5 Best Heaters For Greenhouses

  • By: Rob Jones
  • Date: May 27, 2022
  • Time to read: 14 min.
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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. 

Buying the Best Heater for Greenhouse

Need to know how many BTUs your greenhouse needs? check with our BTU calculator below the reviews or click HERE

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 for s-m sized greenhouse
Bio Green PAL 2.0/USDT
  • BTU/h 5,118
  • 1500 W
  • Heating for S or M space
  • Electric
  • Cable length 48 Inches
  • Thermostat included
Mr. Heater Big Maxx
  • BTU/h 50,000
  • Propane
  • Heating for XL or L space
  • Gas & Electric
  • Thermostat included
BEST FOR m-l sized greenhouse
Comfort Zone Ceiling Mount Heater
  • BTU/h 5,118/2559
  • 5000 W
  • Heating for M or L space
  • Electric
  • Dial thermostat
Mr. Heater Portable Propane Heater
  • BTU/h 60,000
  • Heating for L or M space
  • Propane
  • No Thermostat
BEST for s-m sized greenhouse
AgiiMan Space Heater Portable
  • BTU/h 5,118
  • 1500 W
  • Heating for S or M space
  • Electric
  • Cable length 8 feet
  • Dial thermostat

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

The Bio Green PAL 2.0/USDT Palma Greenhouse Heater is a compact, energy-efficient, and safe heater that is ideal for heating a small to a medium-sized greenhouse.  

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.

Key Information:

  • Will heat a small to medium-sized greenhouse
  • Electric heater
  • With digital thermostat
  • 5118 BTU output

You can easily circulate heat at this rate in your greenhouse with a convenient and easy-to-use dial that comes with it. 

The heater has a digital summer/winter thermostat and an external sensor cable to measure the ambient temperature in the greenhouse.

The heater features stainless steel housing and heat elements that are engineered in Germany for greenhouse heating use.

The 5118 BTU/1500 W heating output of the fan ensures that the space will be heated quickly and efficiently. The heater is also very inexpensive to operate, which is great for long hours of heating.

This heater offers important advantages such as a high ventilation rate of up to 460 m³/h. The ability to use the fan setting to cool down the greenhouse in the summer. Allowing for air circulation in the summer, which is necessary for the pollination of many flowers and vegetables.

The Bio Green PAL 2.0/USDT Palma Greenhouse Heater is a great choice for anyone looking for an energy-efficient and safe greenhouse heater.

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

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.

Key Information:

  • Will heat a large to very large greenhouse
  • Propane heater
  • With digital thermostat
  • 50, 000 BTU output

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

Comfort Zone 5000W Fan-Forced Ceiling Mount Heater with Dual Knob Controls

The Comfort Zone 5000W Fan-Forced Ceiling Mount Heater is a durable and efficient commercial heater that is designed for ceiling mounting.

It features a heavy gauge steel body, which makes it tough and able to withstand temperature fluctuations.

Key Information:

  • Will heat a medium to large-sized greenhouse
  • Electric heater
  • With a dial thermostat
  • H:17,065 BTU M:14,105 BTU S:11,285 BTU

The heater also has a built-in sensor that switches it off automatically if it overheats. Additionally, it has a power indicator light to let you know when it is turned on. The fan-forced design helps to distribute heat throughout the room, while the adjustable louvers direct output where it is needed most.

The thermostat control allows you to easily adjust the temperature to just the right level. The heater is also easy to operate, with dual knob controls that let you turn it on and off quickly.

The Comfort Zone 5000W Fan-Forced Ceiling Mount Heater is a space-saving design that is perfect for medium to large greenhouses. It has 3 heat levels, the highest at 5000 watts, which distributes 17,065 BTUs, perfect for a very large greenhouse.

It also has a 4000 watt and 3000-watt heat setting which would heat a medium to the large-sized greenhouse. The 4000 what distributes 14,105 BTUs and the 3000 watts is 11,285 BTUs

Accurate thermostat
Safety sensor 
Fast heating
Can get expensive

Mr. Heater Portable Propane Heater

The Mr. Heater Portable Propane Forced Air Heater is a 20-pound propane heater that is perfect for heating your large to the very large greenhouse without any problems.

It is powered by propane and a 12v lead acid battery, and it has a maximum runtime of 14 hours.

Key Information:

  • Will heat a large to very large-sized greenhouse
  • Propane heater
  • No thermostat
  • 30,000 to 60,000 BTUs

The heater has a variable output of 30,000 to 60,000 BTUs, and it can heat up to 1,250 square feet quickly and toasty.

The Mr. Heater Portable Propane Heater is equipped with Mr. Heater’s patented Quiet Burner Technology, which makes the heater 50% quieter than a standard propane heater.

The heater is also rugged and durable, with steel construction that is built to last. It is also economical, efficient, and clean-burning. This portable heater comes with a 10-foot hose and regulator, and it is CSA certified.

There is the MH60QFAV model – but there are 6 models in total which range from 38,000 BTU all the way up to a massive 400,000 BTU.

High BTU
Quiet burner technology
No thermostat
Consumes oxygen fast

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.

Key Information:

  • Will heat a small to medium-sized greenhouse
  • Electric heater
  • With dial thermostat
  • 5118 BTU output

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

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

Two columns
Input Values
How Many BTUs Are Needed For Your Greenhouse
Name Total
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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.

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.
  • Comfort Zone Heater: Ceiling mounted fan that is perfect for large spaces.
  • Mr. Heater Portable Propane Heater: – Great for heating large to very 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.

Rob Jones

Rob is an enthusiast of all backyard DIY projects. He has spent many years researching, learning, and building. From a backyard shed to a garden pond, Rob will have done it!

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