches
  • Thermostat included

Bio Green PAL 2.0/USDT Palma Greenhouse Heater With Digital Thermostat

The Plama greenhouse heater from Bio-Green can be used in various arrangements, such as a milk-house, garage, greenhouse heating, and sheds. It has an external sensor that measures the temperature inside the greenhouse. It comes with a stainless-steel housing and an x4 splash-proof display. It is a low-maintenance heater that can be conveniently operated without any high costs. It is most valued for its temperature control and accuracy. It has a digital thermostat, stainless steel casing, and a compact size. The company has a more excellent customer service that is very responsive to the concerns of the clients. 

You can leave this heater unsupervised, and rest assured that it will maintain the temperature without having you check it with a thermostat regularly. The most important thing about this heater is that it does not incur any extra bill, so you can safely use it without worrying about any extra budget burden. 

The waterproof spray design and stainless-steel construction impart extra durability to this heater. It can efficiently heat an area to 120-square feet. It has a small size, so it is portable, having a power output of 1500 Watts, 5118 BTU. The digital thermostat could be set to a wide range of temperatures, from -58 to 210 degrees on the Fahrenheit scale. 

You can use the ventilation/heating dial to prevent the formation of mold and circulate air. It has a splash-proof design to guard against any humid conditions. It is effortless to clean and maintain; moreover, high air circulation prevents mold formation on plants. This heater is energy-efficient, safe, compact, and powerful. 

It can also be used in any damper area, such as the outbuildings, storage rooms, and workshops. Moreover, it may also be used as an emergency heater. It offers a rugged construction with a steel casing. It functions perfectly in greenhouses up to the size of 120 sq feet. It has a heating power of 1.5kW and circulates this heat at a rapid rate of 163 cubic meters per hour. You can easily circulate heat at this rate in your greenhouse with a convenient and easy-to-use dial that comes with it. 

You can also use Palma to fix the greenhouse temperature below 32 degrees Fahrenheit by using the Palma digital version of the thermostat. In this way, it is well adapted to promote the cultivation of those pants that sprout in the frost. 

Palma is a brand known for creating heaters that function efficiently for small area greenhouses. For making the greenhouse stay free from frost, its temperature must ideally stay below 32 degrees Fahrenheit, even in the region of corners.

If the air currents do not reach those regions, then the heater’s temperature must be kept much high; still, a large proportion of that heat also goes into the gable of the greenhouse, where it is not required, leaving the corners still in the minus temperatures. This process wastes the energy of heating. The heaters manufactured by Bio Green avoid these situations by ensuring that the switching stays differential to a minimum. 

Accurate thermostat
Functions without supervision
Compact build
Energy efficient
Some report issues with thermostat

What real owners say:

“This heater is perfect for a small 6×8 greenhouse”

“This greenhouse heater is very efficient. It warms our greenhouse of 12′ x 20′ up to 15 degrees more than the temperature outside.”

Mr. Heater Big Maxx – Natural Gas Heater

I have used this heater and I can tell you it’s a beast! The heat output is really impressive. It will easily heat a larger greenhouse and keep it nice and warm at a constant temperature through the winter months.

The Big Maxx from Mr. Heater is a gas heater with a massive 50,000 BTU output per hour. This is the highest BTU output per hour on my list of greenhouse heaters so if you have a large greenhouse then you want to consider this one.

There are a couple of options when choosing this greenhouse heater, either the heater with a thermostat or the heater with a 5-piece universal gas appliance connection kit. Both the thermostat and gas connection is from Mr. Heater and can be found separately here:

Mr. Heater Thermostat (Amazon link)
Mr. Heater Gas appliance hook-up kit (Amazon link)

Ventilation is required when using this heater – the Mr. Heater Horizontal Vent Kit (Amazon link) is designed to work with this heater, although a little expensive, it is compatible.

With a supply of liquid propane, you can have this heater up and running keeping your greenhouse nice and toasty for growing all your greenhouse greens.

This is a massive 50,000 BTU per house and has the ability to heat a 1,250 sq ft space quickly, quietly and safely. Mr. Heater themselves actually say that it is ideal for 1,667 sq ft which is considerably bigger than what others have stated.

The unit comes with a couple of mounting brackets which are great for a garage ceiling but If you intend to use this in a greenhouse with plastic or polycarbonate walls then I would recommend mounting this on built support making sure the heater doesn’t touch the walls and make sure that condensation doesn’t drip on it either.

Although this heater uses natural gas or liquid propane to heat, it is still required to be connected to 115v AC mains. The electrical connection is to power the auto spark ignition and the built-in electric high-velocity fan which pulls cool air into the rear of this heater.

The thermostat is easily mounted and will do a great job at regulating and keeping a consistent temperature in your greenhouse.

It really is a very well build, strong, durable and long-lasting heater that is perfect for larger spaces and if you are looking for the best greenhouse heater for a larger space, then this is it!

Efficient air circulation fans
Stainless steel casing
Energy efficient
Less accurate temperature control
Heat output

What real owners say:

“This is our long sought-after solution for our greenhouse”

“Using it in my small greenhouse, but this can easily be used in larger greenhouse”

AgiiMan Patio Space Heater Portable

The AgiiMan patio space heater is ideal for a greenhouse because of its portability, compact size, and heating ability.

It is designed to warm small areas. It comes with an adjustable thermostat and an advanced ceramic heating element that is more efficient and faster than conventional fan heaters. 

It is a ceramic heater, so it is quick to heat; it produces bulk heat without opening coils and has a durable construct.

It has only 8 feet long cord and comes with the facility of PTC overheat protection and 3s quick heat. 

You can adjust the temperatures between 750 watts to 1500 watts. The fan in the heater blows out cool air. To adjust the temperature, you must turn the thermostat knob toward the + sign. This heater is energy efficient and has a minimum impact on the electricity bills. It is safe to use and easy to maintain. The built-in automatic overheats system inside shuts it off when its parts start to overheat. So, you can conveniently use it in a house having pets and children.

 The customer valued this heater more than the Bio green PAL 2.0/USDT Plasma Greenhouse Heater for that it is easy to assemble, maneuverable, safe to use, and for its output of heat. It seamlessly fits in the area, and you also do not need to worry about blowing any circuit breakers. Even on turning off this heater, you can use the fans in the unit to circulate the air in the area. 

It has an extra-long cord and heats up the area in just 3 seconds. It is also a versatile heater, so you can use it in a variety of settings, such as greenhouse, office, grow tent, and the like. 

The heater can be used readily as its parts are seamlessly assembled. It has ceramic heating elements that impart sturdiness to the structure. 

It is quick at warming the atmosphere and takes just a few seconds to do so. It comes with a 90 degrees tilt rotation and a range for heating. This heater must not be put on the wet ground to keep its metal safe from rusting for an extended duration. 

Compact size
Safe to use
Not ideal for larger greenhouses

What real owners say:

“It gets hot very quickly, the built-in fan distributes heat well”

“This heater has the best heat output that I’ve experienced with a space heater”

iPower Electric Heater Fan (B08MW5CSNY

The iPower electric heater comes with a digital cooling thermostat controller particularly designed for greenhouses, overheat protection, spray waterproof, and fast heating mechanisms. It is fast enough to heat up in three seconds. 

It is a portable and versatile heater that you can use in a variety of places, in addition to the greenhouse, such as, workplace, grow tent. It consists of an independent heating device and a cooling device.

 It comes with a mechanism to ensure safety. In the situation of an overload, the screen display and power output cut off, so it is overload protected and safe to use. The overheat protection mechanism is enabled by a heat limiting thermostat installed inside it and an overheat protection circuit. When it reaches a particular temperature that can potentially damage the system by overheating, the system shuts off the heater automatically. In that case, you should unplug the heater and make it cool for ten minutes before restarting the system again. 

This heater’s waterproof spray feature makes it ideal for greenhouses, grow tents, and barn. It has an exact thermostat controller, a waterproof probe for sensing temperature ranging from -58 degrees to 230 degrees Fahrenheit. The controller has working temperatures from -40 degrees Fahrenheit to 176 degrees Fahrenheit. The digital display shows temperature in both the Celsius and Fahrenheit units.

 It is useful for application to areas up to 160 square feet. Users have been most satisfied with its safety features. The shortcoming of this heater is also its heat output. 

When it comes to the accuracy of temperature control, buyers have been most satisfied with the Bio Green PAL 2.0/USDT Palma. 

The metal case of this heater makes it a better choice than the plastic case heaters, as it makes this heater more durable. 

It also meets the new condition set for greenhouse heaters, that they must have an IPX4 rating or higher. This means that they must stay strong against any splashing or wet conditions. 

Accurate thermostat
Fast heating
Fragile fan

What real owners say:

“Good value for the money.”

“perfect heater for a small place”

Buyplus Electric Garage / Greenhouse Heater

The Electric garage/greenhouse heater from Buyplus is a portable heater with an adjustable thermostat, useful for heating small areas, such as a garage, grow tent, workplace, office, or a small greenhouse. This heater also comes with overheat protection mechanisms and a metal base.

The PTC technology makes it cool down more quickly as the PTC stones do not give off any heat. So, this heater is efficient at avoiding any overheating situation. The PTC technology makes it certain that the internal temperature of the heater does not stay high for long. So, this heater is safer and more durable than other heaters. 

It has a long cord, so you can also use it in the workplace or garage. It is quick to heat and functions without making any noise. This heater warms the atmosphere instantly. It has three settings for heat, low heat, high heat, and fan only. 

This heater is fast at warming the environment with its 1500 watts engine and takes just three seconds in doing so. It easily adjusts in the heating system of the house, and you do not require to crank up the thermostat functioning for the complete house when you are only in one room. It can give off 1500 watts of heat when in a high setting. 

The Fan Only option allows it to circulate refreshing air with no addition of heat. No need to worry about any bills for electricity. 

This heater is safe to use in that it has an auto shut-off mechanism. Even if you forget to turn off this garage heater during the night, it shuts off when it reaches the set temperature to protect itself from overheating. The new PTC technology ensures rapid heating without any flame or red light incurred during the process. 

PTC Technology
Long cord
Fast Warming
Might struggle on the really cold days to heat a larger greenhouse

What real owners say:

“Simple and easy to operate, fast heating speed. The appearance is novel, the plug power cord is long and convenient to move”

“Good heater”

Buyer’s Guide

To get an ideal heater for your greenhouse, you should look for the following features in your heater:


You do not want your heater to misfunction in less than a year. Several heaters do not last for long. You may purchase them for their other excellent features, but it does not take you long to be dismayed with your purchase as the heater stops functioning. So, not just look for the best features in a heater, but also seek durability to get a product that serves you in the long run. The thermostat or other parts of a heater may also stop functioning in fragile heaters. 

Utility Bill

The most frequent apprehensions about purchasing an electrical heating system are about the associated bills. It is still widely believed that anything powered by electricity is expensive. You do not want to spend hefty amounts on electricity bills by using an electric heater. So, choose a heater that costs low in terms of electricity bills.

Compact size

You should get a portable heater that you can adjust conveniently anywhere you want.


This is an essential aspect that you must not overlook. Ideally, your heater must operate safely. It means that it must not pose any harm to those in the environment or itself. The heater can burn out if its temperature gets beyond a specific limit. 

Time for Warming

You should choose a heater that takes minimum time for warming the environment by fixing it at a new temperature. 

Range of temperature

You should know the temperature you want to maintain in your greenhouse and get a heater accordingly.


Always check the warranty given by the manufacturer as manufacturing faults are also common in several appliances and commodities. 

Construction Material

Material of construction imparts several features to the product, such as durability. Stainless steel heaters are a popular choice presently that they are durable. 

Ease of Cleaning

The heater should be easy to clean. You do not want a heater that will make you worry about damaging the product while cleaning. As it is an electric heater, so your foremost concern is not to damage it while cleaning or wiping it.


You want your heater to function smoothly without any interference or supervision needs. Moreover, you want it to be sturdy without having any associated costs for maintenance.

Even Warming of Area

You do not want any cold pockets in your greenhouse, and for that, the heater must be good at air circulation so that it warms the area evenly. 

Accurate Thermostat

The thermostat must accurately fix the temperature to the set value. 

Energy Efficiency

For avoiding high electricity bills, the heater should be energy efficient; that is, it must convert most of the input power to output, with minimum power losses in the system. 

FAQ: Best heater for greenhouses

Below are some of the more common questions people usually asked about greenhouse heaters. I thought I would try and clear the uncertainty a little by answering a few of those common quesitons.

Can these heaters be only used in a greenhouse?

No, you can use them in several small areas, such as a garage and an office too, in addition to a greenhouse. They come with a variety of temperature ranges, so you can choose a temperature that best suits the plants and vegetables in the greenhouse or enables you to work in the place seamlessly.

Will these heaters increase my electricity bill too much?

No, the new heaters and cost-effective and energy-efficient. They utilize the maximum of the input energy so that minimal energy is lost in the system. 

Are these heaters safe for use?

Yes, they have built-in mechanisms which protect them from burning out. In case if you forget to turn the heater off, then they have a mechanism that shuts them off before any of their parts or equipment may burn out. 

Will my greenhouse warm uniformly with this heater?

Yes, these heaters circulate the air efficiently, making the temperature even across your greenhouse. The fan inside the heater circulates the air so that the temperature stays constant in the area.

Will the heater easily fit into the electrical system of the house?

Yes, they are easy to install and assemble. You do not need any special arrangements to install them. 

Can I place the heater on the ground?

Yes, they have special structures with which you can easily mount them on the ground.

How much will be the maintenance cost for them?

These new heaters are an efficient replacement for the previous plastic heaters, as the stainless-steel casing and ceramic structures make them sturdier. One of their specialties is low maintenance requirements.

Is it difficult to clean these heaters?

No, you can clean them easily by wiping. Then you do not need to worry about damaging them while cleaning as they have waterproof, resilient structures that especially adapt them for outdoor use.

All In All

All in all, this is what each product is best at:

  • Bio Green PAL Greenhouse Heater 2.0/USDT:– accurate thermostat, durable, portable, and compact build. No extra budget burden and extra durability.
  • Mr. Heater Big Maxx: Quiet, safe, durable, and ideal for large greenhouses.
  • AgiiMan Patio Space Heater: compact size, easy to assemble, and safe to use. Extra-long cord and heats up the area in seconds..
  • iPower Electric Heater Fan: versatile, fast heating with accurate thermostat. Overheat protection and fast heating mechanism.
  • Buyplus Electric Garage Heater: – Greenhouse Heater – PTC technology with long cord and safety mechanisms. Fast warning and portable.

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